Glossary

A collection of biologically terms.

Abaxial	Abaxial means being located on the side away from the axis. The abaxial surface of a leaf is its underside.
Abscisic Acid	Abscisic acid is a plant hormone that inhibits growth, causes the abscission of leaves, induces dormancy, closes stomata, and triggers other phenomena in response to adverse conditions.
Abscission	Abscission is the normal separation of a leaf, fruit, or flower from a plant. Abscisic acid is the plant hormone involved in abscission.
Abscission Zone	The abscission zone is the area at the base of leaf's petiole, a fruit stalk, or a branch in which the separation (abscission) layer develops. The disintegration of this layer causes a leaf, fruit, or flower to fall from a plant. Abscisic acid is the plant hormone involved in this process.
Acicular	Acicular means needle-like (for example, pine needles are acicular).
Acid rain	Acid rain is polluted and harmful to the environment. Acid rain has a low pH. Acid rain may have been a component of the K-T extinction.
Achene	An achene is a dry, indehiscent one-seeded fruit with a leathery pericarp that is easily separated from the seed coat (for example, sunflower).
Adaxial	Adaxial means being located on the side towards the axis. The adaxial surface of a leaf is the upper side.
Adenosine Triphosphate	ATP (short for adenosine triphosphate) is a nucleotide that has a ribose sugar and three phosphate groups. ATP is a high-energy molecule used for energy storage by organisms. In plant cells, ATP is produced in the cristae of mitochondria and chloroplasts.
Adventitious	Adventitious organs are those organs that grow from an unusual part of the plant. For example, fibrous adventitious roots grow from the trunk above the ground instead of starting underground.
Aerial Root	An aerial root is a plant's root that is produced above the ground.
Agriculture	Agriculture is the science of farming, including growing plants and raising animals.
Agro forestry	Agro forestry is a land use system in which woody perennials are grown with agricultural crops (together with other land uses, like animal production).
Agrology	Agrology is a branch of soil science that studies the soil used in producing crops.
Agrostology	Agrostology is a branch of botany that studies grasses.
Air Plants	Air plants (also called epiphytes) are plants that live attached to a plant (or other structure like a telephone pole or a building) and not in the ground). Epiphytes include many orchids and bromeliads. Epiphytes are not parasites; they get water and nutrients from the air (and not from their host).
Algae	Algae are simple photosynthetic organisms that belong to the kingdom Protista. Most algae are aquatic; seaweeds are algae. Some algae are unicellular while others are multicellular.
Alien	An alien is a plant that is not native to a place; it came from another place.
Aloes	Aloes are succulent, clumping plants with fleshy, toothed (non-fibrous) leaves. There are about 300 species of aloe; they live in warm, dry habitats and most originated in northern Africa. Aloe Vera is a popular plant whose gel-like sap is used as a medicinal salve; it is originally from northern Africa, the Cape Verde Islands, and the Canary Islands. Aloe Vera has grey-green leaves and tubular yellow flowers that grow on a stalk that is up to 3 feet tall.
Alternate	An alternate pattern of leaves or buds is a pattern in which there is one leaf (or bud) per node, and on the opposite side of the stem (not in pairs).
Alavrez Theory of Extinction	This theory is that a large asteroid, meteor, or comet hit the Earth 65 million years ago, causing huge atmospheric and geologic disruptions, leading to a mass extinction which killed the dinosaurs and many other plant and animal species.
Amber	Amber is a yellowish, fossilized tree resin (from conifers) that sometimes contains bits of trapped matter.
Amyloplast	An organelle (with double membranes) in some plant cells that stores starch. Amyloplasts are found in starchy plants like tubers and fruits.
Angiosperm	(pronounced AN-jee-oh-sperm) Angiosperms (meaning "covered seed") are flowering plants. They produce seeds enclosed in fruit (an ovary). They are the dominant type of plant today; there are over 250,000 species. Their flowers are used in reproduction. Angiosperms evolved about 145 million years ago, during the late Jurassic period, and were eaten by dinosaurs. They became the dominant land plants about 100 million years ago (edging out conifers, a type of gymnosperm). Angiosperms are divided into the monocots (like corn) and dicots (like beans).
Annual	An annual is a plant that goes through its entire life cycle within a year. It grows from a seed, matures, produces seed, and dies within a year.
Annual Ring	Annual rings are concentric circles that appear on tree trunk cross-sections that mark the end of a growing season. These rings show whether the tree grew a lot or a little that year.
Anther	The anther is the tip of a flower's stamen. The anther contains the pollen.
Anthophyta	Anthophyta are flowering plants, the largest group of plants (which includes the grasses). The flowers are used in reproduction. They evolved during the Cretaceous period.
Apical Dominance	Apical dominance is the phenomenon in which a terminal (end) bud inhibits the development of lateral (side) buds.
Apical Meristem	The apical meristem consists of meristematic cells located at the tip (apex) of a root or shoot.
Apogeotropic roots	Apogeotropic roots are roots that grow upwards to the soil surface (other roots grow downwards), emerging from the soil and growing upwards. The sego palm has apogeotropic roots, as do cycads.
Apomixis	Apomixis is a type of reproduction in which a plant produces seeds without fertilization.
Johnny Appleseed	Johnny Appleseed was a man who spread apple trees through the USA. His real name was John Chapman, but he was called Johnny Appleseed because of his love for growing apple trees.
Aquatic	Aquatic organisms are those found in water. Many plants are aquatic, including seaweeds.
Arable	Arable land is suitable for growing crop plants.
Arboreal	Arboreal means living in trees. Many animals are arboreal, including the sugar glider.
Arboretum	An arboretum is a park or garden where trees and shrubs are grown for educational and/or scientific uses.
Arcuate	Leaves with arcuate venation have veins that are curve towards the apex (tip).
Areoles	Areoles are circular clusters of spines on a cactus. Flowers bud at an areole and new stems branch from an areole.
Arid	An arid area is dry and hot, with little rainfall and few plants.
Atmosphere	The atmosphere is the mixture of gases that surrounds the Earth. The Earth's atmosphere is mostly nitrogen.
Atom	Everything is made up of tiny atoms. An atom is the smallest part of an element that has the properties of that element.
Auxin	Auxins are growth hormones found in plants. Auxins induce phototropism, apical dominance, cell elongation and many other reactions.
Awn	The awn is a bristle-like extension of a plant near its tip.
Axil	The axil of a plant is the angle between the upper side of the stem and a leaf, branch, or petiole. In flowering plants, the bud develop in the axil of a leaf.
Axillary Bud	The axillary bud is a bud that develops in the axil (the angle between the stem and the leaf) of a plant.
Axis	The axis of a plant runs through the middle of it, e.g., the stem of a plant or the rachis of a compound leaf.
Bamboo	Bamboo is a fast-growing monocot grass.
Banana	The banana tree is an herbaceous plant (because there is no woody tissue in the stem), it is also considered a fruit (because the seeds of the plant are contained within the banana).
Bark	The bark is the outer covering of the trunk, branches, and roots of trees.
Barley	Barley is a cereal grain related to wheat, oats, and rice. Barley seeds (the part of the plant that is highest in nutrition) grow in spikes at the tips of the stems - it resembles wheat. This important crop is grown in temperate areas and is used as animal feed, for malt (used in making beer, malted milk, and food flavouring), and for human consumption (used as a flour, a thickener, a cereal, in soups, etc.). Barley was cultivated thousands of years ago; it was grown by the Egyptians from 5,000 to 7,000 years ago.
Bennettitaleans	Bennettitaleans, also called cycadeoids, are primitive plants (gymnosperms) that resemble cycads (but they are not cycads), but have different methods of reproduction. Bennettitaleans lived throughout the Mesozoic Era. Examples of bennettitaleans include Williamsonia (Jurassic through end Cretaceous), Williamsoniella (Jurassic through end Cretaceous), and Zamites (Triassic).
