- - A - -

Abaxial/Adaxial: This refers to whether the surface faces away from or toward the axis of the origin

Achene: A small, dry, one-seeded fruit in which the seed is not adnate to the fruit wall; found in sedges and other plant families

Agrostology: The study of grasses, especially their taxonomy

Angiosperm: A seed borne in a vessel; and so one of a group of flowering plants whose seeds are borne with a mature ovary (fruit)

Annual: Completing growth, flowering and fruiting within one year, the plant then dying

Articulated: Jointed, forming joints that may break apart (disarticulate) from each other

Autotroph: An organism that is able to synthesize its own food from its environment using inorganic elements and the sun's energy

Auricle: An ear-shaped extension from one or both sides of the base of the leaf blade or apex of the leaf sheath

Awn: A stiff projection usually from the lemma or glume either from the tip or the abaxial surface. If bent like a knee the awn is 'geniculate'. Awns that hydrate are called 'hygroscopic' and those that do not 'passive'.

Axil: The angle formed between a culm (or stem) and an attached leaf

- - B - -

Bearded: With a tuft of hairs, used especially to describe the callus in grasses

Blade: The commonly expanded, flat, green, photosynthetic part of the leaf; may be reduced, modified in various ways, or absent

Bract: A modified, usually reduced leaf like structure near the terminus of the culm

- - C - -

Callus: The hard, commonly pointed base of the floret or the spikelet, just above the point of disarticulation; may be hairy

Cereal Grain: Any of the economically important species of grasses, the grains of which are used for human consumption; for example, wheat, rice, maize, barley, oats, rye and millet

Chromosome: The organelle that carries the genes. Eukaryotic chromosomes are visualized as threads or rods of chromatin, and are inclosed in a nucleus; bacterial chromosomes consist only of a closed circle of DNA

Cool-Season Grass: Grasses which make the major portion of its growth in spring under an optimal temperature range of 15-25C, and requiring 1/5 full sunlight for full photosynthesis

Cotyledons: The seed leaf. The first leaf or leaves of the embryonic plant; typically one in monocotyledons and two (rarely more) in dicotyledons, providing the food for the developing plant

Culm: The aerial stem of a grass plant; commonly erect but may be leaning or creeping

- - D - -

Diatomaceous Earth: A geologic deposit of fine, greyish, siliceous material composed chiefly or wholly of the remains of diatoms. It may occur as a powder or as a porous, rigid material

Dicotyledon: A member of one of the two major groups of flowering plants, characterized by having two cotyledons in the embryo, the capacity for secondary growth, and net-veined leaves; often referred to as dicots

Diploid: Having two sets of chromosomes - (2n)

Disarticulation: Separation of structures at joints or nodes

Dominant Species: Plants or groups of plants which, in terms of their abundance, coverage, or size, have large influence or control upon the conditions of existence for associated species

Dormancy: A special condition of arrested growth in which the plant and plant parts such as buds and seeds do not begin to grow without special environmental cues.

Dorsal: Of the outer or back side of a structure; in grasses, a type of compression, in which spikelets or florets are flattened from front to back

Double Fertilization: The fusion of the egg and sperm (resulting in a 2n fertilized egg, the zygote)and the simultaneous fusion of the second male gamete with the polar nuclei (resulting in a 3n primary endosperm nucleus)

- - E - -

Embryo: The miniature plant that will produce the first root and first shoot as the seed germinates

Endosperm: A starchy or oily tissue that provided nutrients for the developing and/or germinating embryo; in grasses, this is starchy and commonly occupies a relatively large part of the seed; found only in angiosperms

Enzyme: A protein that is capable of speeding up specific chemical reactions by lowering the required activation energy, but is unaltered itself in the process; a biological catalyst

Epi - : A Greek prefix meaning "upon" or "above"

- - F - -

Fascicle: Bunch or cluster, commonly used to describe the arrangement of branches or spikelets

Floret: The unit of a grass spikelet, consisting of a bisexual or unisexual flower enclosed by a palea in turn enclosed by a lemma

Forb: Any herbaceous plant other than those in the grass, sedge, and rush families

Fruit: In flowering plants in general, the ripened ovary wall containing one to many seeds; in grasses the fruit is the grain

- - G - -

Gamete: A haploid reproductive cell; gametes fuse in pairs, forming zygotes, which are diploid

Geniculate: Abruptly bent, as at the elbow or knee; in grasses, commonly used to describe awns, branches, or culms

Germination: The beginning or resumption of growth by a spore, seed, bud, or other structure

Gynoecium: Collective term for the female parts of a flower, the pistils

- - H - -

Haploid: Having only one set of chromosomes (n), in contrast to diploid (2n)

Herbaceous: With no persistent aboveground stem, without secondary growth, not woody; includes most grasses

Hypo - : A Greek prefix meaning "under" or "less"

- - I - -

Imbricate: Overlapping, like the shingles on a roof

Inflorescence: In grasses; a spikelet-bearing branch or system of branches; the uppermost leaf below the whole inflorescence is commonly an ordinary foliage leaf, but some are modified as a spathe

Internode: The segment of a stem bounded by two nodes

- - K - -

- - L - -

Lateral: Of the side or to the side, as in the wings of tissue in either side of the midrib of a lemma; in grasses, a type of compression, in which spikelets or florets are flattened from side to side, leaving the keels of the lemmas edgewise

