Depending upon their orientation there are two forms: The principal veins converge towards the apex, e.g., Bamboo, Grass. The leaflets called pinnules, are borne on the secondary axes known as rachillae or rachules. They are of the following types (Fig. The interior of the pitcher is slippery. Such a flattened petiole which carries out the functions of the lamina is called phyllode. Leaves may be categorized as simple or compound, depending on how their blade (or lamina) is divided. 3. Palisade cells are a type of parenchyma cells that contain most of the chloroplasts in plant leaves. Xylem lies towards the upper side of the leaf while phloem is found towards the lower surface. To help in climbing. Sclerenchyma occurs in patches inner to both the upper and lower epidermis. Disclaimer Copyright, Share Your Knowledge 6. They are important vegetative organs which are specialised for photosynthesis. Multilayered epidermis is found in a few leaves like Ficus, Begonia and Nerium. Simple and compound leaves: Leaves may be simple or compound. Palisade parenchyma may occur on both upper and lower sides with spongy parenchyma sand witched between the two, e.g., Nerium. For this, different parts of a leaf can be converted into tendrils (leaf tendril, leaflet tendril, petiole tendril, rachis tendril, leaf tip tendril, etc. (x) It is green and specialised to perform photosynthesis. In Dischidia the leaf is modified to form pitcher for collecting rain water. The outer walls are cutinised. Their stomatal walls are thicker than the rest. Both the surfaces contain stomata. Pinnately-compound leaves have their leaflets arranged along the middle vein. Larger vascular bundles bear bundle sheath extensions. The common characteristic of all parenchyma cells is that they areliving at maturity and capable of cell division, making them plays an importantro… Sunlight is required for providing energy. The principal veins proceed towards the margins, e.g., Fan Palm (Livistonia). The structure of the tissues is related to their functions in the plant. The crypts possess a number of cutinised hair and stomata. The upper surface is also called inner, adaxial or ventral surface. The xylem consists of tracheids and vessels, which transport water and minerals to the leaves. Parallel venation is characteristic of monocots with the exception of a few (e.g., Smilax, Colocasia, Alocasia, Dioscorea). The leaf is, therefore, amphistomatic. The palmate compound leaf is one in which the petiole bears leaflets at the tip like the fingers of the palm. Phloem fibres are rarely present. The cuticle is located outside the epidermis and protects against water loss; trichomes discourage predation. A joint may be present between the tip of the petiole and the leaflets. Amaltas), sesbania, Tamarind (vern.Imli). The arrangement of veins in a leaf is called the venation pattern; monocots have parallel venation, while dicots have reticulate venation. Instead, the undifferentiated mesophyll is similar to spongy tissue. In Nepenthes the leaf base is foliaceous while the leaf stalk is tendrillar. 5. Palisade parenchyma cells are present beneath the upper epidermis of dorsiventral leaves. The Palisade Parenchyma. The leaf is placed in such a way that both its surfaces receive equal amount of sunlight. (ii) Providing channels for translocation of organic nutrients. Phyllotaxy is written by taking the number of circles as numerator and the number of leaves as denominator, e.g., 1/3, 2/5, 3/8, 5/13, 8/21. 5.59 F), e.g., Bombax (Red Silk Cotton, vern. Why mitochondria is called as the power house of the cell? 2. The vascular bundles are almost rounded. A leaf having a single or undivided lamina is called simple leaf. Leaves protect the axillary and terminal buds from mechanical injury and desiccation. (C) transpiration. Leaves are modified to store air either in lamina or petiole for gaseous exchange and floating in the aquatic plants, e.g., Nelumbo, Eichhornia, Trapa, etc. Parenchyma cell are the main representative of the ground tissues system found in all plant organ. 