Berry	A berry is a small, juicy, fleshy, stoneless fruit that contains one or many seeds. This simple fruit has a pulpy pericarp surrounding the seed. Some berries include the gooseberry, tomato, currant, and grape.
Biodiversity	Biodiversity is the abundance of different plant and animal species found in an environment.
Biomass	A biomass is the total amount of living material in an area. It is calculated by adding up the weights of all of the organisms
Bladder	A bladder is a small, air filled sac. Some plants, like bladderwort (a seaweed), have air bladders.
Branch	A branch is a part of a tree or shrub that grows from the trunk or stem.
Bromeliads	Bromeliads are a group of plants that have stiff, waxy leaves that form a cup-shaped body. This "cup" catches and retains water during wet weather, and the plant uses this water to live through dry spells. Most bromeliads are xerophytes (able to tolerate a dry environment) and epiphytes (living attached to another plant and not rooted in the ground.
Bryophytes	Bryophytes (Phylum Bryophta) include the hornworts (Class Anthocerotae), liverworts (Class Hepaticae), and mosses (Class Musci). These low-growing plants do not have true roots, leaves, or stems - they also lack a vascular system (the internal tubes that transport food and water in more advanced plants). Bryophytes probably evolved from green algae; fossils of bryophytes are rare.
Bud	A bud is a small, developing part of a plant that will grow into a flower, a new leaf or a stem.
Bud Scale	A bud scale is a modified leaf (or similar structure) that covers and protects the bud.
Bulb	A bulb is an underground stem, usually globular, that has fleshy leaves emerging from the top and roots emerging from the bottom. The fleshy leaves store food. Examples include the tulip, narcissus, and onion.
Buttresses	Buttresses are tree trunk supports that help hold up tall trees in rainforests. They are needed to stabilize the tree because the soil is shallow (only a few inches deep) and the tree roots do not penetrate very deeply into the earth.
C3 Plant	A C3 plant is one that produces phosphoglyceric acid, (a molecule that has three carbon atoms) as a stable intermediary in the first step in photosynthesis (the Calvin Cycle). Most plants on Earth (over 95 percent) are C3 plants.
C4 Plant	A C4 plant is one that produces oxaloacetic acid (a molecule that has four carbon atoms) as a stable intermediary in the first step in photosynthesis. Very few plants on Earth (less than 1 percent) are C4 plants (including corn and sugarcane). Photorespiration in C4 plants is more efficient in strong light.
Cactus	A cactus (the plural is cacti) is a succulent plant that can live in dry areas. It has a structure that minimizes water loss. The stems are photosynthetic, green, and fleshy. The leaves are reduced to spines or are absent.
Calvin Cycle	The second stage in the process of photosynthesis is called the Calvin Cycle (it is also called the Calvin-Benson Cycle or the Carbon Fixation Cycle. In the Calvin Cycle, carbon molecules from carbon dioxide, CO₂, are fixed into the sugar glucose, (C₆H₁₂O₂) (in six repeats of the cycle). The Calvin Cycle takes place in the stroma of eukaryotic chloroplasts. The major enzyme that mediates the Calvin Cycle is Rubisco (ribulose-1-5-biphosphate carboxylase). The Calvin Cycle was first investigated in the late 1940s and early 1950s by the Nobel Prize winning chemist Melvin Calvin (1911-1997).
Calyx	The calyx is the sepals of a flower.
Cambium	Cambium is a layer of dividing cells found in the stems of plants. The cambium forms the specialized xylem and phloem cells and causes the stem to increase in thickness.
Canopy	The canopy consists of the upper parts of the trees of a rainforest (about 65 to 130 feet or 20 to 40 m above the ground). The canopy is the part of a forest in which the branches of the trees spread out and block sunlight from reaching the forest floor. This leafy environment is full of life in a tropical rainforest and includes insects, birds, reptiles, mammals, and more.
Capillary Action	Capillary action is the movement of water as it is pulled upwards through tubes (xylem) within a plant's roots, stems, and leaves. The water (containing minerals and dissolved nutrients) is driven against gravity by adhesion of the water molecules (they stick to the sides of the tubes), cohesion of those molecules (the water molecules sticking together), and surface tension (the forces of the molecules on surface of the upward-moving water).
Capsule	A capsule is a seed pod that opens when it is dry and the seeds are mature.
Carbon Dioxide	Carbon dioxide, CO₂, is a molecule that has one carbon atom and two oxygen atoms; it is a gas at standard temperature and pressure. Plants use carbon dioxide gas in the photosynthetic process.
Carpel	The carpel is the female reproductive organ of a flower - it makes the seeds. It consists of the stigma, style and ovary. There may be more than one carpel in a flower.
Casparian Strip	The Casparian strip is waxy layer (a band of suberin, a waterproofing material) that is located in the walls of plant root cells. This barrier strip stops the transport of water and minerals into the main vascular system of the root.
Caudex	The caudex is an enlarged, woody base of the stem or trunk (located just below the ground) on some plants - it is used for water storage. Many desert plants have a caudex, an adaptation to dry conditions. Some palms, cycads, and succulents have a caudex.
Cell	The cell is the basic structural unit of all organisms. Plant cells have a tough outer cell wall, a cell membrane, genetic material (DNA), cytoplasm, and many organelles.
Cell Membrane	A cell membrane (also called the plasma membrane or plasmalemma) surrounds each plant cell (it is located within the cell wall).
Cell Wall	Plant cells have a thick, rigid cell wall located outside the cell membrane. The cell wall is made of cellulose (a polysaccharide carbohydrate), proteins, and sometimes lignin. The cell wall gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant.
Cellular Respiration	Cellular respiration is a process in which energy is produced from various molecules (like glucose), producing ATP (adenosine triphosphate). During cellular respiration, oxygen is used and carbon dioxide is produced Cellular respiration occurs in the mitochondria of eukaryotes, and in the cytoplasm of prokaryotes.
Cellulose	Cellulose is a carbohydrate that comprises much of a plant's cell, especially the cell wall.
Centrosome	A centrosome (also called the "microtubule organizing centre") is a small body located near the nucleus - it has a dense centre and radiating tubules. The centrosome is where microtubules are made. During cell division (mitosis), the centrosome divides and the two parts move to opposite sides of the dividing cell.
Cereal	A cereal is a grain that is used for human food. Some cereals include rice, oats, wheat, and barley.
Chlorophyll	Chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into sugar and oxygen (this process is called photosynthesis). Chlorophyll is magnesium based and is usually green.
Chloroplasts	Chloroplasts are small green structures in plants that contain chlorophyll. Leaves have many chloroplasts.
Cladode	A cladode is a stem that looks like a leaf.
Clade	A clade is a group of all the organisms that share a particular common ancestor (and therefore have similar features). The members of a clade are related to each other. A clade is monophyletic.
Cladistics	Cladistics is a method of classifying organisms based on common ancestry and the branching of the evolutionary family tree. Organisms that share common ancestors (and therefore have similar features) are grouped into taxonomic groups called clades. Cladistics can also be used to predict properties of yet-to-be discovered organisms.
Cleft	A cleft (also called parted) leaf is one in which the margins between the irregular teeth go more than halfway to the midrib.
Cloud Forest	A cloud forest is a rainforest that is on a mountainside. It is usually misty and cloudy.
Climax Vegetation	Climax vegetation is the final stage in the development of an area.
Club Mosses	Club mosses (Lycopsids) are primitive, vascular plants (pteridophytes) that evolved over 375 million years ago (during the Devonian). Huge club mosses went extinct during the Permian mass extinction; smaller ones lived during the time of the dinosaurs. These plants live near moisture (in order for their spores to germinate). These fast-growing, resilient plants propagate with rhizomes (underground stems).
Coleoptile	A coleoptile is a protective sheath that surrounds the shoot tip and the embryonic leaves of the young shoot of grasses.
