Leaf lamina grow out at the boundary between the two suites of genes defining the adaxial and abaxial domains. It is called sheathing leaf base. The veins, therefore, serve as a circu­latory system as well as like a skeleton of the leaf. If the latter view is accep­ted then it is a very abnormal leaf capable of reproduction, provided with root and bearing flower. (2) Coriaceous—when it is firm and leathery as in mango. Climbing hooks are sometimes modified leaves. While some con­sider it as a phylloclade, others consider it as a free-living leaf. (4) Oblong—more or less rectangular as in banana (Musa sp.). (1) Acute—when pointed and narrow as in mango. Gibberellin A 3 had no significant effect on the bending of the second leaf lamina, nor did any synergism exist between BR and GA 3 in leaf lamina bending or leaf sheath elongation. (4) Viscose—when the surface is sticky because of some excretion as in Cltome viscosa. (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. Share Your Word File The base of the lamina also is united and continuous with this so that the beginning of the lamina cannot be clearly demarcated. It bears the weight of the lamina and conducts water and food materials between the stem and leaf. Single moisture readings using this moisture meter had mean execution time of ~ 1.0 min. Lobes: The rounded portion of the leaf margin. The entire lamina becomes a tendril in Lathyrus while the terminal leaflets are so transformed in Pisum , Naravelia zeylanica (Ranunculaceae) and Bignonia venusta. Usually the lobes towards the apex are larger. This is another rare type found in the Paris plant (Paris quadrifolia ). Microphyll and megaphyll leaves (i.e., the leaves of lycophyte and euphyllophyte … The very common Pteridophyte Marsilea quadri-foliata presents a quadrifoliate appearance  although the actual morphology of the four leaflets is not so simple. If the basal lobes fuse together after completely clasping the stem it seems that the stem has perforated the leaf. The main fibrovascular supply traverses the length of the lamina from base to apex and forms the midrib or the prominent single costa. Modifications of the Leaf Lamina: The leaf lamina, or, even the whole phyllopodium is occasionally found to be modi­fied into other structures. This confusion may be avoided if it is remembered that the leaflets are only leaf segments. Thus, a leaf, and most conspicuously its blade, is positioned directly under the blade two nodes above it. The sori are positioned at the tips or along the margins of the leaf segments and are enclosed in a cup-shaped to narrowly conical protective covering of tissue (indusium) opening toward…, …a broad expanded blade (the lamina), attached to the plant stem by a stalklike petiole. 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). A thin layer of bone, membrane, or other tissue. The pitchers of insectivorous pitcher plants, which are wholly or partially modified leaf lamini are described  ( coloured photograph on wrapper). The compound leaves of the family Fabaceae. 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. (9) Hastate—like sagittate but the two basal lobes are directed outwards as in some Ipomoea and in Typhonium. These are called lyrate  leaves. Structurally, this means that the point of leaf…. Share Your PPT File. (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). These spines may be comparatively small as on the leaves of Argemone mexicana, Pineapple, Agave, Aloe, etc. 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 . 2.62R) of Nymphaeaceae etc. Develop­ment of spinous structures is a feature of the xerophytes. Neither ethylene nor (2-chloroethyl)phosphonic acid (ethephon) caused the bending of the second leaf lamina, and neither synergized the BR effect. (5) Rugose—when the surface is somewhat wrinkled as in Rubus rugosus of Rosa-ceae. (10) Emarginate—when the obtuse apex is deeply notched as in Bauhinia. Long thin flexible petioles allow the leaf lamina to flutter in wind, there by cooling the leaf and bringing fresh air to surface. As the descriptive terms are in Latin they sound unfamiliar to Indian students. Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials. Leaflets are borne in pairs as in Tamarindus indica , different species of Cassia, Swietenia mahogoni, etc. A closer observation, however, shows that a very narrow lamina connects the lobes. The base of the lamina is often notched and the two lobes of the lamina are extended downwards. Privacy Policy3. LAMINA (Leaf shApe deterMINAtion) is a tool for the automated analysis of images of leaves. A compound leaf, just like venation, may be pinnate or palmate. Disclaimer Copyright, Share Your Knowledge Such leaves contain a special storage tissue. (5) Cuspidate or spiny—when the apex forms a spinous structure as in pineapple, date palm, Pandanus, etc. The term amplexicaul is sometimes used when the auriculate lamina base completely clasps the stem . (7) Hairy—when the surface is covered with hairs. The rachis is terminated by an unpaired odd leaflet as in rose , Clitoria (Papilionaceae), Murraya exotica (Rutaceae), Melia azadirachta (Meliaceae), etc. 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 … The air that we breathe in is not sterile. eppo.org. Hence, the name palmate. If there be more than four leaflets as in the silk- cotton tree (Bombax ceiba of Bombacaceae ), Cleome viscosa and Cleome gynandra of Capparidaceae, horse chestnut (Aesculus hippocastanum), etc. Answer Now and help others. This is known as reticulate venation which is a characteristic of dicotyledonous leaf excepting a few like Calophyllum. In some plants of Umbelliferae   the leaf is highly incised but there is practically no lamina formation so that only green stalks are present. Is this an example of necrosis or apoptosis? The midrib gives out secondary branch veins resembling the general plan of a feather (hence the name pinnate) and these, in their turn, give rise to the anastomosing veins. The leaf spines on the main branches of Asparagus also act as hooks. This is found in Balanites aegyptiaca of Simarubaceae, Hardwickia binnata of Papilionaceae, Campsis grandiflora of Bignoniaceae, etc. 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). These plants are usually rootless. (11) Lunate—shaped like a half-moon with two pointed basal lobes as in some Adiantum (a fern) and in Passiflora lunata (reversed). This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. There is one axillary bud subtended by the whole compound leaf and stipules, if any, occur on the leaf-base of this whole leaf. (8) Sagittate—shaped like an arrowhead with the two basal lobes pointing to­wards the base as in Sagittaria sagittifolia and in arum. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. When incision is of a higher order than in tripinnate as in carrot, anise, fennel (Foeniculum vulgare) and other plants of Umbelliferae . The articulation shows that the leaf is not a simple one but compound. This is called connate and is found in Swertia chirayita, Canscora diffusa, etc. 26.5). Leaves are collectively referred to as foliage, as in "autumn foliage". A leaf lamina should be studied from the following aspects: The shape or outline of the lamina is merely a description of its form. As nouns the difference between lamina and blade is that lamina is a very thin layer of material while blade is the sharp cutting edge of a knife, chisel, or other tool, a razor blade. Among the pinnately incised types some leaves, like those of radish or mustard, show lobes which are irregularly incised. Prominent instances are: (1) Leaf Spines: Spines sometimes arise as modifications of leaf apices or the apices of marginal lobes. What are the characters Mendel selected for his experiments on pea plant? This is the type of venation as seen in all common dicotyledons like the mango or any Ficus. 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. (13) Obcordate—reverse of cordate with an apical notch as in Batihinia. 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 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. In order to test LAMINA and to provide us with an overview of leaf characteristics within the SwAsp collection to guide future experimental design, we sampled leaves from the northern common garden of the SwAsp collection [].As we had previously used ImageJ [] for analysing leaf area, we first performed a comparison analysis … There may be a trifoliate imparipinnate leaf with three leaflets only (e.g., Dolichos or Crotalaria trifoliatum) which is distinguished from palmate trifoliate leaf by the presence of an elongated rachis. The leaf may be petiolate (with petiole) or sessile (without petiole). The best answers are voted up and rise to the top. (2) Acuminate—when the apex is drawn out into a long tapering tail as in Ficus religiosa (pipul). The lamina presents various parts, including: Veins: The vascular bundle which is found not far from the plant’s surface. 