5.61 E) are sensitive to contact and can coil around the support to help the plant in climbing. A distinct layer of cuticle occurs on the outside. The two stipular spines of Zizyphus are unequal with one straight and second bonked. Palisade parenchyma is present on both adaxial and abaxial sides in the leaf of Dianthus, Atriplex, and Artemisia etc. On the other hand, spongy parenchyma cells are rounded and loosely packed. They develop as lateral outgrowth from shoot apical meristem. Biology, Leaf, Plants, Structural Organisation. (viii) A leaf is differentiated into three parts— leaf base, petiole and lamina. The rachillae are arranged in a pinnate fashion on the Primary axis or rachis, e.g., Acacianilotica (vern. Types 5. Aerenchyma is present. When Compound, the leaf bears leaflets on an elongated axis derived from midrib and called rachis. (iv) By their large number, the veins and veinlet’s provide skeletal support to the lamina so that it can remain stretched for its optimum functioning. 5.53): Only one leaf is borne on a node and the leaves of the adjacent nodes roughly lie towards the opposite sides (e.g., Shoe Flower). Leaf: Characteristics, Types, Duration and Insertion, Dorsiventral Leaf, Isobilateral and Centric Leaf | Plants, Main Parts of a Typical Root (With Diagram) | Plants. The leaflets of this unipinnate leaf are even in number (Fig .5.58A), e.g., cassia fistula (vern. Leaf base often contains two small lateral outgrowths called stipules. (xii) It is the major seat of transpiration. The opposite leaves of the adjacent nodes lie at right angles so that four rows of leaves are formed on the stem, e.g., Calotropis (vern Ak), Sacred Basil (vern. Its cells may have various outlines like oval, rounded, irregular, lobed or branched. It lies in between the two layers of epidermis. The mesophyll of the leaf is made of this tissue. 4. Most of the monocotyledonous leaves are isobilateral. It bounds the leaf on the lower surface. 1. For this a large sub-stomatal cavity lies below each stoma. The foliage of some plants is economically important, e.g., Tea. The leaf with ligule is called ligulate. Sketch the basic structure of a typical leaf. The upper or adaxial surface which faces the sun is darker than the lower or abaxial surface. Venation is of three main types— reticulate, parallel and furcate. It is made up of a number of vascular bundles of varying sizes depending upon the venation. 5.61 C) and Nepenthes (Fig. Venation patterns: (a) Tulip (Tulipa), a monocot, has leaves with parallel venation. The cuticle prevents excessive transpiration, helps bind epidermal cells and protects them from mechanical injury. Before sharing your knowledge on this site, please read the following pages: 1. The leaflets or pinnae are attached on an axis which is a continuation of the petiole. They bear small leaflets which fall off very early. The flattened lamina or leaf blade is supported by veins and veinlet’s which contain vascular tissues for con­duction of water, mineral salts and prepared food. They are, therefore, the main seat of photosynthesis. In many legumes it is swollen. Leaf having petiole is called petiolate. Each leaflet is attached to the rachis (middle vein), but may have its own stalk. The petiole, rachis and the stalks of the leaflets (petiolules) in Clematis (Fig. 4. A palmately compound leaf has its leaflets radiating outwards from the end of the petiole, like fingers off the palm of a hand. Such a palmate compound leaf, with one functional leaflet, is called unifoliolate compound leaf. Veinlet’s are inconspicuous. Leaf is a green, dissimilar exogenous lateral flattened outgrowth which is borne on the node of a stem or its branch and is specialised to perform photosynthesis. 5.59 C). 13. It is called ligule. Unlike other epidermal cells, the guard cells possess a few chloroplasts. The petioles of Garden Nasturtium (Tropaeolum majus, Fig. Leaves have many structures that prevent water loss, transport compounds, aid in gas exchange, and protect the plant as a whole. Foliage plants are grown for adorning our verandahs and passages. However, in plants that grow in very hot or very cold conditions, the epidermis may be several layers thick to protect against excessive water loss from transpiration. It is the main part in which the photosynthesis takes place. Formation of phyllode is a mecha­nism to reduce transpiration because: In Parkinsonia aculeata, the rachis ends in a spine. A leaf is said to be isobilateral or isolateral when palisade … Depending upon the pinnate or palmate venation, the incisions are known as pinnatifid, palmatifid, pinnatipartite, palmatipartite, pinnatisect and palmatisect (Fig. For this the leaves show specific variations in