Complete Flower	A complete flower has a stamen, a pistil, petals, and sepals.
Composite Flower	A composite flower (like the sunflower) has a many individual flowers (called florets) on wide, flat receptacles that look like a single flower. The flowers in the central disk are called disk flowers; the flowers on the periphery are called ray flowers. This group is called Asteraceae (Composite).
Compound Leaf	A compound leaf is a leaf that is divided into many separate parts (leaflets) along a midrib (the rachis). All the leaflets of a compound leaf are oriented in the same plane. When a compound leaf falls from the tree, it falls as a unit. A double compound leaf is one in which each leaflet of a compound leaf is also made up of secondary leaflets.
Cone	A cone (strobilus) is the reproductive fruiting structure of many tracheophytes. It is a group of scales that are joined to a central stalk; the seeds are borne on the surface of the cone scales. A cone scale contains either ovules or spores (depending on whether it is female or male).
Conifers	Most conifers are evergreen trees and shrubs that bear naked seeds in cones (a woody strobilus). Examples of modern-day conifers include pine, fir, larch, and spruce trees. Mesozoic Era conifers included redwoods, yews, pines, the monkey puzzle tree (Araucaria), cypress, and Pseudofrenelopsis (a Cheirolepidiacean). Towards the end of the Mesozoic, flowering plants flourished and began to overtake conifers as the dominant flora.
Conservation	Conservation is the wise use of natural resources (plants, animals, minerals, water, etc.) so that they are not damaged and will be in good condition in the future.
Consumer	A consumer is a living thing that eats other living things to survive. It cannot make its own food (unlike most plants, which are producers). Primary consumers eat producers, secondary consumers eat primary consumers, and so on. There are always many more primary consumers than secondary consumers, etc.
Contractile Root	A contractile root is a root that contracts (gets smaller) and pulls down the crown of the plant below the surface of the soil.
Cooksonia	Cooksonia is the oldest-known land plant. This primitive plant dates from Silurian period, about 428 million years ago Cooksonia was an erect plant with dichotomous branches and terminal sporangia (sacs that produce reproductive spores). Cooksonia fosils have been found in the USA, Canada, and Czechoslovakia.
Coppice Shoot	A coppice shoot (also called an epicormic shoot, sap shoot, water shoot, or water sprout) is a shoot (new growth) that arises from an adventitious or dormant bud on a branch or a stem of a plant (usually near the base of the plant). This fast-growing shoot often starts to grow when part of a forest canopy is removed or thinned (allowing light in).
Corpse Flower	The "corpse flower" is the world's largest flower. This giant bloom is found in rainforests of Indonesia. Its scientific name is Rafflesia arnoldi. Rafflesia gives off a putrid smell that reminds people of rotting meat (this odour attracts its pollenators, beetles and flies), hence its nickname. Rafflesia's enormous flower is about 3 feet (1 m) across and weighs about 20 pounds (9 kilograms). The flower takes about a year to develop, then it blooms for about a week before dying. The flower has five wide orange petals (with pale dots) surrounding a spiked cup. Rafflesia has no stem, no roots, and no leaves. The flower is supported by fungus-like tissue that lives in another plant - the Tetrastigma vine.
Cordate Leaf	A cordate leaf has a heart shape, with the wide part towards the petiole.
Cork	Cork (also called periderm) is the soft, light-weight bark of the cork oak tree. This low-density material floats in water. Cork cells are made by cork cambium cells. Cork contains suberin, a waxy, water-proof material. Cork protects the tree from water loss and from insects and infections.
Corm	A corm is a fleshy underground stem of some plants. It looks like a bulb, but is solid (it is not formed in layers).
Corn	Corn (Zea mays), also called maize, is a type of cereal grass; it is an edible grain. This tall, annual plant has long, alternately-spaced blade-like leaves, and a strong, solid stem. A flowering plant, staminate (male) flowers grow on the tassels at the end of the main axis of the stem. The pistillate (female) inflorescence grows into the ear of corn, and is a spike having a thick axis paired spikelets in rows (each row of paired spikelets produces two rows of grain). The ear is covered by modified leaves, called husks or shucks. Corn evolved in the Americas, but has been brought all around the world by people; it is the second-largest food crop (behind wheat).
Corolla	The corolla consists of the petals of a flower.
Cotyledon	The cotyledon is the embryonic leaf within a seed. When a seed germinates, the cotyledon is the first leaf to grow. Monocots have one cotyledon; dicots have two cotyledons.
Crenate	A crenate leaf has edges (margins) shaped like rounded teeth.
Cristae	(singular crista) The multiply-folded inner membrane of a cell's mitochondrion that are finger-like projections. The walls of the cristae are the site of the cell's energy production (it is where ATP is generated).
Cross-Pollination	Cross-pollination is the transfer of pollen from the anther to the stigma of a flower on a different plant.
Cytoplasm	Cytoplasm is the jelly-like material outside the cell nucleus in which the organelles are located (the entire contents of the cell located inside the plasma membrane, but excluding the nucleus).
Crisped	Crisped leaves have a tightly curled margin. Parsley and kale leaves are crisped.
Crown	The crown of a plant is the area from which new shoots arise or the point at which the roots meet the stem. Also, the upper area of the tree that has a lot of branching and leaves.
Cryptogams	Cryptogams are plants and plant-like organisms that do not reproduce with seeds and do not produce flowers. Many cryptogams reproduce using spores. Ferns, mosses, fungi, and algae are cryptogams.
Culm	A culm is the elongated straw or hollow stem of grasses. The culm usually supports the inflorescence.
Cultivar	A cultivar is a plant that is a cultivated (bred) variety.
Cuticle	The cuticle is the fatty or waxy outer layer of epidermal cells that are above ground.
Cycad	Cycads (Cycadophyta) are primitive seed plants that dominated the Jurassic period (cycads comprised 20% of the world flora). Cycads are palm-like trees that live in warm climates. Separate male and female plants exist (they are dioecious). These gymnosperms have long, divided leaves and produce large cones. Cycads evolved during the Pennsylvanian, had their heyday during the Mesozoic, and only about 185 species (in 11 genera) still exist today. Leptocycas and Ptilophyllum were Mesozoic Era cycads. Later cycads had a more rounded, barrel-like base.
Cyme	A cyme is an inflorescence where the central flower opens first.
Cytoplasm	Cytoplasm is a clear, jelly-like fluid found inside cells.
Cytoskeleton	The cytoskeleton is a network of protein filaments and microtubules that are located in the cytoplasm of eukaryotic cell, just under the cell membrane. The cytoskeleton acts as a support for the cell, as a spatial organizer, and as a channel for some chemical transport.
Deciduous	Deciduous plants lose their leaves seasonally, usually for the dry season. Some deciduous plants include ash, beech, hickory, maple, and oak.
Decomposer	Decomposers are organisms like fungi and some bacteria that break down and digest the remains of organisms.
Decomposition	Decomposition is the decay or breakdown of things into more basic elements. For example, after a plant dies, it decomposes into organic nutrients.
Deforestation	Deforestation is the loss of forest. Deforestation has many causes, including man's cutting down trees, forest fires, severe drought, changes in sea level, disease, etc.
Dehiscent	A dehiscent is a structure on some plants that opens to release seeds or pollen grains.
Dehiscent Fruit	A dehiscent fruit splits open when it is maturate, causing the dispersal of its seeds. Some dehiscent fruits include cotton, poppy, peanuts, milkweed, magnolia, and all beans.
Dehydrate	To dehydrate is to lose a lot of water. Plants can become dehydrated in dry, hot weather
Dendrochronology	Dendrochronology is the science in which tree rings are studied to determine conditions in the past.
Desert	A desert is a very dry area that receives less than 10 inches (25 cm) of rainfall each year. Desert organisms have adapted to life with little water.
