a dry, 1-seeded fruit with a firm close-fitting outer coat that does not open by any regular dehiscence (the process of splitting open at maturity). All fruits (seeds) of the Smartweed and Composite Families are achenes. 
a description of the shape of a leaf tip whose sides are somewhat concave and appear stretched out to a protracted point .
placed singly at different heights on the stem or axis; any arrangement of leaves or other parts that are not strictly opposite or whorled.
a plant which completes its life cycle in one growing season. Compare with winter annual, biennial, perennial.
Annuel, elle d’hiver
(adj.) Se dit d’une plante qui germe à l’automne, passe en général l’hiver au stade de rosette, fleurit et fructifie au printemps suivant et meurt au cours de l’été.
the enlarged outer portion of the stamen that produces pollen.
an appendage near the lower part of a leaf blade or petal; it may be pointed or rounded and shaped like the lobe of a human ear.
a bristle-like part or appendage, usually needle-shaped
the upper angle formed by the junction of a leaf or branch with the stem.
Offset a short side shoot arising at the base of a stem or from a root crown.
a plant which germinates in the spring, producing a rosette of leaves and remaining vegetative during the first summer; overwinters as a rosette; bolts (sends up a flowering stalk) during the second summer; sets seed; and dies at the end of the second growing season. Compare with annual, winter annual, perennial.
Biological Control
Involves establishing a self-perpetuating population of a natural enemy from elsewhere with the intent of providing sustained weed suppression. It is particularly applicable to introduced weeds that have formed stable populations on uncultivated land. It relies on the agent, which usually an insect, increasing to suppress increases in the weed population. The control is slow to take effect, up to 20 years, but in the right situation it is the most cost effective and environmentally friendly means of weed control.
Biopesticides are pesticides derived from natural materials such as animals, plants, bacteria, and certain minerals. Acetic acid (Vinegar) and corn gluten meal are examples of two biopesticides that suppress or control certain weed species.
the expanded part of a leaf or petal.
in this site, it is used only in the sense of a fine, powdery coating on leaves, stems, etc. Also see glaucous. (When referring to a flower, the word blossom is used.)
a flower.
a leaf that is much reduced; particularly the small or scale-like leaves immediately below each flower in a flower cluster, or associated with the inflorescence.
the sepals of a flower; the outermost series of flower parts; it is usually, but not always, green and leaf-like in texture.
fringed with fine hairs along the edge or margin.
partly or wholly surrounding the stem.
divided to or almost to the midrib, as a palmately cleft leaf or pinnately cleft leaf.
the junction between leaf blade and leaf sheath in grass and sedge leaves.
made up of two or more similar parts, united into one whole. A compound leaf is divided into several separate leaflets. A compound unbel is made up of several simple umbels.
the petals of a flower; an inner series of flower parts, usually between sepals and stamens; it is usually white or coloured, and usually not leaf-like in texture.
a seed leaf. These tiny leaves are present in the embryo in the seed. In most broad-leaved dicotyledonous plants, they emerge when the seed germinates. They are the first green leaves of these seedlings and are always an opposite pair.
the part of the stem at the surface of the ground. Also, specialized appendages on the corolla in a flower as the hoods and horns in Milkweed, or the trumpet in the cultivated daffodil.
the stem of grasses and bamboos, usually hollow except at the swollen nodes.
a specialized cup-like structure that encloses one or more tiny flowers in the Spurge Family.
an inflorescence in which virtually every stem and branch ends in a flower, and does not have a well-defined central axis. The central or uppermost flower usually blossoms first.
with sharp teeth that are perpendicular to the margin; the two sides of each tooth being of about equal length and having the same slope.
with 2n (2 complete sets of) chromosomes per cell; one complete set having come from each parent.
floret a tubula flower in the central part of the flower head of many members of the Composite Family, as distinguished from a ray floret.
separated to very near the base.
with a continuous margin, not in any way toothed or otherwise indented or divided.
Environmental Impact Quotient (EIQ)
The EIQ is designed to provide growers and other decision makers with one number that indicates the magnitude of relative risk. The EIQ was developed by Kovach and others from Ohio State University to estimate the risk to farm workers, consumers, and the environment of pesticide active ingredients. The toxicology, as well as persistence and movement in the environment were used to calculate the EIQ. In the environmental impact of a pesticide product is determined by multiplying the application dose (kg ai/ha) by the EIQ value for the active ingredient. Thus, a higher environmental impact value indicates a greater risk compared to another product. By using lower herbicide rates and/or safer products, the environmental impact of weed control may be reduced.
the stalk of the stamen.
a small flower, especially the individual flowers in a flower head of the Composite Family; or the flower plus its two enclosing bracts, the lemma and palea, in the Grass Family.
the leaf blade of a fern, whether single or much divided.
a mature ovary with or without associated parts. In the botanical sense, it is not restricted to something sweet and juicy but includes all kinds of berries, dry seedpods , spiny burs, and single-seeded achenes.
covered with a powdery whitish substance or bloom that is easily rubbed off.
the absorbing organs (often root-like) of parasitic plants.
the floral cup or tube in a flower to which are attached the sepals, petals and stamens.
the flowering portion of a plant.
the part of a stem or rhizome between any two nodes.
one or more whorls of small leaves or bracts immediately underneath a flower, flower cluster or umbel, or surrounding a flower head.
lance-shaped; much longer than broad, and narrowed or pointed toward the tip
Leaf Axil
the upper angle between the stalk or blade of a leaf and the stem.
