Displaying 121 - 159 out of 159 Object(s)
| Term | Definition | |
|---|---|---|
| Primary leaflet | The first division of a compound leaf. |  |
| Primary rachis | The main rachis of a compound leaf or a compound inflorescence. | |
| Primary vein | See midrib. | |
| Primary venation | The largest (in diameter) vein (e.g., in camptodromous venaton) or veins (e.g., in actindodromous venaton) in a leaf blade. Same as midrib. |  |
| Prophyll | In monocots, the first leaf produced on a branch and located between the branch and the main axis; often two-keeled. |  |
| Pseudopetiole | The narrowed portion of the leaf located between the ligule(s) and the blade in many Bambuseae, in other Poaceae such as Pharus, and in some Cyperaceae. | |
| Ptyxis | Referring to the way a leaf is folded within a bud. | |
| Pulvinate | Possessing pulvini. |  |
| Pulvinulus (pl. = pulvinulus, adj. = pulvinate or pulvinulate) | An enlargement at the base of the petiole or petiolule of leaves. |  |
| Pulvinus (plural = pulvini) | An enlargement of a portion of the petiole, without an apparent function (e.g., Protium, Burseraceae) or sometimes controlling the orientation of the leaf or leaflet (e.g., Mimosa polydactyla and M. pudica, Fabaceae). | |
| Reticulate venation | Referring to the venation of a leaf which forms a network. |  |
| Secondary leaflet | The second division of a compound leaf. | |
| Secondary vein | A leaf vein arising from the midrib or primary vein. Same as lateral vein. |  |
| Secondary venation | The second order of venation in a leaf blade, i.e., the veins that arise from the midrib. | |
| Simple leaf | Referring to a leaf that is not divided into smaller units. Opposite of compound. |  |
| Spiral leaves | Referring to alternate leaves that are inserted in a spiral pattern around the twig. Compare with distichous leaves. | |
| Spongy mesophyll | Referring to loosely group, unorganizedof cells located located between the palisade mesophyll and the abaxial epidermis. Photosynthesis takes place in both palisade and spongy mesophyll. |  |
| Stipel (stipellate) | A small stipule at the base of leaflets and not at the base of the leaf as is the case with a true stipule, e.g., species of Andira; stipels are only found in compound leaves and a leaf that bears them is referred to as a stipellate leaf. |  |
| Stipulate | Possessing stipules. |  |
| Stipule | A reduced leaflike or bractlike appendage, either solitary or paired, inserted at the base of the petiole and variable in morphology. | |
| Stipule cap | In some Rubiaceae (e.g., Duroia), the structure formed by the fusion of the stipules; it covers the apical buds and usually falls off as soon as the bud develops. | |
| Stipule persistence | In the Rubiaceae, the persistency of the stipules provides a useful character for identifying genera and subgenera. Readily caducous stipules are present only when the leaves are in bud; caducous stipules are present during leaf development but fall before the leaves fall; and persistent stipules are still present after the leaves of their node fall. | |
| Stipule scar | Referring to the scars left on the stem after the stipules have fallen. Because many stipules are caducous, one has to look carefully for scars to determine if stipules were present at an earlier stage of development. |  |
| Terminal leaflet | In a pinnately compound leaf, the leaflet at the end of the rachis. Note that pinnately compound leaves with terminal leaflets are imparipinnate ( = odd pinnate). |  |
| Ternate leaves | In groupings of three; e.g., the ternately compound leaves of some species of Sapindaceae. | |
| Tertiary venation | The third degree or third smallest veins in a leaf blade, arising from the secondary veins. | |
| Trifoliolate | With three leaflets. |  |
| Tripinnately compound leaf | A compound leaf divided into three parts, each of which is pinnately compound. | |
| Triplivenation | With three ± equal, longitudinal veins departing from the base of a leaf blade. | |
| Unifacial | Referring to a leaf with the same type of tissue on each side as observed in a transverse section. | |
| Unifoliate | Referring to a plant with one leaf. | |
| Unifoliolate leaf | A leaf appearing to be simple but believed to be derived from an ancestor with a compound leaf, commonly found in species of Fabaceae. | |
| Vaginate | Possessing a sheath; e.g., used to describe the petiole base of some species of Piper. | |
| Variegated leaves | Having streaks, marks, or patches of different colors; e.g., the immature leaves of some species of Calathea (Marantaceae) and several species of Psychotria (Rubiaceae), and the mature leaves of Cyclopogon olivaceus (Orchidaceae). |  |
| Veinlet | See venule. | |
| Venule | The ultimate division of the venation of a leaf blade. |  |
| Vernation | The arrangement of leaves in the bud. | |
| Very widely ovate | Very widely ovate refers to a leaf, sepal, petal, or other flat structure that is wider at the base than at the midpoint, tapers toward the apex, and has a length-to-width ratio of 1:1 or less. |  |
| Whorled leaves | Arising from an axis in groups of more than two leaves at the same node; e.g., leaves along a stem or flowers along a rachis. Same as verticillate. Compare with alternate and opposite. |  |