Diaspore	A diaspore (also called a disseminule) is a part of a plant that is separated from the plant and dispersed (sent or taken away from the plant) for reproduction. Diaspora includes seeds, fruits, and spores.
Dichotomous Key	A dichotomous key is a method for determining the identity of something (like a butterfly, a plant, or a rock) by going through a series of choices that lead the user to the correct name of the item. At each step of the process, the user is given two choices; each alternative leads to other questions until the identification is completed. For example, a question in a dichotomous key for trees might be something like, "Does it have flat or needle-like leaves?" Dichotomous means "divided in two parts".
Dichotomous Venation	Dichotomous venation is a pattern of leaf veins in which the veins branch in two over and over again. Ferns are dichotomously veined. A few angiosperms and gymnosperms (like gingkos) have dichotomous venation.
Dicot	A dicot (Class Magnoliopsida) is a type of flowering plant (an angiosperm) whose seed has two embryonic leaves (cotyledons). The leaf veins are usually net-like (and not parallel). Taproots are often present. Beans and peas are examples of dicots.
Dictyostele	A dictyostele is a siphonostele (a cylinder of vascular tissue) that has two or more overlapping leaf gaps (as in ferns). It is a divided stele located in the outer cortex (instead of in the centre of the stem). Dictyosteles are composed of individual vascular bundles.
Dioecious	A dioecious plant has the male and female flowers on different plants. For example, date trees are dioecious. (Compare with monoecious.)
Dirt	Dirt is another name for soil. Soil is a natural, constantly-changing substance that is made up of minerals, organic materials, and living organisms. Plants grow in soil.
Dispersal	Dispersal is the process in which an organism spreads out geographically. Seeds are dispersed by the winds and by animals.
Dispersers	Dispersers are animals that spread plant seeds. Some dispersers include birds, insects, bats, and furry animals like monkeys.
Dissemules	A disseminule (also called a diaspore) is a part of a plant that is separated from the plant and dispersed (sent or taken away from the plant) for reproduction. Dissemules include seeds, fruits, and spores.
Dominant	The dominant plant is the most abundant species in an area, for example, pine trees are dominant in a pine forest.
Dormancy	Dormancy is a period in which a plant has no active growth in response to harsh environmental conditions (like droughts or cold seasons).
Drip Tip	The drip tip is the long, sharply-pointed tip on some rainforest plant leaves that allows water to flow quickly off the leaf surface. In the rainforest, many leaves have a drip tip. Without it, water would build up on the leaf.
Ecosystem	An ecosystem is the interrelationships between all of the living things in an area.
Embryo	An embryo is a developing plant still inside the seed. The embryo has cotyledons (embryonic leaves), a root cap, a food source and a plumule (shoot), all located inside the protective seed coat.
Emergents	Emergents are giant trees in a rainforest that are much higher (up to 270 feet or 81 m) than the average canopy height. The emergents house many birds and insects in a very dry environment.
Endangered Species	An endangered species is a group of organisms that is dwindling in numbers and may go extinct soon. Many species of plants are endangered.
Endemic	Endemic plants are native to an area and are only found in that area.
Endoplasmic Reticulum	The endoplasmic reticulum (ER) is a network of membranes in plant cells (and all eukaryotic cells) that control protein synthesis and cellular organization.
Ephemerals	Ephemerals are plants that have an accelerated life cycle. These hardy plants grow and reproduce quickly - they are often dormant during extreme weather (droughts, heat spells, cold spells, etc.). Their seeds are drought resistant. These plants often live in areas with harsh climates, like deserts and very cold areas. Some ephemerals include: Desert Paintbrush, Desert Sand Verbena, Dutchman's Breeches, Mojave Aster, and Yellow Trout Lily.
Epicormic shoot	An epicormic shoot (also called a coppice shoot, sap shoot, water shoot, or water sprout) is a shoot (new growth) that arises from an adventitious or dormant bud on a branch or a stem of a plant (usually near the base of the plant). This fast-growing shoot often starts to grow when part of a forest canopy is removed or thinned (allowing light in).
Epicotyl	The epicotyl is the part of the stem that is above the first leaves.
Epidermis	The epidermis is the outer protective layer of a plant. This tissue helps prevent injury and minimizes water loss by evaporation.
Epigynous Ovary	An epigynous ovary (also called an inferior ovary) is an ovary located below the flower parts (the calyx, corolla, and androecium). The flower parts are attached to the top of the ovary.
Epiphytes	Epiphytes are plants that live attached to a plant (or other structure like a rock, telephone pole or a building) and not in the ground). Epiphytes include many orchids and bromeliads. Epiphytes are not parasites; they get water and nutrients from the air (and not their host).
Eukaryote	A eukaryote (which means "true nucleus") is an organism whose cells have internal membranes (which divide the cell into regions that have different functions) and a structurally-discrete nucleus. They also have a cytoskeleton which controls their shape. Eukaryotes include plants, animals, fungi, and protists (they do not include blue-green algae, bacteria, viruses, and other primitive micro-organisms).
Evaporation	Evaporation is the process in which a liquid is transferred into gaseous form.
Evapotranspiration	Evapotranspiration is the process in which rain water evaporates from trees and returns to the atmosphere.
Evergreen	Evergreen plants do not lose their leaves seasonally. Pines and firs are examples of evergreens. (Compare with deciduous plants.)
Evolution	Evolution is a process in which the gene pool of a population gradually (over millions of years) changes in response to environmental pressures, natural selection, and genetic mutations. All forms of life came into being by this process.
Evolve	To evolve is to develop by the process of evolution, changing in some way as an adaptation to the environment.
Extinct	An animal species that is extinct has died out. Most animal species that ever existed have gone extinct, including all the dinosaurs.
Extinction	Extinction is the process in which groups of organisms (species) die out.
Eye	An eye is an axillary bud on an underground plant part such as a tuber (e.g., potato) or in the area where the stem joins the tuberous root (e.g., dahlia).
Fern	Ferns are non-flowering vascular plants with rhizomes that were plentiful during the Mesozoic Era and usually live in warm, moist areas. Ferns have fronds divided into leaflets.
Fertilizer	Fertilizer is material that is added to soil to increase is fertility and output. Fertilizers include manure, compost, and chemical mixtures.
Fibrous Root	A fibrous root is a type of primary root of a plant that has a lot of side branching (compare with tap root). Fibrous roots are the most common type of roots.
Filament	The filament is the part of the flower that holds the anther.
Flagellum	A flagellum is a long, thin, whip-like structure that is found on some organisms, including some unicellular algae. Flagella help propel the organism through water.
Flax	Flax (family Linaceae, genus Linum) is a flowering plant from cool, temperate areas. It has narrow, lance-shaped leaves and blue flowers - the plant grow to be up to about 1.5 to 2 feet tall. Flax is grown for its seeds (which yield oil) and linen fibre (a strong vegetable fibre that is made from the woody stalk of the flax plant).
Flora	The flora is all the plants that live in an area.
Flower	The flower is the reproductive unit of angiosperms. Flowers usually have carpels, petals, sepals, and stamens. Some flowers (called perfect flowers) have both male and female reproductive organs; some flowers (called imperfect flowers) have only male reproductive organs (stamens) or only female reproductive organs (ovary, style, and stigma). Some plants have both male and female flowers, while other has males on one plant and females on another. Complete flowers have a stamen, a pistil, petals, and sepals. Incomplete flowers lack one of these parts.
Foliage	Foliage is the leaves of plants.
Forb	A forb is a small, herbaceous (non-woody), broad-leaved vascular plant (excluding grasses, rushes, sedges, etc.). For example, wild flowers are a type of forb.
Forest	A forest is an area in which trees are the dominant plant.
Forest Floor	The forest floor is the lowest layer of a rainforest, extending from the ground to about 3 feet (1 m) high. This layer is teeming with animal life, especially insects. The largest animals in the rainforest generally live here.