Leaf Sheath
the basal portion of a leaf that surrounds the stem, especially in grasses and sedges; the portion of a leaf between the stem node and leaf collar.
one part of a compound leaf.
a flat membrane or band of hair arising from the inner surface of the leaf sheath at its junction with the leaf blade.
the main or central rib or large vein of a leaf or leaf-like part; appears to be a continuation of the petiole.
the joint of a stem or rhizome; that portion of a stem to which the leaf is attached, and at which axillary buds and branches are produced.
a membranous or somewhat leaf-like tube surrounding the stem above each node in the Buckwheat or Smartweed Family. 
placed two at a node; on opposing sides of a stem, immediately across from each other.
the lower part of the pistil; it contains the ovules that later become the seeds.
the tiny structure inside an ovary that develops into a seed after fertilization.
the arrangement of leaflets, or of lobes, divisions, ribs or veins in a leaf or petal in which all of these units arise from almost the same point, as fingers from the palm of a hand.
a type of inflorescence that usually has a central axis and many branches that are them-selves more or less rebranched. 
the specialized calyx of members of the Composite Family; may consist of hairs, plumes, bristles or scales.
cut or cleft, but not quite to the midrib or base.
stalk of a single flower or of one flower in a cluster.
the stalk of a cluster of flowers, or of a flower head.
a plant that lives through three or more growing seasons. Compare with annual, winter annual, biennial.
a collective term for the calyx (sepals) plus corolla (petals).
stalk of one leaf.
the arrangement of leaflets, or of lobes, divisions or veins in a leaf or petal in which these units are arranged on each side of an elongated, central axis.
the female part of a flower, consisting of stigma, style and ovary; it contains the ovules and develops into the fruit which contains the seeds.
having one or more pistils but no stamens; female.
Power Ranking
Every weed species within the database contains a power ranking. The power ranking considers two components, how abundant and how difficult the species is to control in corn and soybeans. These initial rankings have originated from informal grower and crop advisor surveys whereby they where asked to prioritize a number of weed species in terms of management importance. In the future more formal surveys, along with feedback through will determine power rankings for weeds on a yearly basis.
an inflorescence composed of several to many flowers, and later fruits or seedpods, each with a distinct pedicel, arranged along a central axis which continues to elongate throughout the flowering period. The lower flower blossoms first.
the central axis of a spikelet, particularly in the grasses and sedges; the axis to which the florets are attached.
the central axis of either a pinnate leaf or of an inflorescence.
Radical Leaf
a leaf that arises from an underground stem (rhizome) and whose petiole emerges directly from the soil surface.
one of several branches of an umbel or similar inflorescence
Ray Floret
the outer florets in the flower head of some members of the Composite Family, as distinguished from a disk floret.
an underground stem, usually horizontal.
a circular cluster, with the parts spreading outward like spokes of a wheel.
one of the separate parts of a calyx; usually the outermost part of a flower, and usually (but not always) green.
a membranous partition.
with sharp teeth that point forward along the margin; one side of each tooth being longer than the other.
without a stalk; said of a leaf in which the leaf blade has no petiole but is attached directly to the stem, or of a flower that has virtually no pedicel but appears to be attached directly to the stem.
the relatively short fruit of certain members of the Mustard Family, usually not more than twice as long as wide.
the relatively long fruit of certain members of the Mustard Family, usually at least four times longer than wide.
a distinct space between two lobes, as on a leaf blade .
a large bract enclosing an inflorescence, at least when young; may be papery in texture and white or brownish more leaf-like and green, white or highly coloured, as in the woodland wild flower, Jack-in-the-pulpit.
an inflorescence with sessile flowers, and later fruits, arranged along a central axis. The lower flowers blossom first.
the basic unit of a grass or sedge inflorescence. It contains the flower(s) and seed(s) that are enclosed by the chaffÕ (by the lemma, palea and glumes).
the stem or supporting structure of any organ, as the petiole of a leaf, the peduncle of an inflorescence, the pedicel of a flower, or the filament of a stamen.
the male or pollen-bearing part of a flower, consisting of an anther and a filament.
having stamens but not pistils; male.
the part of the pistil that receives the pollen; usually the uppermost or outermost part of a pistil.
the stalk of a pistil, between the bottom of the pistil and the top of the receptacle (found inside the flower); not to be confused with the pedicel that occurs below the receptacle to which the petals and sepals are usually attached.
having stipules.
an appendage at the junction of the leaf petiole and stem; usually occur in pairs, one on each side of the petiole, and may be attached to the petiole or to the node of the stem.
a horizontal stem at or slightly below the surface of the ground, and gives rise to a new plant at its tip.
the more or less elongated part of the pistil between the ovary and the stigma.
juicy or fleshy, often brittle.
the primary root; usually larger than the branch roots; and usually present in most annual and biennial plants.
the slender, twining or clasping structure at the ends of some compound leaves or coming directly from the stem.
with 4n (4 complete sets of) chromosomes per cell.
a thickened, short underground stem or root serving as a storage organ containing reserve food. The common potato that we eat is a tuber.
a spherical, rounded or flat-topped inflorescence with the pedicels of the individual flowers, or the peduncles of the umbellets, arising from approximately the same point.
a secondary umbel within a compound umbel.
of one sex; having only stamens or only one or more pistils in each flower.
three or more leaves or flowers at one node; with the parts encircling the stem and pointing outward like the spokes of a wheel.
Winter Annual
a plant that germinates in the fall; usually overwinters in the rosette stage; flowers and sets seed the following spring; and dies in the summer.