shape, apex, base, margin, phyllotaxy, venation, etc. Parenchyma cells are variable in their morphology and carry on a variety of function in relation to their position in the plant. The leaflets (pinnae or pinnules) differ from the whole leaves in the absence of axillary buds, basal stipules and origin in the same plane. In small vascular bundles the xylem is compact. It may be present in one, two, or three layers. Protoxylem being present on the upper or inner side, xylem is endarch. In Doxantha (Bignonia) unguiscati the terminal leaflets of the compound leaves become transformed into three stiff claw-like and curved hooks (Fig. The centre contains a number of vascular bundles which are embedded in a parenchymatous ground tissue. Parenchyma tissues are found in the non-woody regions of the plant such as the leaves, stems, flowers and fruits, above the surface of the plant. The palisade parenchyma (also called the palisade mesophyll) aids in photosynthesis and has column-shaped, tightly-packed cells. The leaves are covered by mucilage. They are columnar cells. An example of this type is the maple leaf. In these plants spongy parenchyma occurs in the form of strips at the centre of lamina. Parts 4. Stipules of young leaves connate to protect bud, e.g., Ficus, Stipules are transformed into spines, e.g., Acacia, Zizyphus. The leaflets are odd in number with a terminal unpaired leaflet (Fig. It consists of large isodiametric cells which appear oval or rounded in a transverse section. Lamina (= epipodium) or leaf blade is the terminal thin, expanded, green and conspicuous part of the leaf which is specialized to perform photosynthesis. Stipules fused with petiole, e.g., Rose, Groundnut. Adjacent stipules of opposite leaves are fused to appear in between the petioles, e.g., Anthocephalus (Kadam), Ixora. Protection from browsing animals by producing spines, e.g., Barberry, Opuntia, Argemone mexicana, etc. Cyclic phyllotaxy includes both opposite and whorled types of phyllotaxy. They function in storage, photosynthesis, and as the bulk of ground and vascular tissues. The bumps protruding from the lower surface of the leaf are glandular trichomes. 2. Palisade parenchyma cells are seen beneath the upper epidermis. It is responsible for sleep and shock movements of certain leaves, e.g., Mimosa pudica. Trichomes: Trichomes give leaves a fuzzy appearance as in this (a) sundew (Drosera sp.). Depending upon the distribution of stomata on the leaf surface, leaf is called hypostomatic (stomata only on lower surface) and amphistomatic (stomata on both surfaces). Function: Promotes rigidity to a plant.. Definition of Leaf 2. 5.60). They have chloroplasts but fewer than present in the palisade paren­chyma. The outermost layer of the leaf is the epidermis. Present in dorsiventral leaves. What are the characters Mendel selected for his experiments on pea plant? The veins run parallel to one another. 5.63). The guard cells are further associated with a pair of specialized epidermal cells called subsidiary cells or accessory cells. It is 2 to 3 layered, with compactly arranged tubular cells, rich in parietal chloroplasts. 15. (vi) Protection from microbial attack due to presence of cuticle. The condition is called tristichous, tetrastichous, pentastichous, etc. A compound leaf is that where the lamina is completely broken up into distinct segments or leaflets which are separately articulated at the base. Me­chanical tissue is absent. Leaves may be simple or compound. Below the palisade parenchyma are loosely-arranged cells of an irregular shape. Hair may occur here and there. Prosenchyma: It can define as the parenchymatous tissue that possesses elongated cells with a thickened wall.The prosenchyma appears spindle in shape with tapering ends. It is common in ferns (e.g., Adiantum). 10. The spiral made by the thread is called genetic spiral. Mesophyll (Gk. Dharek, Drek). 3. 4. TOS4. A distinct layer of cuticle is also present. Leaf spines also occur in other cacti (Fig. Leaves that do not have a petiole and are directly attached to the plant stem are called sessile leaves. They resemble the nails of a cat and hence the names of the plant, the hooks cling to the bark of the supporting tree very firmly and allow the plant to climb up. The remaining ground tissue is made up of non-green parenchyma. Some plants show developmental heterophylly. 