Forest Succession	Forest or plant succession is the natural pattern of ecosystem growth and change over time for a particular environment. Plant life follows established patterns of growth and change after major disruptions, like fires, floods, agricultural damage, logging, etc. Generally, smaller, fast-growing herbaceous species and grasses grow first in an open field, followed in a few years by softwood tree seedlings and larger herbaceous species. As a young forest develops into a mature forest (30 to 70 years), an understorey of smaller hardwood trees develops. The final stage is a climax hardwood forest (100 plus years).
Fossils	Fossils are mineralized impressions or casts of ancient animals and plants. Fossils have been found on every continent on Earth.
Fronds	A frond is the fern-like (or feathery) foliage of a plant that has many divisions. Ferns and palms have fronds. Frond is also used to refer to the main part of a kelp plant (excluding the holdfast).
Fruit	A fruit is the part of a flowering plant that contains the seeds. Some fruits include apples, oranges, berries, maple pods, and acorns. Some fruit are fleshy and some are dry, like cotton (a dehiscent fruit) and sunflower (an indehiscent fruit). Not all fruit are edible. True (simple) fruits (like the tomato, coconut, watermelon, olive, lemon, and banana) develop from the wall of a single ovary. False (compound) fruits (like the strawberry, rosehip, and pineapple) develop from more than one pistil.
Fungus	Funguses (plural fungi) are organisms that obtain energy by breaking down dead organic material and that produce spores. Some fungi include mushrooms, toadstools, slime molds, yeast, penicillin, mold, and mildew.
Gametangium	(plural gametangia) A gametangium is a reproductive organ that is in some plants (especially algae, fungi, mosses, and ferns). The gametangium produces gametes (reproductive cells).
Genome	The genome of an organism is made up of the set of chromosomes that contain all of its genes.
Geotropism	Geotropism is a plant's reaction to gravity in which the roots go towards the pull of gravity, and the shoots go in the opposite direction.
Germination	Germination is the beginning of growth of a plant from its seed.
Granum	(plural grana) A stack of thylakoid disks within the chloroplast is called a granum.
Grass	Grasses are a group of flowering plants (angiosperms) that belong to the family Graminae.
Greenhouse Effect	The greenhouse effect is an increase in the temperature of a planet as heat energy from sunlight is trapped in the atmosphere. Excess carbon dioxide and water vapour increase this effect. The greenhouse effect is strong on Earth, maintaining (and possible exacerbating) warm temperatures.
Guard Cell	Each stoma has two crescent-shaped guard cells that control the size of the opening of the stoma using turgor pressure. This changes the amount of water vapour and other gases that can enter and leave the plant.
Gum	Gum is a sticky substance that is secreted by some plants. Gum hardens when it dries.
Gymnosperms	Gymnosperms (meaning "naked seeds") are seed-bearing plants that that don't produce flowers. They release pollen into the air to the female ovule, causing fertilization. Their seeds develop without a protective covering. Conifers (like pines, redwoods, and fir), gingkos, seed ferns, cycadeoids, and cycads are gymnosperms.
Habitat	A habitat is a space (which includes food, water and shelter) suitable for the survival and reproduction of an organism.
Halomorphic	Halomorphic characteristics are adaptations to saline (salt water) environments.
Halophyte	A halophyte is a plant that has adapted to salty soils.
Haploid	A haploid cell has only half the number of chromosomes that the other cells of that organism have (most are diploid). Gametes (like the sperm and the egg) are haploid
Hardwood	Hardwood trees are trees whose wood is dense, strong, and relatively non-absorbent of water. These slow-growing trees include oak and maple. Hardwood trees have broad leaves (and not needles).
Haustorial Root	A haustorial root is one that absorbs water and nutrients from another plant (and not the soil).
Herb	An herb is a seed plant that does not have a woody stem. Every year, herbaceous plants produce a completely new stem. Herbaceous plants are generally short lived and relatively short (compared to woody plants). Some herbaceous plants include the banana, grasses, and forbs.
Herbicide	An herbicide is a chemical that kills certain plants. Herbicides are usually intended to kill weeds.
Herbivores	Herbivores (also called primary consumers) are animals that eat plants.
Hermaphrodite	A hermaphrodite is a plant that has both female and male reproductive organs.
Heterophyllous	A heterophyllous (meaning "other leaf") plant or branch has two or more different leaf shapes on it. Although these leaves have different shapes, they have similar internal anatomical organizations.
Hilum	The hilum is the scar on a seed coat at the location where it was attached to the plant's stalk during development.
Holdfast	A holdfast is the root-like structure of kelp that holds the base of the plant in place on the sea floor. Unlike real roots, however, the holdfast does not obtain and supply nutrients to the rest of the plant.
Hormone	A hormone is a chemical in plants (and other organisms) that regulates the plant's growth, reproduction, and other functions.
Horticulture	Horticulture is the science of growing fruits, vegetables, flowers, and ornamental plants
Humus	Humus is the rich, organic portion of the soil. It is composed of decayed plant and animal materials.
Hybrid	A hybrid is the offspring of two organisms that belong to different breeds, varieties, species or genera.
Hydrologic Cycle	The Hydrologic Cycle (also known as the water cycle) is the journey water takes as it circulates from the Earth to the sky and back again.
Hydrophyte	A hydrophyte is a plant that grows in water or in water-logged soil. Hydrophytes have a reduced root system, reduced support and vascular systems, and specialized leaves. Some hydrophytic plants include waterlilies and Wolffian (which is the smallest flowering plant). Anchored hydrophytes have a rooting system that is embedded in the soil and they often have floating leaves. (Compare with mesophytes and xerophytes.)
Hydroponics	Hydroponics is a method of growing plants in water that contains dissolved nutrients (instead of in soil).
Hypocotyl	The hypocotyl is the part of the stem of a sprouting plant that is above the root and below the stalk of the cotyledons (seed leaves).
Imbibition	Imbibition is the process in which a seed takes up water from its surrounding and swells. This powerful process precedes germination and can spit the seed coat.
Imperfect Flower	An imperfect flower has either male (stamen) and female (ovary) reproductive organs on the same flower, but not both. (Compare with perfect flowers.)
Incomplete Flower	An incomplete flower is missing one of the four major parts of the flower, the stamen, pistil, petals, or sepals.
Indehiscent	A fruit that remains closed at maturity is indehiscent. Nuts, acorns, sunflowers, grains, and maple pods are examples of indehiscent fruits.
Indigenous	An indigenous organism is one that lives naturally in a particular region and were not introduced there by man.
Inferior Ovary	An inferior ovary (also called an epigynous ovary) is an ovary located below the flower parts (the calyx, corolla, and androecium). The flower parts are attached to the top of the ovary.
Inflorescence	Inflorescence is a type of flower in which there is more that one flower in a single structure.
Internode	The part of a plant's stem between two nodes is the internode - the distance along the stem between the leaves.
Jungle	A jungle is a rainforest or a forest whose canopy trees have been logged (cut), causing lush growth on the forest floor (also known as a secondary forest).
Juvenile	A juvenile plant is in an early phase of plant growth in which it increases in size but has not yet flowered.
Kelp	Kelp is a plant that lives in the oceans. This cold-water seaweed belongs to the family Laminariaceae. Kelp is a large, floating plant that grows in large masses (called kelp forests) and is held to the sea floor by a holdfast. Kelp is usually brown. Kelp is used by people as food, a food additive, fertilizer (when reduced to ash), and as an ingredient in many other products.
Kelp Forest	A kelp forest is a marine ecosystem (a biome) that is dominated by large kelp plants. These oceanic forests grow in cold and temperate waters, especially along the western coasts of the continents.
Lamina	The lamina is the blade of a leaf.
Lanceolate	Lanceolate leaves are shaped like a lance; they have a broad base and taper to a point.