Leaf: The commonly photosynthetic organ of a plant; in grasses, at a minimum this consists of a sheath, inner ligule, and a blade

Leaflet: One of the parts of a compound leaf

Lemma: The lower bract of the two that enclose the grass flower, typically with an odd number of nerves

Ligule: An extension of the foliage leaf sheath on the inner side (the side facing the culm) beyond the junction with the blade; this structure may be membrane like or a rim of hairs or rarely lacking entirely

- - M - -

Membranaceous: Thin, membrane-like in texture

Monocotyledon: A member of one of the two major groups of flowering plants, characterised by having one cotyledon in the embryo, lack of secondary growth, and leaves with the major veins parallel; often referred to as monocots

Morphology: The interrelated study of form, structure and development

- - N - -

Node: The place on a stem (or other axis) where a leaf is attached; joint

- - O - -

Obtuse: Blunt or rounded, forming an angle of more than 90

Ovary: The lower, commonly somewhat swollen part of the pistil containing the ovule(s)

Ovule(s): The immature, unfertilized seed, may be one or many per ovary

- - P - -

Palea: The uppermost, commonly two-keeled bract enclosing the grass flower

Panicle: In grasses, a type of inflorescence in which the main axis branches and the spikelets are borne on pedicels

Peat Moss: Unconsolidated soil material consisting largely of undecomposed, or only slightly decomposed organic matter accumulated in conditions of water saturation, the vegetation becomes submerged

Pedicel: The stalk of a spikelet

Peduncle: The stalk of the inflorescence

Perennial: Growing and surviving over several or many years, flowering and fruiting annually or not

Perfect: Including both sexes, as in a bisexual flower

Pericarp: The fruit wall, derived from the ovary wall

Petiole: The stalk of a leaf in dicotyledons

Pistil: The female part of the flower, consisting of an ovary, a style, and one to several stigmas

Plumule: The first bud of an embryo; the portion of the young shoot above the cotyledons

Polymer: A large molecule composed of many similar molecular subunits; a compound needed to pull together other molecules to create a more complex structure

- - R - -

Raceme: a type of unbranched inflorescence in which the pediceled spikelets sit directly on the rachis

Rachilla: The main axis of the spikelet, articulated and breaking up into joints in many species, and continuous in others

Radicle: The embryonic root

Respiration: An intercellular process in which molecules, are oxidized with the release of energy. The complete breakdown of sugar or other organic compounds to carbon dioxide and water is termed aerobic respiration, although the first steps of this process are anaerobic

Rhizome: An underground stem with nodes and internode, bearing scale leaves (these commonly consisting of just a sheath) at the nodes, the whole structure whitish

Rhizosphere: The zone of biological activity surrounding the young plant roots; the number of organisms in the area may be as much as 100 times greater than elsewhere in the soil

- - S - -

Scarification: The intentional damage or removal of the seed coat

Scutellum: The single cotyledon of a grass embryo, specialized for absorption of the endosperm

Seed: A mature, fertilized ovule, containing an embryo and, in grasses, commonly copious endosperm, all enclosed in a seed coat

Seedling: A young sporophyte, which develops from a germinating seed

Sessile: Lacking a pedicel or stalk

Sheath: The lower part of the foliage or culm leaf that clasps or encircles the culm; the margins free and overlapping in most grasses, but in some species the margins are fused, forming a tube

Spathe: Modified leaf just below the inflorescence, commonly with a reduced blade and expanded sheath; in grasses, most are green or brown but may be tinted with pink, red, or purple

Spike: A type of unbranched inflorescence in which the sessile spikelets sit directly on the rachis

Spikelet: The basic unit of the grass inflorescence, commonly consisting of a pair of glumes and one to many florets

Stamen: The male, pollen-bearing part of the flower, consisting of a filament and an anther

Sterile: Lacking functional male and/or female flower parts, as in sterile florets; also used to describe lack of seed production

Stigma: The terminal branch or branches of the pistil where pollen lands

Stipule: An appendage, often leaf like, that occurs on either side of the basal part of a leaf, or encircles the stem, in many kinds of flowering plants

Stolon: A decumbent or prostrate culm growing on the soil surface, bearing scale leaves (many with a sheath and a reduced blade) at the nodes, the whole structure green

Stratification: The process of exposing seeds to low temperatures for an extended period before attempting to germinate them at warm temperatures

- - T - -

Terete: Round in cross-section; cylindrical

Terminal: At or produced from the tip of an axis

Tiller: An underground or ground-level, lateral aerial shoot that is commonly erect and derived from the main or parent culm; a parent culm may produce multiple tillers

Triad: Cluster of three

Triploid: Having three complete sets of chromosomes per cell (3n)

- - U - -

Unilateral: One-sided

- - V - -

Vermiculite: A 2:1 type silicate clay usually formed from mica that has a high net negative charge

Verticulate: Whorled, with three or more members or parts attached at the same node of the supporting axis; in grasses, commonly used to describe the arrangement of branches in an inflorescence

Villous: Bearing long weak hairs

- - W - -

Warm-Season Grass: Grasses making the most of their growth in the late spring and summer under an optimum range of 30-40C, and full light saturation

- - X - -

Xylem: A complex vascular tissue through which most of the water and minerals of a plant are conducted

- - Y - -

- - Z - -

Zygote: The diploid (2n) cell resulting from the fusion of male and female gametes