Displaying 81 - 120 out of 159 Object(s)
| Term | Definition | |
|---|---|---|
| Leaf venation mixed craspedodromous | Referring to a type of leaf venation in which some of the secondary veins terminate at the leaf margins and the remainder of the secondary veins do not, e.g. half of the secondary veins are craspedodromous and the other half camptodromous. |  |
| Leaf venation perfect acrodromous | Referring to a type of leaf venation in which two or more primary or strongly developed secondary veins arch upward from the base or above the base and converge near the apex. Based on Hickey, 1973. For more information about leaf venation see Ellis et al, 2009. |  |
| Leaf venation simple craspedodromous | Referring to a type of leaf venation in which all of the secondary veins terminate at the leaf margins. |  |
| Leaf venation suprabasal acrodromous | Referring to a type of leaf venation in which two or more primary or strongly developed secondary veins arch upward from above the base. Based on Hickey, 1973. For more information about leaf venation see Ellis et al, 2009. | |
| Leaf venation suprabasal actinodromous | Referring to a type of leaf venation in which three or more primary veins diverge radially from a single point above the point of attachment of the petiole. |  |
| Leaflet | A division of a compound leaf. |  |
| Leaflets alternate | Leaflets not placed along the rachis of a pinnately compound leaf directly opposite one another. |  |
| Leaflets opposite | Referring to leaflets placed along the rachis directly opposite of one another. | |
| Leafstalk | In legumes, the main axis of the leaf from its attachment to its apex; i.e., the petiole plus the rachis. | |
| Lepanthiform | Referring to tubular sheaths of leaves in the Orchidaceae that are flared and usually ciliate at the apex. | |
| Lepidopylls | Scalelike leaves found at the apical meristems of stems and rhizomes of Gunneraceae. | |
| Marginal leaf vein | A leaf vein that runs more-or-less parallel to the margin of a leaf. |  |
| Megaphyll | A leaf with more than one vein; characteristic of ferns, gymnosperms, and flowering plants. See microphyll. | |
| Megasporophyll | A leaf bearing a megasporangium. | |
| Microphyll | A leaf with a single vein, characteristic of Lycopodiaceae and Selaginellaceae and not found in the flowering plants. Compare with megaphyll. | |
| Microsporophyll | A reduced leaf bearing one or more microsporangia. | |
| Midnerve | Same as midrib but used less frequently. |  |
| Midrib | The primary vein of a leaf, bract, sepal, or petal. Same as costa, midnerve, midvein, and primary vein. | |
| Midvein | Same as midrib but used less frequently. | |
| Narrowly obovate | Narrowly obovate refers to a leaf, sepal, petal, or other flat structure that is wider above the midpoint and has a length-to-width ratio of 2:1 to less than 3:1. |  |
| Narrowly ovate | Narrowly 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 2:1 to less than 3:1. |  |
| Odd-pinnate leaf | Pinnate with an odd number of leaflets; i.e., without a terminal leaflet. Same as imparipinnate. |  |
| Opposite leaves | Reffering to leaves that arise from an axis in pairs at the same node. Compare with alternate and whorled. |  |
| Palinactinodromous | Referring to a type of leaf venation in which the primaries have one or more subsidiary points of radiation above the lowest point. |  |
| Palisade mesophyll | Referring to one or more layers of cells located directly under the epidermal cells of the adaxial leaf blade surface. The palisade mesophyll is oriented vertically and is longer than broad. Photosynthesis takes place in both palisade and spongy mesophyll. |  |
| Palmately veined | Referring to leaf venation in which the main veins of the blade radiate from a common point near the base. |  |
| Parallel venation | Generally applied to secondary or higher-order veins that are parallel to each other and to the margins of the leaf, sepal, or petal in which they occur but in monocots they are often numerous primary veins of the same size. |  |
| Paripinnate leaf | Pinnate with an even number of leaflets; i.e., without a terminal leaflet. Same as even-pinnate and parapinnate.. |  |
| Peltate leaf | Referring to a leaf blade attached to the petiole by its lower surface rather than its margin; for example species of Nymphaea glandulifera, Hydrocotyle umbellata, and those illustrated for this term. |  |
| Percurrent veins | Veins of the same order that run parallel to each another between veins of a higher order; e.g., tertiary veins and their orientation between secondary veins. |  |
| Perfoliate | Referring to a stem that penetrates two leaf bases that are completely fused together. When two leaf bases wrap around the stem the leaf is said to be amplexicaulous or clasping. |  |
| Petiole | The stalk of a leaf; in compound leaves, the stalk between the leaf attachment on the stem and the insertion of the first leaflet. | |
| Petiolule | The stalk of a leaflet. Several different orders of petiolules may exist in leaves twice or more compound; those in a palmately compound leaf radiate from a common central point. | |
| Phyllotaxy | Three-dimensional arrangement of leaves on a stem. | |
| Pinna (plural = pinnae) | The primary division of a compound leaf, especially of ferns. | |
| Pinnate (pinnately compound leaves) | Bearing leaflets along a common axis or rachis. See paripinnate and imparipinnate. | |
| Pinnate venation | A type of venation pattern in which the secondary veins run parallel to each other from the midrib toward the margin. |  |
| Pinnately veined | Bearing the secondary veins along both sides and for the length of the midrib (primary vein). | |
| Pliveined (plinerved) | Referring to leaf blade venation in which the midvein is accompanied by several nearly equal secondary veins arising at or near the base; e.g., in many Ericaceae and some Euphorbiaceae. |  |
| Posterior rib | In Araceae, the connate or apparently united portion of the basal veins (those primary veins that join the midrib at the petiole attachment). |