Latex	Latex is a milky substance that is tapped from rubber trees
Leaf	A leaf is an outgrowth of a plant that grows from a node in the stem. Most leaves are flat and contain chloroplasts; their main function is to make food energy through photosynthesis. The first leaf to grow from a seed is called the cotyledon.
Leaf Abscission	Leaf abscission is the normal separation of a leaf from a plant. Abscisic acid is the plant hormone involved in leaf abscission.
Leaf Axil	The leaf axil is where the petiole of the leaf attaches to the stem.
Leaf Dimorphism	Having two types of leaves on the same plant.
Leaf Gap	A leaf gap is a break or gap in the plant's stele (cylinder of vascular tissue) at the base of a node (where a leaf is). In the absence of a leaf, there would be no gap, i.e., an unbroken cylinder of vascular tissue
Leaflet	A leaflet is part of a compound leaf. Each leaflet looks like a small leaf.
Leaf Scar	A leaf scar is mark on a plant's stem that is left where a leaf was once attached.
Legume	A legume is a flowering plant that bears its protein-rich seeds in pods and can fix nitrogen from the soil (due to the symbiotic root bacteria, rhizobia). Some legumes include lentils, beans, clover, alfalfa, lespedezas, vetches, kudzu, and peas.
Lemma	A lemma is a bract (a reduced, leaf-like structure associated with a flower) in a grass spikelet that is located below the stamens and pistil of the flower.
Lentical	A lenticel is a small pore in the bark of a tree through which gas exchange occurs.
Lignotuber	A lignotuber is a root or woody stem base that stores water.
Lignule	Lignules (which means tongue) are the two small flaps at the base of a monocot's leaf that wrap around the stem.
Longitudinal Striate Venation	Longitudinal Striate venation is a vein pattern found in monocots leaves. A leaf with longitudinal striate venation has its veins arranged almost parallel to one another, running the length of the leaf (also called parallel venation).
Lysosomes	Lysosomes are organelles within plant cells (and other eukaryotic cells) that contain digestive enzymes and is involved with the digestion of food. A lysosome fuses with a vascular membrane that contains food, and the lysosome's enzymes digest the food, breaking the food down into its components.
Mangrove	Mangroves are tropical evergreen trees and shrubs. They live near the shore in tropical marshes and tidal shores with their adventitious roots in the salt water.
Mangrove Forest	A mangrove forest (also called a mangrove swamp) is an expanse of mangrove trees. These trees live near the shore in tropical marshes and tidal shores with their adventitious roots in the salt water.
Margins	The margins of a leaf are its edges, which very from plant to plant. The margins can be smooth, serrated, or toothed; they can also be lobed or entire.
Medullary Rays	Medullary rays (also called wood rays) are bundles of cells that radiate from the centre of a tree like the spokes of a wheel (they are most easily seen in the cross section of a tree trunk). They store food and transport it horizontally within the tree.
Meiosis	Meiosis is a process in which an eukaryotic cell's (diploid) nucleus divides twice and produces four daughter cells (called gametes or reproductive cells), each of which have half the genetic complement of the parent cell (they are haploid). This process was named by Farmer and Moore in 1905.
Meristem	The meristem is a group of plant cells that can divide indefinitely. The meristem provides new cells for the plant.
Mesophyll	Mesophyll is the internal tissue of a photosynthetic leaf.
Mesophyte	A mesophyte is a plant that has moderate water requirements. (Compare with hydrophytes and xerophytes.)
Mildew	Mildew is a parasitic, filamentous fungus that grows on a host plant.
Mineral	A mineral is a naturally-occurring solid of definite chemical composition whose atoms usually form a regular pattern.
Mitochondrion	Mitochondria (the plural of mitochondrion) are organelles within most eukaryotic cells - they power cells by generating energy (in the form of ATP, adenosine triphosphate) by breaking down glucose (a type of sugar). Mitochondria are self-replicating and bound by membranes.
Monocot	A monocot is a type of flowering plant (an angiosperm) whose seed has one embryonic leaf (cotyledon). The leaves of monocots generally have parallel venation (the veins are parallel to one another). The roots of monocots are usually fibrous and the flower parts are often in multiples of three.
Monoculture	Monoculture is a system of agriculture in which a single type of crop is grown in an area.
Monoecious	Monoecious plants have the male and female reproductive organs on the same plant. (Compare with dioecious.)
Monopodial	Monopodial (meaning "one foot") is a type of plant growth in which the plant has a single main stem. Compare with sympodial.
Moss	Moss is a small, low-growing, green plant that has a stem, leaves, and rhizomes (but no vascular system). Mosses reproduce with spores or by forming gametes.
Mucigel	Mucigel is a slimy, protective substance that is secreted by plant roots.
Mushrooms	Mushrooms are fast-growing fungi (they are not plants). They grow in dark, damp places and reproduce via spores.
Mycorrhizae	Mycorrhizae is a fungus that grows in a symbiotic relationship with the roots (or rhizoids) of a plant.
Natural Selection	Natural selection is the process in which some organisms live and reproduce and others die before reproducing. Some life forms survive and reproduce because they are better suited to environmental pressures, ensuring that their genes are perpetuated in the gene pool.
Naturalist	A naturalist is a person who studies plants and animals.
Nectar	Nectar is the sweet liquid produced by many flowers. Nectar attracts many insects (like butterflies and bees) who go from flower to flower sipping nectar, causing the pollination of the flowers.
Needle	A needle is a long, thin, pointed, needle-shaped leaf, like that of the pine. The word acicular is sometimes used to describe needles.
Nitrogen Fixing	Some bacteria (rhizobia) are nitrogen-fixing; they transform nitrogen gas in the atmosphere into a form that can be used by plants.
Node	A node is a part of the stem of a plant from which a leaf, branch, or aerial root grows.
Nodule	A nodule is a small, rounded knot on some leguminous plant roots which contain nitrogen-fixing bacteria (rhizobia). For example, peanut plant roots have nodules
Noxious Weed	A noxious weed is a plant that is considered by local authorities to be a problem, growing where it is not wanted.
Nucleus	The nucleus is a membrane-bound organelle in each plant cell which contains the genetic material of the cell (DNA in chromosomes). It is where DNA (deoxyribonucleic acid) replicates itself, and where RNA (ribonucleic acid) is made. The plural of nucleus is nuclei.
Nuclear Membrane	The nuclear membrane is double membrane that surrounds the nucleus of the cell.
Organ	An organ is a specialized tissue (a group of cells) in multicellular organisms that performs a particular function. For example, the ovary is an organ that produces ovules.
Organelle	An organelle is membrane-bound structure within a plant's cell (and all eukaryotic cells) where specialized metabolic tasks occur. Some organelles include the nucleus, nucleolus, mitochondria, the ER (endoplamic reticulum), and lysosomes.
Osmosis	Osmosis is a process in which water moves across a semi-permeable membrane in order to equalize the concentration of the solution on both sides. For example, water will move across a cell membrane from areas of low salinity (a hypotonic solution) to areas of high salinity (a hypertonic solution) to equalize the concentrations (and create two isotonic solutions).
Ovary	An ovary is a female reproductive organ in plants that produces ovules.
Ovule	An ovule is the female reproductive cell of flowering plants and cone-bearing plants. After the ovule is fertilized by the male pollen, the ovule becomes a seed.
Palisade Parenchyma	The palisade parenchyma (also called the palisade layer) is a layer of tightly-packed, tube-shaped, chlorophyll-containing cells (chlorenchyma) that is the major photosynthetic layer of a leaf. The palisade layer is located in the upper mesophyll of a leaf (just beneath the upper dermal layer of the leaf).
Palm	A palm is an evergreen tree and a monocot.
Palmate	A palmate leaf has a hand-like structure. It has more than three lobes that branch from a single point at the base of the leaf.
Palmate Venation	A leaf with palmate venation has the main veins arising from a point at the base of the leaf.
Parallel Venation	A leaf with parallel venation (also called longitudinal-striate venation) has its veins arranged almost parallel to one another.