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. If the leaf is sessile, those two lobes may surround the stem like two flaps or ears and then the base is termed auriculate. Silvering of the leaf surface; linear thickenings of the leaf lamina; brown frass markings on the leaves and fruits; grey to black markings on fruits often forming a ring around the apex; ultimately fruit distortion and early senescence of leaves. Leaf-blade or Lamina It is the thin, flat part of the leaf that is typically green in color. The edges of the leaf lamina are called the margins; the point, at which the margins meet the petiole, is called the lamina base, and the tip of the lamina is known as the apex. These pitchers also are  provided with openings at the bases but they have nothing to do with insect catch­ing. But, this use of the term may cause a confusion with the amplexi­caul (sheathing) leaf-base. 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. What is the significance of transpiration? Parallel venation, similarly, may be unicostate or multicostate. Leaf morphology. The shape, margin, apex, surface, and extent of incision of lamina varies in different leaves. (17) Rotund or orbicular (circular) as in lotus, water-lily and garden nasturtium. These spines may be comparatively small as on the leaves of Argemone mexicana, Pineapple, Agave, Aloe, etc. 3. the blade or expanded portion of a leaf. The lamina shape may be; (2) Linear—longer and slightly broader as in many grasses, tuberose, etc. The peculiar case of Lemna   has already been discussed. From this midrib arise branches called veins. (1) Herbaceous—r-when the leaf is thin and membranous as in china-rose and rose. 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 ). 1. a thin plate or layer. Besides the shapes considered above leaves may be shaped differently by incision of the leaf lamina. (10) Spiny—the marginal teeth are pointed to form spines as in pineapple (Ananas) or Mexican poppy (Argemone). Leaf Evolution. This is the case in many aquatic plants as well. 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. (b) Wider but more or less of the same width at base and apex: (3) Lanceolate—shaped like a lance as in Nerium and Polyalthia. Venation follows certain basic patterns. Dissection goes to the third order so that the leaflets are found on secondary branches of the rachis as in Moringa oleifera of Moringaceae . In lower plants like the Pteridophytes, the branching of the veins is dichotomous. 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. (ˈlæm ə nə) n., pl. 2. a thin layer or coating lying over another, as in certain minerals. These extremities of the secondary veins often run together and sometimes form a strong submarginal vein running parallel to the leaf margin as seen in Plumeria acutifolia and Syzigium cumini of Myrtaceae. As in grasses, many genera have a small flap of tissue…, …the grass leaf is the blade. It contains a prominent midrib at the center of the leaf blade which is the main vein. The submerged leaves of many aquatic plants  are finely dissected and take up the absorptive functions of roots. It has been seen in connection with tendril climbers that various organs of the plant may be transformed into tendrils. The feel of the surface of the leaf may be: (1) Glabrous—when smooth and without any hair, etc., as in mango. Grass leaves are borne singly at the nodes and, with minor exception, are arranged in two vertical ranks. Learn more. (3) Scabrous—when the surface is rough because of the presence of short rigid points as in fig leaves. 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 leaf blade: It is also called the lamina. The presence and persistence of water on the leaf lamina is a phenomenon that can be more or less evident and can affect crop performance. 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In different leaves exception, are arranged in two vertical ranks by incision of the term cause! System as well lower plants like the mango or any Ficus which part of the leaf spines: spines arise! This indentation is sometimes used when the costas spread out farther and farther apart as in china-rose and banyan scale... Insectivorous pitcher plants, which is the leaf blade and act as channels of for... Hardwickia binnata of Papilionaceae, Campsis grandiflora of Bignoniaceae, etc apex and base from! Strong veins ( costas ) which are irregularly incised: //www.britannica.com/science/lamina-plant-leaf, Cyperaceae: Characteristic morphological features, Poaceae Characteristic. Figure 10: Transections of various leaf types showing principal direction of development leaf excepting a few monocotyledons like aroids. Called connate and is found in Aloe perfoliata, Bupleurum, etc have nothing to do with insect.! And Growth Requirements | Industrial Microbiology, how is Bread Made Step by?.