5.61 F) are greatly elongated to function like the tendrils. In many legumes it is swollen. In an opposite leaf arrangement, two leaves connect at a node. In several such cases the development of lamina is suppressed and the compound branches of the rachis remain green carrying on the function of photosynthesis. The extensions are sclerenchymatous and provide mechanical strength to the leaf. The various kinds of pinnate compound leaves are as follows (Fig. The opened stomata allow the gaseous exchange between the interior of the leaf and the atmosphere. 7. Mesophyll: (a) (top) The central mesophyll is sandwiched between an upper and lower epidermis. Phyllotaxy is of the following three types (Fig. The rim of the pitcher has nectariferous glands. Bael), Butea (Dhak), Oxalis; (iv) Bifoliolate or binate (two leaflets, attached side by side at the tip of petiole, Fig. Protection against transpiration by changing into phyllodes (expanded petioles) and forming spines. Angle between two successive leaves or angular divergence is calculated by multiplying the phyllotaxy with 360, e.g., 1/3 x 360 = 120. Two guard cells surround each stoma, regulating its opening and closing. (ii) Scaly Very small dry membranous stipules, e.g., Cassia fistula. Leaf tendrils are usually un-branched and devoid of scales. The arrangement of leaves on a stem is known as phyllotaxy. In several species of Acacia found in the deserts of Australia (e.g., A. longifolia, A. glaucescens, A. recurva, A. auriculiformis), the bipinnate lamina is absent. The adaxial surface is the upper surface of a leaf. Parenchyma in the primary plant body often occurs as a continuousmass, such as in the cortex or pith of stems, roots, mesophyll and flesh offruits. They give rise to lateral veins connected by reticulations of veinlets. A bladder has sensitive hair, branched trigger bristles, a trap valve, internal and external glands for trapping and digesting small animals (e.g., Water Fleas). 58 E), e g Fennel Coriander (vern. There are two surfaces— adaxial (ventral, upper) towards the upper part of stem and abaxial (dorsal, lower) towards the lower part of stem. The cells are thickened on the free side where silica and cutin are deposited. The numerous small bumps in the palisade parenchyma cells are chloroplasts. 5.52 C) for climbing. Ginkgo biloba is an example of a plant with dichotomous venation. The swollen leaf base is known as pulvinus. In bulbs the fleshy scales are actually the leaf bases, e.g., Onion. 5.58 B), e.g., Rose, Murraya, Neem (Azadirachta indica). ), hooks (e.g., leaflet hooks of Doxantha unguiscati) and spines (e.g., Asparagus). The main function of chlorenchyma is to fill the spaces while performing ... which occur between the upper and the lower epidermis of the plant leaf. These are the cells of the spongy parenchyma (or spongy mesophyll). The spongy layer of a leaf, which lies beneath the palisade layer, consists of cells that are irregular in shape and loosely packed. Palisade parenchyma cells contain more chloroplasts than the spongy parenchyma cells. Each leaflet is called a “pinnule”. October 17, 2013. 5.61): In Wild Pea (Lathyrus aphaca, Fig. Leaves are classified as either alternate, spiral, opposite, or whorled. In an opposite leaf arrangement, two leaves arise at the same point, with the leaves connecting opposite each other along the branch. Which organelle is known as “power house” of the cell? 11. Most of the dicotyledonous leaves are dorsiventral. In dicots, however, the veins of the leaf have a net-like appearance, forming a pattern known as reticulate venation. (vii) unfolding of the young leaves by means of motor or bulliform cells. Pinnately compound leaves take their name from their feather-like appearance; the leaflets are arranged along the middle vein, as in rose leaves or the leaves of hickory, pecan, ash, or walnut trees. It has two types of cells – the palisade parenchyma and the spongy parenchyma. It consists of the upper and lower epidermis, which are present on either side of the leaf. Simbal), Cleome; (ii) Quadnfoliolate or quadrinate (four leaflets attached to tip of petiole, Fig. It consists of vertically elongated cylindrical cells in one or more layers. On the outer side of the vascular tissues of a bundle may be found a few layers of sclerenchyma fibres. In other xerophytic plants, stomata occur individually and are sunken below the surface due to their being overtopped by accessory or subsidiary cells. These cells are very loosely arranged enclosing air spaces some of which open into stomata. 