Parted	A parted (also called cleft) leaf is one in which the margins between the irregular teeth go more than halfway to the midrib.
Pedicel	A pedicel is plant stalk that attaches a single flower or fruit to the main branch of the inflorescence.
Peduncle	A peduncle is plant stalk that bears an inflorescence or single flower.
Perenate	A plant that perennates lives from year to year (it is a perennial).
Pernnial	A perennial plant has a life cycle that lives for more than two years. Perennials usually flower each year.
Perfect Flower	A perfect flower has both male (stamen) and female (ovary) reproductive organs on the same flower. (Compare with imperfect flowers.)
Perianth	The perianth (which means "around the anthers") is the sepals and petals of a flower.
Pericarp	The pericarp is the fruit wall that develops from the ovary wall. The pericarp is divided into the endocarp, mesocarp and exocarp.
Pericarpal	The pericarpal is the upper part of the flower stem, the receptacle, and the lower part of the pistil.
Petal	A petal is one of the leafy structures that comprise a flower. Petals are often brightly-coloured and have many different shapes. They are located between the sepals and the flower's reproductive organs.
Petiole	A petiole is a leaf stalk. On a compound leaf, the petiole extends from the stem to the first set of leaflets. A leaf without a petiole is sessile.
Petrification	Petrification is the process in which an organic tissue turns to stone. The original materials are replaced by minerals.
Phloem	Phloem is plant tissue that conducts nutrients (food) through the plant. In woody-stemmed plants, the phloem is the inner layer of the bark. (Compare with xylem.)
Photosynthesis	Photosynthesis is the process in which plants convert sunlight, water, and carbon dioxide into food (sugars and starches), oxygen and water. Chlorophyll or closely-related pigments (substances that colour the plant) are essential to the photosynthetic process.
Phototropism	Phototropism is the bending of a plant in response to sunlight. This reaction is caused by the growth hormone auxin that is contained in the stem.
Pinnate Compound Leaf	A pinnate compound leaf is made up of many small leaflets arranged in pairs on either side of a long central midrib (the rachis). There is often a single terminal leaflet at the end of the midrib.
Pinnately lobed Leaf	Pinnately lobed leaves have many lobes arranged along the midrib.
Pinnate Ventation	A leaf with pinnate venation has its veins arranged in pairs coming from a main central midrib vein (the rachis).
Pistil	The pistil is the central set of female reproductive organs in a flower. The pistil is composed of one or more carpels and produces the ovule.
Pistillate	Pistillate flowers have a pistil or pistils.
Pith	The pith is parenchyma cells at the centre of the primary stem of a dicot.
Plant	A plant is a member of the kingdom Plantae, a living organism that undergoes photosynthesis
Plant Succession	Plant succession is the natural pattern of ecosystem growth and change over time for a particular environment. Plant life follows established patterns of growth and change after major disruptions, like fires, floods, agricultural damage, logging, etc. Generally, smaller, fast-growing herbaceous species and grasses grow first in an open field, followed in a few years by softwood tree seedlings and larger herbaceous species. As a young forest develops into a mature forest (30 to 70 years), an understorey of smaller hardwood trees develops. The final stage is a climax hardwood forest (100 plus years).
Plasma Membrane	A plasma membrane (also called the cell membrane or plasmalemma) surrounds each cell and separates it from the environment. In pants, the cell membrane contains cellulose (a carbohydrate).
Platysperms	Platysperms (meaning "flat seeds") are plants with flattened ovules. Platysperms include gingkos, conifers, glossopterids, and cordaites.
Plumule	The plumule is the shoot of a plant embryo (in the seed before germination).
Pneumatophore	A pneumatophore is an air-transporting vessel in plants.
Pod	A seed pod is an elongated, two-sided vessel that contains several fertilized seeds. It is a dehiscent fruit or pedicarp - the pod splits open when the seeds are mature. Beans and peas are some plants that have pods.
Pollen	Pollen is the male reproductive cell of flowering plants and cone-bearing plants. Pollen grains are produced in the anther of a flower.
Pollen Tube	After the male's pollen grains have landed on the stigma during fertilization, pollen tubes develop within the style. The pollen tubes transport the sperm from the grain to the ovum (where fertilization of the egg occurs and the seeds will develop).
Pollination	Pollination is the process in which the male's pollen fertilizes the female's ovule and creates a seed; the pollen is transferred from the male's anther to the female's stigma. Pollination is effected by the wind, insects, hummingbirds, etc.
Pollinium	A pollinium (or pollinia) is a mass of fused pollen grains that is produces by a single anther. This mass sticks together and during pollination is transported as a single unit. Orchids have polliniums.
Prickle	A prickle is a sharp outgrowth of a plant's epidermis (outer skin). Prickles are easily broken off a plant. Roses have prickles.
Primary Root	The primary root is the first root of a plant to develop in the germinating seed. The primary root develops from the radicle of the embryo. It is also called the taproot
Rachis	The rachis is the midrib of a leaf. It is usually continuous with the petiole and is often raised above the lamina (the leaf blade). On a compound leaf, the rachis extends from the first set of leaflets (where the petiole ends) to the end of the leaf.
Respiration	C6H12O6 + 6O2 = 6CO2 + 6H2O + ATP Respiration is a process in which energy is generated in cells. In respiration, glucose (a type of sugar) and oxygen are converted into carbon dioxide, water and ATP (adenosine triphosphate). Respiration takes place in the mitochondrion of both plant and animal cells.
Reticulate Venation	A leaf with reticulate venation has its veins arranged in a pattern such that larger veins give rise to progressively smaller veins. The end branches of the veins define small areas called aeroles.
Rhizome	A rhizome is a thick, horizontal underground stem (not a root) of a plant that grows close to the ground. Rhizomes have nodes and scale-like leaves; roots form on the lower surface and new shoots can form at nodes. Ferns, mosses, horsetails, ginger, irises, and some grasses have rhizomes.
Riparian Forest	A riparian forest is situated by a river bank or other body of water.
Root	A root is a plant structure that obtains food and water from the soil, stores energy, and provides support for the plant. Most roots grow underground.
Root Cap	The root cap is a cap-shaped structure at the ends (tips) of the roots. It covers and protects the apical meristem (the actively growing region) of the root.
Root Hairs	Root hairs are very thin, hair-like roots that are extensions of the root's epidermis. Root hairs have a large surface area and absorb water and minerals for the plant.
Root Tip	The root tip is the tip of the root and contains the root cap and the apical meristem (the actively growing region).
Sap	Sap is a liquid that circulates within the sapwood of woody plants. Sap rises up from the roots. Sap contains water and minerals; in the spring it also contains sugars (and stimulates the growth of the tree).
Sapling	A sapling is a small, young tree.
Sapwood	Sapwood is the outer layer of wood in a tree and contains living cells. Sap circulates within the sapwood of woody plants.
Sclerenchyma	Sclerenchyma is a supportive and protective tissue found in plants. Sclerenchyma is composed of hard, thick, dry cells.
Sclerophyllous Plants	Sclerophyllous plants are small plants that have hard, thickened leaves and have a relatively short distance along the stem between the leaves (short internodes). Sclerophyllous plants are often from dry areas.
Seasons	There are four seasons in the year: winter, spring, summer, and autumn.
Seaweed	Seaweed is a type of aquatic plant that obtains its energy via photosynthesis. Seaweed (like kelp) are not true plants. Seaweeds are usually green, brown, or red.
Seed	The seed is the reproductive unit of some plants.
Seed Coat	The seed coat is the outer, protective layer covering the seed. The seed coat is formed from the two integuments in the developing seed.
Seed Dispersal	Seeds are dispersed (spread) by many different methods, including floating on the wind (e.g., dandelions), floating in the water (e.g., coconut, sedge), hitching a ride on an animal (e.g., cranesbill), or being eaten (and then expelled) by a seed dispersing animal (e.g., many fruits).
