| Inferior ovary | An ovary situated below the origin of sepals and petals. In many species the ovary is below the point of attachment of all the other parts of the flower, i.e., embedded in the flower stem. It usually shows as a swelling below the flower and may be seen only by cutting through this swelling. |
| Inflorescence | A group of flowers and associated plant parts. |
| Infructescence | A group of fruits and associated parts arising from an inflorescence. An inflorescence with mature or maturing fruit. |
| Internode | The part of the stem between leaves or branches. |
| Involucel | A bract or bracts subtending an individual flower in a compound inflorescence. |
| Involucre | A whorl of distinct or united leaves or bracts beneath a flower or cluster of flowers commonly found especially on species in Asteraceae but also in Apiaceae, Dipsacaceae and Polygonaceae. Also a bract or bract pair subtending the inflorescence of some members of Betulaceae, especially Carpinus and Corylus. |
| Irregular flower | A flower unequal in the size, form, or union of its similar parts; zygomorphic or bilaterally symmetrical. Example: Fabaceae (Legume Family). |
| IUCN | International Union for Conservation of Nature. |
| L48(I) | Introduced to the continental United States |
| L48(N) | Native to the continental United States |
| L48(NI) | Native and Introduced to the continental United States |
| Laciniate | Fringed or having edges irregularly and finely slashed. |
| Lanceolate | Having the shape of a spear-head or lance. |
| Leafless | Without leaves. |
| Leaflet | A division or part of a compound leaf. |
| Legume | Any of a large group of plants in the pea family (Fabaceae). |
| Lenticel | A corky pore in young bark. |
| Lobe | Part or segment of a flower or leaf; a deep indentation that does not break the continuity of the structure. |
| Lobed flower | A tubular or funnel shaped flower that opens into petal like lobes. |
| Lobed leaf | A leaf with indentations not more than halfway to the midrib, with the tips of the segments rounded. |
| Lyrate | A pinnately divided leaf with an enlarged terminal lobe. |
| MB | Manitoba |
| Midrib | The main or central rib or vein of a leaf. |
| Monoecious | A plant or plant species producing male and female reproductive structures on the same plant but on separate flowers. |
| Mucronate | Leaf apex with short spiny tip. |
| Native | A plant that lives or grows naturally in a particular region without direct or indirect human intervention. |
| NB | New Brunswick |
| Nectar | A sweet fluid produced in flowers. |
| Needle | The long and narrow leaf of pines and related species. |
| NL | Newfoundland and Labrador |
| Node | The place on a stem where leaves or branches normally originate; a swollen or knoblike structure. |
| NS | Nova Scotia |
| NT | Northwest Territories |
| NU | Nunavut |
| Nut | A dry fruit with one seed and a thick hard wall. |
| Obcordate | Inversely cordate, heart-shaped with petiole attached to point. |
| Oblanceolate | Inversely lanceolate with top wider than bottom. |
| Oblique | Leaf shows asymmetry at the base. |
| Oblong | Much longer than broad with sides nearly parallel. |
| Obovate | Inversely ovate, with the narrower end of the leaf blade toward the branch. |
| Obtuse | Blunt or rounded at the tip. |
| ON | Ontario |
| Opposite | Said of leaves originating in pairs at a node, with the members of each pair opposite each other on the stem. |
| Orbicular | Circular or nearly so. |
| Oval | Having the general form, shape, or outline of an egg; egg-shaped. |
| Ovary | The basal part of the pistil, bearing the ovules, which later develop into seeds. See also Inferior ovary; Superior ovary. |
| Ovate | Shaped like an egg, with the narrow end at the apex. |
| Palmate | Divided or radiating from one point, resembling a hand with the fingers spread. Leaves may be palmately compound and/or palmately lobed; they may also have palmate venation. |
| Palmately compound | Leaflets radiating from one point, resembling a hand with the fingers spread. Leaves may also be palmately lobed or have palmate venation. |
| Panicle | A branched raceme; a raceme of racemes. |
