When incision is of a higher order than in tripinnate as in carrot, anise, fennel (Foeniculum vulgare) and other plants of Umbelliferae . lam•i•na. Privacy Policy3. Lobes: The rounded portion of the leaf margin. (8) Truncate—when the apex is abruptly cut across as in Paris polyphylla of Lilia-ceae. A few monocotyledons like some aroids, Smilax, Dioscorea, etc., how­ever, show reticulate venation. Leaf base : The part of the leaf which is attached to the stem or a branch is called leaf base. Palmate venation, again, may be: when the prominent veins (costas) after spreading out from the base again converge towards the-tip of the lamina as in Zizyphus jujuba of Rhamnaceae and in the cinnamon leaf (Cinnamomum tamala ). In a simple leaf the lamina, however dissected, will present a single appearance because of the presence of some sort of laminar connection between the dissected lobes. Such leaves contain a special storage tissue. The base of a leaf is the lower part of the lamina, where it is attached to the petiole or stem. Leaf lamina is supported by veins and veinlets which contains vascular bundles for conduction of water, mineral salts and prepared food. Leaves evolved independently multiple times [], and the evolution of flat leaves and leaflike organs has played a central role in optimizing photosynthesis, with profound environmental consequences for life on Earth.Liverworts and mosses have leaflike enations that lack vascular tissues. (6) Gland-dotted—when glands are found on the leaf surface as in lemons. This is found in Balanites aegyptiaca of Simarubaceae, Hardwickia binnata of Papilionaceae, Campsis grandiflora of Bignoniaceae, etc. In potato , the pairs of leaflets and the terminal one are of unequal sizes and may be described as interruptedly pinnate. The leaf apex becomes a tendril in Gloriosa superba. [1650–60; < Latin lāmina] (7) Cirrhose—when the mucronate-like apex ends in a fine thread-like structure as in banana. (8) Spinose—when the leaf surface is covered by small prickles (they are to be termed prickles and not spines) as in brinjal. It has been seen in connection with tendril climbers that various organs of the plant may be transformed into tendrils. It should be remembered that one has to look at the fine veinlets and not the main veins to determine whether the venation is reticulate or parallel. The secondary veins often do not reach the margin but before reaching the edge either fizzle out or curve and run parallel to the margin for a short length. 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 leaflike structures. It’s generally broad and flat. This is known as parallel or striate venation. Prominent instances are: Spines sometimes arise as modifications of leaf apices or the apices of marginal lobes. The very common Pteridophyte Marsilea quadri-foliata presents a quadrifoliate appearance  although the actual morphology of the four leaflets is not so simple. (8) Sagittate—shaped like an arrowhead with the two basal lobes pointing to­wards the base as in Sagittaria sagittifolia and in arum. From this midrib arise branches called veins. (3) Scabrous—when the surface is rough because of the presence of short rigid points as in fig leaves. A leaf (plural leaves) is the principal lateral appendage of the vascular plant stem, usually borne above ground and specialized for photosynthesis.The leaves and stem together form the shoot. Venation follows certain basic patterns. Disclaimer Copyright, Share Your Knowledge The leaf blade: It is also called the lamina. Among the pinnately incised types some leaves, like those of radish or mustard, show lobes which are irregularly incised. Structurally, this means that the point of leaf…. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments. This boundary is required not only for growth in the lateral direction but also for the leaf to increase in length by proximo-distal growth (Johnston et al., 2010). (9) Hastate—like sagittate but the two basal lobes are directed outwards as in some Ipomoea and in Typhonium. Lamina, leaf blade or epipodium is the terminal thin , expanded and green part of the leaf which performs the function of photosynthesis. Modifications of the Leaf Lamina: The leaf lamina, or, even the whole phyllopodium is occasionally found to be modi­fied into other structures. These spines may be comparatively small as on the leaves of Argemone mexicana, Pineapple, Agave, Aloe, etc. Content Guidelines 2. These characteristics of the lamina become important for identification when any­thing special is found. The edge of the leaf may be regular or irregular, may be smooth or bearing hair, bristles or spines. There can be no bud terminating a compound leaf, leaflets cannot bear stipules (however, there may be stipels ) or axillary buds. The shape, margin, apex, surface, and extent of incision of lamina varies in different leaves. Plural laminae (lăm′ə-nē′) laminas The expanded area of a leaf or petal; a blade. Ring in the new year with a Britannica Membership. See more at leaf. (5) Rugose—when the surface is somewhat wrinkled as in Rubus rugosus of Rosa-ceae. Shoeing a number of strong veins (costas) which are. eppo.org. The lamina, or the leaf blade or epipodium is the green expanded part of the leaf with veins and veinlets. Results: The device indirectly estimates leaf moisture content using two electrodes applied to the leaf lamina of fresh and stored samples. In Macfadena unguiscati from Assam, the three terminal leaflets become claw-like hooks . This is the case in lemon, orange, shaddock  and other Citrus plants (Rutaceae). Each leaf typically has a leaf blade called the lamina, which is also the widest part of the leaf.Some leaves are attached to the plant stem by a petiole.Leaves that do not have a petiole and are directly attached to the plant stem are called sessile leaves. 