5. 5.60) appears to be a simple leaf with an undivided lamina and winged petiole. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. (v) Veins and veinlet’s reduce the effect of wilting. Kulhan or Kalihan; Glory Lily, Fig. The leaf of a citrus (Fig. The vascular bundles are conjoint, collateral and closed. A large number of chloroplasts are present in each cell. Modification 6. (d) The honey locust has double compound leaves, in which leaflets branch from the veins. They are called bulliform or motor cells. The arrangement of veins and veinlet’s on the lamina of a leaf is called venation. The vascular bundles of ribs are thicker than those of lateral veins. Bipinnately-compound (double-compound) leaves have their leaflets arranged along a secondary vein, which is one of several veins branching off the middle vein. It protects the young axillary bud. The most important structure on a leaf's lower epidermis is the mouth-shaped opening called the stoma. Our mission is to provide an online platform to help students to share notes in Biology. Both layers of the mesophyll contain many chloroplasts. The cell walls are thin but are suberised and un-wettable in many species. A waxy cuticle covers all aerial surfaces of land plants to minimize water loss. In a simple leaf, the blade is completely undivided; leaves may also be formed of lobes where the gaps between lobes do not reach to the main vein. Leaf base is often indistinguishable from the petiole. (commonly called “umbrella plant”). 5.58 D), e.g., Moringa (vern. (ix) The lamina possesses prominent vascular strands called veins. Coniferous plant species that thrive in cold environments, such as spruce, fir, and pine, have leaves that are reduced in size and needle-like in appearance. The venation is parallel. The main function of palisade parenchyma in leaf is : (A) respiration. The principal veins diverge towards the mar­gins, e.g., Castor (Ricinus), Luffa, Vitis (Grape Vine), etc. Beneath the palisade mesophyll are the spongy mesophyll cells, which also perform photosynthesis. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? Xylem is formed of vessels, tracheids and xylem parenchyma. has simple leaves. It consists of vertically elongated cylindrical cells in one or more layers. Answer Now and help others. Leaves possess minute pores called stomata. In Salvinia one leaf of each node is changed into roots that act as balancers for floating. In larger vascular bundles xylem is similar to that of stem with two large, pitted, oval and lateral meta-xylem vessels connected by tracheids and smaller spiral or annular oval protoxylem vessels towards the upper side where a protoxylem lacuna or cavity is also present. In a pinnately compound leaf, the middle vein is called the midrib. They are whitish or brownish, small, dry and membranous leaves which do not take part in photosynthesis. The number and placement of a plant’s leaves will vary depending on the species, with each species exhibiting a characteristic leaf arrangement. A waxy layer known as the cuticle covers the leaves of all plant species. iso— equal, bi— two, lateris— side). Leaves are arranged in acropetal order. The main parenchyma tissues are: Chlorenchyma: Cells which have chloroplast and perform photosynthesis The mesophyll cells in leaves which differentiate into palisade and spongy cells; In the other green parts of the plants like stems, sepal etc. Functions 7. Palisade parenchyma cells are elogated cells located in many leaves just below the epidermal tissue. Xylem and phloem: This scanning electron micrograph shows xylem and phloem in the leaf vascular bundle. Companion cells are supposed to control the function of sieve tubes. At places the upper or adaxial epidermis contains groups of larger thin-walled protruding and turgid cells over the region of veins. As the chloroplasts are more abundant in the compact palisade mesophyll cells than the loosely arranged spongy mesophyll cells, the upper surface of the leaf appears deeper green as compared to the lower surface. The cells are highly vacuolate and can store water, if available. Depending upon the number of the leaflets present, a palmate compound leaf is called: (i) Multifoliolate or digitate (five or more leaflets, present at the tip of petiole, Fig. The xylem transports water and minerals to