From this midrib arise branches called veins. The veins, therefore, serve as a circu­latory system as well as like a skeleton of the leaf. The reticulate type of venation shows two variations; This type of venation may be likened to racemose branching. Ring in the new year with a Britannica Membership. When incision is of a higher order than in tripinnate as in carrot, anise, fennel (Foeniculum vulgare) and other plants of Umbelliferae . (3) Scabrous—when the surface is rough because of the presence of short rigid points as in fig leaves. (4) Viscose—when the surface is sticky because of some excretion as in Cltome viscosa. The pattern of leaf incision depends on the type of venation. The blade is the major photosynthetic surface of the plant and appears green and flattened in a plane perpendicular to the stem. 1. a thin plate or layer. In Macfadena unguiscati from Assam, the three terminal leaflets become claw-like hooks . (6) Tendrillar—when the apex forms a tendril for climbing as in Gloriosa. Such leaves contain a special storage tissue. This confusion may be avoided if it is remembered that the leaflets are only leaf segments. Venation follows certain basic patterns. Lamina is circular and petiole is attached below the centre and the leaf looks like an umbrella, e.g., lotus, Nelumbo nucifera (Fig. Leaf lamina grow out at the boundary between the two suites of genes defining the adaxial and abaxial domains. This is called perfoliate   and is found in Aloe perfoliata, Pladera perfoliata, Bupleurum, etc. Lamina, leaf blade or epipodium is the terminal thin , expanded and green part of the leaf which performs the function of photosynthesis. Typically, a leaf consists of a broad expanded blade (the lamina), attached to the plant stem by a stalklike petiole.In angiosperms leaves commonly have a pair of structures known as stipules, which are located on each side of the leaf base and may resemble scales, spines, glands, or … (3) Succulent—when soft and juicy as in Kalanchoe. (15) Cuneate or wedge-shaped as in Pistia stratiotes. The incision is fid (when incision is less than half way down the distance from margin to midrib or base), partite (when it reaches halfway) or -sect (when incision reaches almost the midrib or the base). Welcome to BiologyDiscussion! In this type the vascular supply, after reaching the base of the lamina, breaks up into a number of equally strong veins or costas. The leaf may be petiolate (with petiole) or sessile (without petiole). (5) Retroserrate—the teeth are pointed downwards. Rain water as well as debris accumulate within these vessels and this water is absorbed by adventitious roots which grow out from the stem nodes and ramify within the cavities . (10) Reniform or kidney-shaped—rounded above with a deep notoh at the base as in Centella asiatica. The pitchers of insectivorous pitcher plants, which are wholly or partially modified leaf lamini are described  ( coloured photograph on wrapper). Read More., Cyperaceae: Characteristic morphological features, Poaceae: Characteristic morphological features. This is another rare type found in the Paris plant (Paris quadrifolia ). It bears the weight of the lamina and conducts water and food materials between the stem and leaf. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. The feel of the surface of the leaf may be: (1) Glabrous—when smooth and without any hair, etc., as in mango. (4) Oblong—more or less rectangular as in banana (Musa sp.). Climbing hooks are sometimes modified leaves. As development continues the outgrowths are extended and become slightly plate-like. (6) Ovate or egg-shaped—as in china-rose and banyan. What are the characters Mendel selected for his experiments on pea plant? These spines may be comparatively small as on the leaves of Argemone mexicana, Pineapple, Agave, Aloe, etc. The edge of the leaf may be regular or irregular, may be smooth or bearing hair, bristles or spines. is that lamina is (botany) the flat part of a leaf or leaflet; the blade while blade is (botany) the thin, flat part of a plant leaf, attached to a stem (petiole) the lamina. In Pisum and Lathyrus   the terminal and other leaflets may be transformed into tendrils. (9) Bi-crenate—margin toothed and the teeth are again crenate. Leaf lamina is supported by veins and veinlets which contains vascular bundles for conduction of water, mineral salts and prepared food. Leaflets are borne in pairs as in Tamarindus indica , different species of Cassia, Swietenia mahogoni, etc. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? Disclaimer Copyright, Share Your Knowledge As liquid moves through the leaf lamina, from entry at the petiole–lamina junction to the sites of evaporation, its flow rate at a given water potential difference depends on the lamina hydraulic conductance (Klamina). Only a single leaflet is articulated to the top of the winged petiole. Leaflets (usually in pairs) are borne directly on rachis. See more at leaf. -nae (-ˌni) -nas. 26.5). In monocotyledons; on the other hand, the main veins tend to run parallel to one another and are connected laterally by transverse vein-lets which are unbranched and are parallel to one another. 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