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 … Leaf Evolution. (3) Succulent—when soft and juicy as in Kalanchoe. https://www.britannica.com/science/lamina-plant-leaf, Cyperaceae: Characteristic morphological features, Poaceae: Characteristic morphological features. A compound leaf, just like venation, may be pinnate or palmate. (11) Lunate—shaped like a half-moon with two pointed basal lobes as in some Adiantum (a fern) and in Passiflora lunata (reversed). (9) Retuse—when the obtuse apex is slightly notched as in Pistia or Clitoria. It is known as pulvinus eg. The compound leaf again may be pinnate  or palmate. 2.62R) of Nymphaeaceae etc. (1) Entire—when the margin is smooth as in mango. How is the air cleaned before it enters the alveoli? (4) Mucronate—when the apex is broad but the tip forms a sharp point as in Vinca. (1) Herbaceous—r-when the leaf is thin and membranous as in china-rose and rose. The articulation shows that the leaf is not a simple one but compound. Such specialities are to be described in such cases. Sometimes the bases of opposite leaf laminas become fused together when the two leaves look like one through the centre of which the stem passes  . (ˈlæm ə nə) n., pl. Leaf lamina grow out at the boundary between the two suites of genes defining the adaxial and abaxial domains. (7) Cordate or heart-shaped –with a deep notch at the base as in betel vine (Piper betle). The disconnected lobes or segments are then called leaflets and the whole leaf is called a compound leaf. lamina definition: 1. a layer or thin sheet of tissue 2. one of two curved parts at the back of a vertebra (= one of…. In lower plants like the Pteridophytes, the branching of the veins is dichotomous. Leaflets (usually in pairs) are borne directly on rachis. Hence, the name palmate. 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 . There are various types of lobing or incision which ate discussed later in connection with leaf incision. Another such pitcher is found in the epiphytic climber Dischidia rafflesiana (Asclepiadaceae) from Assam. It bears the weight of the lamina and conducts water and food materials between the stem and leaf. (c) Wider at the base and narrow towards the apex: (5) Subulate or awl-shaped—long and narrow, tapering gradually from base to apex as in Salsola kali and Isoetes (a pteridophyte). This is the case in many aquatic plants as well. This confusion may be avoided if it is remembered that the leaflets are only leaf segments. (6) Ovate or egg-shaped—as in china-rose and banyan. 2. a thin layer or coating lying over another, as in certain minerals. The leaf spines on the main branches of Asparagus also act as hooks. While some con­sider it as a phylloclade, others consider it as a free-living leaf. Essay # 2. Develop­ment of spinous structures is a feature of the xerophytes. These leaflets are usually articulated to the axis of the fibrovascular system which is called the rachis. (15) Cuneate or wedge-shaped as in Pistia stratiotes. (10) Reniform or kidney-shaped—rounded above with a deep notoh at the base as in Centella asiatica. (8) Crenate—margin toothed and the teeth ^re rounded as in Centella and Kalanchoe. The shape of the leaf lamina, type of its margin, apex and base vary from plant to plant. Before sharing your knowledge on this site, please read the following pages: 1. The pinnae are dissected again into pinnules so that the leaflets (pinnules) are borne not on die rachis but on its branches as in Acacia nilotica , Mimosa pudica, Caesalpinia pulcherrima, etc. (6) Dentate—margin toothed, the teeth are pointed outward, i.e., at right angles, e.g., water-lily. What is the significance of transpiration? Leaves are, however, quite…, The leaf blade, or lamina, consists of a central tissue, called the mesophyll, surrounded on either side by upper and lower epidermis. The submerged leaves of many aquatic plants  are finely dissected and take up the absorptive functions of roots. In some plants the leaf has a swollen leaf base. Thus, a leaf, and most conspicuously its blade, is positioned directly under the blade two nodes above it. 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 the date-palm this spine is quite a hard structure. The ramifications are called veins and their arrangement is known as vena­tion. