| Internode |
The section of the stem between the nodes. Plants can vary the intermodal length in response to amounts of sun or shade. In deep shade, internodes are lengthened. |
| Interpetiolar stipules |
Stipules situated between the two petioles of opposite leaves. This form is characteristic of stipules in many Rubiaceae species. See Intrapetiolar stipules. |
| Involucre |
A ring or whorl of small leaves, or bracts, at the base of a flower, flower cluster, or fruit. In Euphorbiaceae the involucre is the cuplike structure that holds the nectar glands, nectar, and head of flowers, and sits above the bract-like cyathophyll structure. |
| Involute |
Relating to a leaf, the margins rolled upwards, towards the adaxial, or upper leaf surface. See revolute. |
| Jugate |
Describes a structure of paired items joined together, such as opposite leaflets on a rachis. The word comes from the Latin, jugatus, meaning joined. |
| Lamina |
Leaf blade. |
| Lanceolate |
Narrowly lance-shaped, and being widest about one third from base and pointed at both ends. Oblanceolate, is widest about two-thirds up from the base. |
| Lateral vein |
Secondary vein, or the first level of branching off the midrib. |
| Latex |
A fluid that is released from a damaged point of a plant. Latex may be milky-white, as in Euphorbia or Ficus species. |
| Lax |
Loose from one another, and possibly drooping. |
| Leaf |
A leaf is a plant's principal organ of photosynthesis, and it is an outgrowth of the stem. |
| Leaf axil |
The upper angle between a leaf and its supporting stem. |
| Leaflet |
One portion or part of the blade of a compound leaf. |
| Legume |
A dry fruit, that is a pod, formed from one carpel, and is either dehiscent along both sides, or indehiscent. Legumes are characteristic of the Fabaceae, Mimosaceae and Caesalpiniaceae families. |
| Lenticel |
A pore in the outer layer of a woody stem through which an interchange of gases takes place. The plant loses water through its lenticels. |
| Lenticellate |
With lenticels. Refer to lenticel. |
| Lepidote |
With small scales across the surface. |
| Liana |
A climbing plant, such as forest vines, with long woody stems that use other plants to gain height while rooted in the ground. See scandent. |
| Liane |
A climbing plant, such as forest vines, with long woody stems that use other plants to gain height while rooted in the ground. The alternative term is liana. See scandent. |
| Lignin |
Lignin is a plant substance that is durable and tough, and forms into vital structural materials to support plant tissues. Lignins are deposited in cell walls, providing rigidity, particularly in wood and bark. |
| Linear |
When referring to a leaf share, very narrow, with length more than 5 times the width, and the sides parallel. |
| Lithophyte |
A plant with germinates and grows on rocks. Several fig species are lithophytes, with their roots then locating and rooting in soil. |
| Lithophytic |
A plant with germinates and grows on rocks. Several fig species are lithophytes, with their roots then locating and rooting in soil. |
| Lobe |
A corolla tube that is continuous at the base may open into petal-like segments, called lobes. |
| Lobed |
When referring to a leaf share, with several points and deeply indented margins. |
| Locule |
A cavity in the carpel that houses the ovule or ovules. |
| Loment |
Pods flattened between each seed, and splitting along the flattened sections into individual sections between the seeds. |
| Lomentum |
Pods flattened between each seed, and splitting along the flattened sections into individual sections between the seeds. |
| Margin |
The outer edge of the leaf. |
| Mealy |
Covered with particles that resemble flour. |