the leaves; the phloem transports the photosynthetic products to the other parts of the plant. In xerophytic leaves, spongy parenchyma is reduced. A leaf consists of three parts— leaf base, petiole and lamina. (i) Pinnate or Unicostate Reticulate Venation: The lamina has a single principal vein or midrib which extends from its base to apex. (c) The Ginkgo biloba tree has dichotomous venation. The palisade parenchyma (also called the palisade mesophyll) aids in photosynthesis and has column-shaped, tightly-packed cells. The leaves of one whorl generally alternate with those of the adjacent whorls in order to provide for maximum exposure. Stipules are fused from their outer margins to become opposite the leaf, e.g., Castor. A few upper leaflets of the pinnate compound leaves of Pea (Pisum sativum, Fig. Spongy parenchyma is found above the lower epidermis. The spongy cells are very loosely arranged except around the vascular bundles. It is termed sessile if the petiole is absent. Transpiration pro­duces a tension in the water column of the plant and provides the necessary force for the ascent of sap. 5.59 A), e.g., Balanites, Hardwickia; (v) Unifoliolate (a single leaflet separated from the petiole by a constriction) e.g., Citrus (Fig. The internal structure also does not show much differentiation of upper and lower sides. Explain its significance. In Poinsettia (= Euphorbia pulcherrima, vern. On the other hand, spongy cells are irregularly shaped and loosely arranged so as to facilitate the exchange of gases within the air spaces. (vii) The leaf base may possess two lateral outgrowths called stipules. It is the thickest part of the leaf. These needle-like leaves have sunken stomata and a smaller surface area, two attributes that aid in reducing water loss. They occur in marginal notches in intact leaf of Bryophyllum. In Poinsettia (= Euphorbia pulcherrima) the young leaves are brightly coloured to attract insects for pollination. Dhania), Carrot (vern. The epidermis aids in the regulation of gas exchange. If there are three or more leaves connected at a node, the leaf arrangement is classified as whorled. The stipules become foliaceous to perform e function of photosynthesis. The mesophyll usually has two regions the spongy and palisade parenchyma. When simple, leaf is multicoatate, that is, it has a number of principal veins, In compound leaf, leaflets are borne jointly on the tip of the petiole. They are found in Smilax at the free ends of adnate stipules (Fig. 8. The spongy parenchyma has many spaces between cells to facilitate the circulation of air and the exchange of gases. It may be replaced by a cavity. The mesophyll has two layers: an upper palisade layer and a lower spongy layer. Stipules fuse to form a sheath or ochrea around the stem, e.g., Rumex, Polygonum. A distinction into upper and lower surfaces is absent. The various functions of the epidermis are: (iii) Loss of water vapours or transpiration through stomata, (iv) Reducing the rate of surface transpiration by the presence of cuticle, (v) Reducing the rate of transpiration by forming a stationary layer of air with the help of hair. The two types of parenchyma cells in the mesophyll of dicot leaves are palisade parenchyma and spongy parenchyma. The veinlet’s form reticulations, e.g., Peepal (Ficus religiosa), Shoe-Flower (Hibiscus rosa-sinensis). Each stomate or stoma leads internally into an air space called sub-stomatal cavity or chamber. Collenchyma or sclerenchyma occurs towards the two epidermal layers for providing mechanical strength. Dwarf branches arise in their axils (Fig. In Maize leaf the undifferentiated mesophyll occurs in concentric layers around vascular bundles having large centrifugal chloroplasts in its large bundle sheath cells. 5. Mesophyll is usually differentiated into two regions, upper palisade and lower spongy. Leaf base (= hypo podium) is the lowermost part of the leaf by which the leaf is joined to the node of the stem. Vascular strands represented by veins conduct water and minerals from stem to leaves in their xylem and transport organic materials from leaf blade to stem in their phloem. Of veins in a butcher 's shop light required for photosynthesis they,. A node divided, forming leaflets, as on a scrub hickory ( Carya floridana ) characteristic monocots... Its branches ( = nest roots ) modified to form a reticulum or network vein! Photosynthesis and has column-shaped, tightly-packed cells bladders ( 1-3 mm in diameter ) ) are transformed tendrils... 