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Usually the lobes towards the apex are larger. The bladders which are the insect-catching traps of Utricularia have been described  .These are modified lobes of leaves. If the basal lobes fuse together after completely clasping the stem it seems that the stem has perforated the leaf. Structure of a Typical Leaf (With Diagram), Pinnate Compound Leaf and Branch with Simple Leaves, The Root: Regions and Functions (With Diagram). Single moisture readings using this moisture meter had mean execution time of ~ 1.0 min. Grass leaves are borne singly at the nodes and, with minor exception, are arranged in two vertical ranks. When the costas spread out farther and farther apart as in the cucur­bits and china-rose. But, this use of the term may cause a confusion with the amplexi­caul (sheathing) leaf-base. The whole compound leaf can never arise from the axil of another leaf which would have been the case if it were a twig. This is seen in Calotropis procera. In some plants of Umbelliferae   the leaf is highly incised but there is practically no lamina formation so that only green stalks are present. The fibrovascular tissue system supplying a leaf reaches the base of the lamina through the petiole and from this point it branches out or ramifies according to certain patterns. -nae (-ˌni) -nas. A compound leaf is sometimes confused with a twig bearing leaves. A very thin layer of material.. A thin plate or scale, such as the arch of a vertebra.. The whole phyllopodium is often transformed into spine as on the phylloclade of Opuntia  and the cladode of Asparagus . Which part of the male reproductive system store the sperm? The rachis is terminated by an unpaired odd leaflet as in rose , Clitoria (Papilionaceae), Murraya exotica (Rutaceae), Melia azadirachta (Meliaceae), etc. Learn more. Is this an example of necrosis or apoptosis? In lemons and oranges (Citrus spp ), the prophyll is a spine. ; (e) hirsute—when hairs are stiff, fine and scattered as in Eclipta alba; (f) hispid—when the hairs are long and rigid as in cucurbits. Cuneate bases are sharp-pointed, with an angle less than 45 degrees between opposite sides which form a wedge or triangular shape that tapers to a narrow region at the point of attachment of lamina with petiole. It is in this layer that photosynthesis occurs. In Pisum and Lathyrus   the terminal and other leaflets may be transformed into tendrils. A closer observation, however, shows that a very narrow lamina connects the lobes. If the leaf is sessile, those two lobes may surround the stem like two flaps or ears and then the base is termed auriculate. The blade is the major photosynthetic surface of the plant and appears green and flattened in a plane perpendicular to the stem. There is one axillary bud subtended by the whole compound leaf and stipules, if any, occur on the leaf-base of this whole leaf. Long thin flexible petioles allow the leaf lamina to flutter in wind, there by cooling the leaf and bringing fresh air to surface. 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. (6) Tendrillar—when the apex forms a tendril for climbing as in Gloriosa. As opposed to these compound leaves showing an extreme type of dissection, the ordinary entire or incised (including even the -sect types) leaves are known as simple leaves. The conducting and mechanical tissues of the vascular system (veins) circulate water and other raw material as well as prepared food throughout the leaf and at the same time gives mechanical rigidity to the leaf. The main functions of the lamina … It contains a prominent midrib at the center of the leaf blade which is the main vein. There is, usually, a middle prominent vein, which is known as the midrib. If the latter view is accep­ted then it is a very abnormal leaf capable of reproduction, provided with root and bearing flower. 3. the blade or expanded portion of a leaf. (1) Acute—when pointed and narrow as in mango. Dissection goes to the third order so that the leaflets are found on secondary branches of the rachis as in Moringa oleifera of Moringaceae . Answer Now and help others. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. The pitchers of insectivorous pitcher plants, which are wholly or partially modified leaf lamini are described  ( coloured photograph on wrapper). (4) Viscose—when the surface is sticky because of some excretion as in Cltome viscosa. Similarly, some palmately lobed leaves show the lobes arranged like the claw of a bird as in Cayratia pedata. In the first type the strong main veins give rise to finer branches which again branch repeatedly running into one another and forming a reticulum or network all over the leaf. TOS4. This indentation is sometimes so prominent that the leaf is said to be incised or lobed. Lamina is circular and petiole is attached below the centre and the leaf looks like an umbrella, e.g., lotus, Nelumbo nucifera (Fig. (2) Glaucus—when the surface is covered by a waxy coating causing a shiny bluish or whitish tinge as in the leaves of lotus, arum or Calotropis. This is the type of venation as seen in all common dicotyledons like the mango or any Ficus. 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