| Pappus | The calyx modifications found on many species of Asteraceae (Sunflower Family), commonly appearing as hairs, bristles, or scales, and usually persisting on the fruit. |
| Parallel | A leaf whose veins run in parallel from the stem. |
| Parallel venation | Main veins running from base to apex of leaf. |
| Part Shade | Part shade is classified as a garden receiving 4-6 hours of sun with dappled shade from trees or as approximately 4 hours of sun with shade either in the morning or afternoon. Part shade and part sun are used interchangeably by the horticulture industry. |
| PE | Prince Edward Island |
| Pedicel | The stalk of a single flower in a cluster of flowers. |
| Peduncle | The stalk of a solitary flower or of a cluster of flowers. |
| Peltate | Leaf shape that is round or rounded with the petiole attachment on the abaxial leaf surface and not on a leaf edge. |
| Pendulous | Suspended, hanging. |
| Perennial | A plant or plant species with a normal life cycle exceeding two years. |
| Perfect | A flower with both male and female reproductive organs; bisexual, hermaphroditic or monoclinous. |
| Perfoliate | A leaf with the base united around the stem. |
| Perianth | Collective term for petals and sepals (corolla and calyx). |
| Petal | Unit of the corolla. |
| Petiole | A leaf stem. |
| Petiolule | The stalk of the leaflet of a compound leaf. |
| Phyllary | A term sometimes used for individual bracts below the head of flowers in Asteraceae (Sunflower Family), so designated to avoid confusion with bracts on the flower stem. |
| Pinnae | (Pinna, sing.) A division of a pinnately compound leaf. |
| Pinnate | Arranged along an axis. Leaves may be pinnately compound (see below) and/or pinnately lobed; they may also have pinnate venation, with veins extending from the midrib. |
| Pinnately Compound | Leaves with leaflets opposite each other on each side of the midrib. They may be oddly pinnate, ending with a leaflet at the tip, or evenly pinnate, with no leaflet at the end. These leaflets may be twice compound (Bipinnate), like the leaves on sensitive briars (Mimosa spp.). |
| Pistil | The seed-producing or female organ, consisting of ovary, style, and stigma; usually located in the center of the flower. |
| Pistillate flower | A flower with pistils, but no stamens. |
| Pith | The spongy tissue in the center of a stem. |
| Pod | A dry fruit that splits after ripening, a term applied to fruits in the Legume Family. |
| PR(I) | Introduced to Puerto Rico |
| PR(N) | Native to Puerto Rico |
| PR(NI) | Native and Introduced to Puerto Rico |
| Prickle | A sharp process on the surface of a twig or leaf, an outgrowth. |
| Prostrate | Lying flat on the ground. |
| Provides Nesting Materials/Structure for Native Bees | A plant that native bees nest beneath, within, or harvest parts from to construct their nests. |
| Proximal | Toward the base of a plant or the point of attachment of a plant part. Cf, Distal. |
| Pubescent | Said of stems or leaves with soft hairs. |
| QC | Quebec |
| Quadrifidus | Divided into four parts. |
| Raceme | An inflorescence in which each flower is attached to the main stalk by a short stem (pedicel). The youngest flowers, at the tip, may continue to develop while those below are forming fruit. |
| Rachis | The axis of a pinnately compound leaf. |
| Radial asymmetry | The flower can be cut into two equal halves in many ways, provided that the plane of cutting passes through the center. |
| Ray | The outer irregular flowers in the heads of many Compositae (Sunflower Family). Each has a single, tongue-shaped corolla. |
| Receptacle | End of stem to which flowers are attached. lFig. 1) |
| Regular flower | A flower equal in size, form, and union of its similar parts; radially symmetrical. Example: Solanaceae (Potato Family). |
| Reniform | Kidney-shaped. |
| Retuse | Having a rounded apex with a central depression. |
| Rhizobia | Soil-borne bacteria which form nitrogen-rich root nodules. |
| Rhizobium | Soil-borne bacteria which form nitrogen-rich root nodules. |
| Rhizome | A horizontal underground stem. |
| Rib (of cactus) | A ridge; a raised surface running vertically or sometimes spiraling, and bearing areoles in a row along its summit. Often thought of as being composed of more or less united tubercles which may be evident as bulging masses along it. |