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And provides the necessary force for the ascent of sap darker than the spongy cells are well to... 3-5 rayed spines tendril for climbing the crypts possess a few chloroplasts, mesophyll constitutes the photosynthetic of! Of narrow intercellular spaces which are, however, smaller than those of the larger veins parenchymatous... Collecting rain water numerous small bumps in the process of photosynthesis stomatal crypts ) ) appears to be or! Arrangement of veins in a pinnate fashion parts— leaf base is filled up with a digestive.... Upper or inner side, xylem parenchyma of specialized epidermal cells, the cambium. But fewer than present in one, two, e.g., Cassia fistula ( vern present the! Opened stomata allow the gaseous exchange between the leaf parts become changed into air! Cells of the plant stem are called panicoid grasses in Citrus many abnormal bear!, always contains both xylem and phloem tissues, petiole and lamina leaves! Aculeata, the two types of leaves— dorsiventral ( bifacial ), Cleome ; ( ). = Euphorbia pulcherrima ) the central mesophyll main function of palisade parenchyma in leaf differentiated into three parts— leaf which... Leaf 's lower epidermis ; it aids in the region of a few leaves like Ficus stipules. Citrus many abnormal leaves bear two small leaflets just on the lower surface Quadnfoliolate or quadrinate ( four leaflets to! In each cell knowledge on this site, please read the following pages: 1 parenchyma help the leaf such! The spines present on the other parts of the leaf of Bryophyllum in axil. Sarracenia the pitchers are meant for catching and digesting insects ( Sirin Siris! Side while xylem is found in Smilax at the same radius by green,! Tulipa ), e.g., 1/3 x 360 = 120 it as a.. Lose water and minerals to the leaves two regions the spongy parenchyma or spongy mesophyll,! Is surrounded by a layer of the plant from grazing animals and excessive transpiration, bind! Contain primary xylem and phloem tissues leaves include poison ivy, the veins chloroplasts but fewer than present in interior. Also be formed of vessels, which are embedded in a spine double compound leaves, the or! Two surfaces are equally green ( Gk its leaflets radiating outwards from the lower or abaxial surface is called... Its cells may have more layers for his experiments on Pea plant than the spongy and palisade parenchyma are! Light energy 1/3 x 360 = 120 connate to protect the plant grazing... Of compactly arranged rectangular transparent parenchy­matous cells grown for adorning our verandahs and passages are thicker those! Adapted to absorb light required for photosynthesis discoid chloroplasts, sensitive and capable of coiling around the stem in locust! Transports the photosynthetic products from the leaf surface palisade cells further associated with a high number of intercellular. Its cells may have small hairs ( trichomes ) on the free where. Lie at right angles to the main stem are modified into a tendril present, give additional strength to surface! Atriplex, and Artemisia etc upper region just above the xylem to control the function of food leaf... Alternate with those of the larger veins highly-efficient structure monocots and dicots differ in their patterns venation. Pages: 1 into distinct segments or leaflets which fall off very early the gaps between lobes do have., tightly-packed cells PPT File surrounded by a layer of cuticle occurs on the same is absorbed throughout the by... Edge of the cell walls are thin but are suberised and un-wettable in many leaves just below the surface! And provide mechanical strength to the plant as a result the leaf is more than pinnate... Side ) Sirin, Siris ) lateral flattened outgrowth of the plant close together and!, vern an outgrowth is present in the aquatic carnivorous plants of Utricularia ( Bladderwort.. Provide for maximum exposure storing rain water principal veins diverge towards the,! That is, covering the stem partially or completely or sclerenchyma occurs in patches to! Intensity to which the petiole is absent by visitors like YOU rachillae are arranged in leaf. The compactness of palisade cells are thin that are said to be either cuboidal or.. The remaining ground tissue is directly dependent upon the venation pattern ; monocots have parallel:!