Seed Disperser	A seed disperser is an animal that eats seeds (usually contained in fruit) but does not harm the seed. The seed is excreted in the stool, and the seed is spread away from the parent plant. Some seed dispersers include the kereru (a pigeon from New Zealand) and the cassowary (from Australia and New Guinea).
Seed Ferns	Seed ferns (Pteridosperms) were primitive seed plants (not ferns at all) that lived in swampy areas from the Mississipian Epoch through the Mesozoic Era. They had woody stems studded with dried out leaf bases. The tops had fern-like fronds which bore seeds.
Seed Pod	A seed pod is an elongated, two-sided vessel that contains several fertilized seeds. It is a dehiscent fruit or pedicarp - the pod splits open when the seeds are mature. Beans and peas are some plants that have pods.
Seed Predator	A seed predator is an animal that eats and destroy seeds instead of eating the fruit and leaving the seed or dispersing the seed in the stool. Parrots are seed predators. Seed predators limit the number of viable seeds.
Self Pollination	Self-pollination is the transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant.
Sepal	The sepals are small leaves located directly under a flower - they are the outermost part of a flower. Collectively, the sepals are called the calyx.
Sessile	A leaf without a petiole (a leaf stalk) is sessile.
Sexual Dimorphism	Sexual dimorphism is characteristic of having two different forms, one for the males and another for the females of a species.
Shoot	A shoot is new growth on part of a plant.
Simple Leaf	A simple leaf is a leaf with only one lamina for each petiole (that is, each leaf blade has one stem).
Siphonostele	A siphonostele is a type of stele that consists of a cylinder of vascular tissue (xylem and phloem) that surrounds the central pith tissue.
Soil	Soil is a natural, constantly-changing substance that is made up of minerals, organic materials, and living organisms. Plants grow in soil.
Solar Radiation	Solar radiation is the heat and light that comes from the sun.
Spike	A spike is a flower stalk, an ear of grain (such as corn or wheat), or an inflorescence of un-stalked flowers.
Spikelet	A spikelet is a secondary spike found in grasses; it is a cluster of two or more flowers in the inflorescence.
Spine	A spine is a sharp, modified leaf, scale, or stipule. Cacti have spines.
Spore	A spore is a single-celled reproductive unit of some organisms (cryptogams like mushrooms, ferns and mosses). Functionally, a spore is similar to a seed but it does not contain an embryo). Spores are usually encapsulated by a rigid wall.
Sprout	A sprout is a very young plant (newly germinated) or the new growth on a plant (a shoot).
Stamen	The stamen is the male reproductive parts of a flower. It consists of the filament and the anther, which produces pollen.
Stele	A stele is the central cylinder of vascular bundles in stems and roots.
Stem	A stem is the axis of a plant; it may be above or below the ground.
Stigma	The stigma is part of the pistil, the female reproductive tissue of a flower. The stigma receives the male pollen grains during fertilization.
Stipe	A stipe is a stem-like structure in some plants, like some kelp and fungi.
Stipules	Stipules are small, paired appendages (sometimes leaf-life) that are found at the base of the petiole of leaves of many flowering plants.
Stolon	A stolon is an above-ground stem that has buds that sprout to form new shoots, forming a new, genetically-identical plant. Strawberry plants have stolons.
Stoma	A stoma (the plural is stomata) is a pore (or opening) in a plant's leaves. Most of the stoma is on the underside of the leaf. Guard cells open and close the stoma using turgor pressure, controlling the loss of water vapour and other gases from the plant.
Striate Venation	Striate venation is a vein pattern found in monocots leaves. A leaf with striate venation has its veins arranged almost parallel to one another.
Stroma	The stroma is part of the chloroplasts in plant cells, located within the inner membrane of chloroplasts, between the grana.
Style	The style is part of the pistil, the female reproductive tissue of a flower. The style is a long tube on top of the ovary below the stigma. After the male's pollen grains have landed on the stigma during fertilization, pollen tubes develop within the style. The pollen tubes transport the sperm from the grain to the ovum (where fertilization of the egg occurs and the seeds will develop).
Sucker Root	A sucker root is a root that emerges from the ground and sends up a shoot which supports the plant.
Tap Root	The tap root is the main root of some plants; the tap root extends straight down under the plant with very little side branches (compare with fibrous root).
Thylakoid Disks	Thylakoid disks are disk-shaped membrane structures in chloroplasts that contain chlorophyll. Chloroplasts are made up of stacks of thylakoid disks; a stack of thylakoid disks is called a granum. Photosynthesis (the production of ATP molecules from sunlight) takes place on thylakoid disks. Thylakoid means 'sac-like' in Greek.
Transpiration	Transpiration is the process in which plants lose water through pores in their leaves (these openings are called stomata). As water is lost from the plant, the plant takes up more water (and minerals) through its roots. The rate of transpiration varies as the conditions of the plant change and is controlled by the opening and closing the stomata.
Tree	A tree is a plant that produces wood (made by xylem cells). These tall plants grow taller each year.
Tree Rings	By counting the number of tree rings in a tree's trunk, you can tell how old the tree was.
Trunk	The trunk of a tree is the stem that supports the crown.
Tuber	A tuber is a modified root that stores nutrients. Potatoes are tubers.
Turgor Pressure	Turgor pressure is the force that is exerted on a plant's cell wall by the water (in the cytoplasm) within the cell. The water presses against the cell wall from within, giving the plant cell rigidity, helping it keep its shape. Turgor pressure is the mechanism that changes the shape of the guard cells that open a plant's stomata, pores located on the underside of leaves.
Unicellular	Unicellular organisms consist of a single cell. (Compare with multicellular.)
Vacuole	A vacuole is a large, membrane-bound space within a plant cell that is filled with fluid. Most plant cells have a single vacuole that takes up much of the cell. It helps maintain the shape of the cell.
Vascular Plant	A vascular plant has specialized pipelines that carry water and nutrients around the plant. Club mosses, ferns, horsetails, gymnosperms, and flowering plants are vascular plants.
Vascular Tissue	Vascular tissue is tissue that transports water and nutrients through a plant. Xylem and phloem are types of vascular tissue
Vegetable	A vegetable is a plant whose stem, leaves, tubers, roots, bulbs, or flower is a food source for people. Some examples of vegetables include carrots, eggplant, potatoes, spinach, broccoli, onion, and asparagus.
Vegetative Propagation	Vegetative propagation is a method of reproducing asexually; the offspring have the same genetic makeup as the parent.
Vegetative State	The vegetative state is the stage in a flowering plant's life cycle before the appearance of its fruiting structures.
Vein	A vein is a vascular structure (xylem and phloem cells surrounded by the bundle sheath) in a leaf that provides supports for the leaf and transports both water and food. The veins on monocots are almost parallel to the margins of the leaf. The veins of dicots radiate from a central midrib.
Veinlet	A veinlet is a small vein. Veinlets are located toward the margins of the leaf.
Venation	Venation is the arrangement of veins in a leaf. Some different cenation patterns include pinnate, palmate, and parallel
Vine	A vine is a plant that needs support as it grows. Some vines grow by twining around other objects for support (e.g., morning glory), some use tendrils (modified shoots) to attach to objects (e.g., peas and vetch), and others send out aerial roots, often with suckers (e.g., poison ivy).
Xerophyte	A xerophyte is a plant that is adapted to very dry conditions (like deserts and the emergent level of the rainforest). Succulents, bromeliads and cacti are xerophytes. Their adaptations include small or absent leaves, small, sunken stomata, and thick cuticles. (Compare with hydrophytes and mesophytes.)
Xylem	(pronounced ZIE-lem) Xylem is a tissue in plant stems and roots. Xylem transports water and minerals upwards from the roots to the stem, via capillary action. Xylem is strong and also provides support to the plant. (Compare with phloem.)

Document Actions

Careers Info