| Rosette | An arrangement of leaves radiating from the stem at a nearly common level, frequently at or just above the ground line. |
| Runcinate | Leaf having incised margins with the lobes or teeth curved toward the base. |
| Sagittate | Shaped like an arrowhead. |
| Samara | A dry, winged, one-seeded fruit. |
| Sap | Watery fluid that circulates through a plant carrying sugars, minerals and nutrients. |
| Scabrous | Rough to the touch. |
| Scape | A naked flower stem rising from the ground. |
| Scorpioid | Curled, like the tail of a scorpion. |
| Semi-evergreen | Having foliage during part of the winter or dry season or tending to be evergreen in a mild climate but deciduous in a rigorous climate. |
| Sepals | Parts that surround the petals, stamens, and pistil; usually green and leaflike. Sometimes they are the same size, shape, and color as the petals; as in Cooperia pedunculata (rain lily), in which case both sepals and petals are called sepals. |
| Serrate | Toothed like a saw. |
| Sessile | Lacking a stalk of any kind: a flower without a pedicel or a leaf without a petiole. |
| Shoot | A stem or branch and its leaves. |
| Shrub | A low growing, usually less than 15 feet, woody perennial plant without a central stem. |
| Simple | Not divided into parts, e.g., a leaf with the blade in one piece. |
| Sinus | The depression or recess between two lobes. |
| SK | Saskatchewan |
| Solitary | Borne singly; alone. |
| Spatulate | Paddle, or spoon shaped, broad at the tip and narrowed towards the base. |
| Special Value to Native Bees | Recognized by pollination ecologists as attracting large numbers of native bees. |
| Special Value to Bumble Bees | Recognized by pollination ecologists as attracting large numbers of bumble bees. |
| Special Value to Honey Bees | Identified by beekeepers and pollination biologists as an important pollen or nectar source (honey plant) for honey bees. |
| Spike | Flowers are attached directly to the main stem; no pedicels are present. The youngest flowers or buds are at the top. Spp. Abbreviation for plural of "species." |
| Spine | A sharp-pointed structure commonly related to a leaf in origin. |
| Spur | A tubular or saclike extension of a sepal or petal, usually containing nectar. |
| Stamens | The male parts of the flower, carrying the pollen. usually in the center of the blossom and surrounding the pistil, if present. Filaments and anthers collectively. |
| Staminate | Having stamens. |
| Staminate flower | A flower with stamens but no pistil. |
| Stellate | Star shaped, said of certain branched hairs. |
| Stem | The main axis of a plant. |
| Stigma | The tip of the pistil, which receives the pollen; may be rounded, lobed, or branched |
| Stipule | A basal appendage of the petiole; usually in pairs. Varies in shape and may be minute and hairlike or stiff and sharp, or like segments of the leaf blade. |
| Stipules | Leaflike structures that grow where the leaf is attached to the stem. |
| Stolon | A horizontal above ground stem. |
| Style | The stalk-like part of the pistil, connecting the ovary and the stigma. |
| Subshrub | Shorter than a shrub, often weakly woody and persisting for only a few years. |
| Superior ovary | An ovary situated above the origin of sepals and petals. |
| Supports Conservation Biological Control | A plant that attracts predatory or parasitoid insects that prey upon pest insects. |
| Tap | The main, central root of a plant. |
| Taproot | A single main root that grows vertically into the ground. |
| Tendril | A slender coiling or twining structure modified from a leaf, branch, or other organ. |
| Tepals | Collective term for sepals and petals when sepals are petal-like, as in Cooperia pedunculata (rain lily). |
| Thorn | A sharp-pointed structure formed by a modified branch. |
| Toothed | Said of petals or leaves having margins more or less sharply indented. |
| Tree | A woody perennial plant having a single main stem or trunk which generally grows more than 20 feet tall. |
| Trifoliate | Having three leaflets. |
| Tripinnate | A bipinnate leaf whose pinnae are divided into a third set of leaflets. |
| Truncate | Ending abruptly, e.g., a leaf blade squared at the base. |