These all developed thorns or spines to prevent grazing by herbivores of the leaves and stems and would severely damage the plant. In some plants leaves produce buds called epiphyllous buds and help in vegetative propagation. Any part of the leaf may get modified in to spine. In many respects, the pattern of spine formation is similar to that which occurs in the development of thorns from lateral shoots. The swollen-thorn acacias of Central America actually have enlarged, hollowed-out, stipular spines occupied by stinging ants. These are modified leaves, e.g. These are modified leaves, e.g. Each leaf has a very different shape and function, yet all are homologous structures, derived from a common ancestral form. in Crataegus crus-galli and Carissa macrocarpa). Phyllode is a petiole modified into a leaf-like structure. A., "Hunter" Publisher: Buccaneer Books, 1993, https://books.google.com/books?id=gAv8CAAAQBAJ&pg=PA80, "Cross-Section Through the Prickle of a Rose", https://en.wikipedia.org/w/index.php?title=Thorns,_spines,_and_prickles&oldid=995100554, Articles with unsourced statements from May 2020, Wikipedia articles needing page number citations from April 2019, Wikipedia articles incorporating a citation from Collier's Encyclopedia, Wikipedia articles incorporating citation to the NSRW, Wikipedia articles incorporating citation to the NSRW with an wstitle parameter, Creative Commons Attribution-ShareAlike License, a tiny point at the tip of the leaf (mucronate leaves) (, This page was last edited on 19 December 2020, at 06:20. Photosynthesis is carried out by the fleshy green stems. Plants like Pistia possess stem which is modified into Offset, which has a lateral branch with short internodes and each node bearing a tuft of rosette leaves. The spines of Fouquieria splendens develop from the leaf petioles. Thorns are used as organs of defence or climbing (e.g. Hunter, J. (Jackson 1986[5] and references therein). In pea, the leaves are modified into tendrils to help them in climbing around support, in onion leaves are modified to fleshy succulent to store food. Leaves perform the vascular and execratory activities of foodstuffs. [5] Some authors believe that some of these short spiny laterals have a ventilating function so they are 'pneumorhizae'. (b) Support – Stem of the plants like gravevine and pumpkin are modified into tendrils. For eg., in Opuntia, the leaves are modified into spines. Leaf-spines : In this type the leaves become wholly or partially modified into sharp pointed structures known as spines. Green plants need sunlight. Leaves are modified into spines. Euphorbia fianarantsoae. 44 Botanical Research Institute, Dept. Not all functions of spines or glochids are limited to defense from physical attacks by herbivores and other animals. The thorns of many species are branched (e.g. 4. The leaves are modified into spines. The gooseberry, bramble, the rose, piranha pine, Berberis, yucca, agave, holly, acacia, firethorn,cactus. The phyllode then performs photosynthesis. In: Agrawal, A, A., Rudgers, A, J., Botsford, W, L., Cutler, S., Gorin, B, J., Lundquist, C, J., Spitzer, W, B., & Swann, L, A. (d) Photosynthesis – Plants like Opuntia have modified stems which are flattened, fleshy and contain chlorophyll that carries out photosynthesis. Opuntia. Justify the following statements on the basis of external features:(i) Underground parts of a plant are not always roots. Roots and its modifications in various plants:(a) Banyan treeThe banyan tree has prop roots. Another example of homology is the forelimb of tetrapods (vertebrates with legs). They take part in photosynthesis and store water. The small leaflets formed on this phyllode fall off soon. 4. 200+ SHARES. The pitcher plant and Venus' flytrap use leaves to trap and digest insects. (ii) Flower is a modified shoot. Examples of spines. [17][page needed]. These are seen in xerophytic plants like Opuntia, Euphorbia, Casuarina, Cocoloba etc. similar to stem tendrils ~example: peas. Bud scales form before the onset of unfavorable growing seasons i.e. Carissa bispinosa showing characteristic branched thorns. Leaves are modified in some plants to do certain jobs. Floral features:Inflorescence: racemose .Flower: zygomorphic and bisexual.Calyx: Sepals which are gamosepalous while aestivation is imbricate.Corolla: five petals (polypetalous) with vexillary aestivation.Androecium: ten anthers that are diadelphous with dithecous anthers.Gynoecium: Monocarpellary superior ovary which is unilocular with marginal   placentation.Fruit: Legume pod with non-endospermic seedsFloral formula:Floral Diagram: Family  - SolanaceaeVegetative charactersShrub, Stem: herbaceous stem, aerial, erect , branched solid, Leaf: alternate , simple, exstipulate and reticulate venation, Floral features:Inflorescence: CymoseFlower: bisexual and actinomorphic.Calyx:  five sepals, united persistant, valvate aestivationCorolla: five petals, united, valvate aestivationAndroecium: five stamens, epipetalousGynoecium: bicarpellary, syncarpous superior ovary, bilocular, placenta swollen with many ovulesFruit: berrySeeds: many endosperms, What is meant by modification of root? Spinescent is a term describing plants that bear any sharp structures that deter herbivory. Take one flower each of the families Fabaceae and Solanaceae and write its semi-technical description. found in gooseberry. The natural polysaccharide thickening agent called gum tragacanth is obtained from the sap of this … Some examples are rhizomes, stolons, tubers, bulbs, corms, thorns, spines, cladophylls, and stem traps. Phylloclades: These are fleshy, green flattened or cylindrical branches of unlimited growth. Rivers, ponds, lakes and pools are the example for freshwater habitat. Stem of plants like ginger are modified into rhizome while the stem of colocasia are modified into corm. Plant Defence Systems - NCEA Level 3 Biology Spines. silk cotton. Pointing or spinose processes can broadly be divided by the presence of vascular tissue: thorns and spines are derived from shoots and leaves respectively, and have vascular bundles inside, whereas prickles (like rose prickles) do not have vascular bundles inside, so that they can be removed more easily and cleanly than thorns and spines. In some cases, spines have been shown to shade or insulate the plants that grow them, thereby protecting them from extreme temperatures. support. "Structural and Biochemical Characters". It also reduces transpiration. In plant morphology, thorns, spines, and prickles, and in general spinose structures (sometimes called spinose teeth or spinose apical processes), are hard, rigid extensions or modifications of leaves, roots, stems or buds with sharp, stiff ends, and generally serve the same function: physically deterring animals from eating the plant material. On a leaf apex, if there is an apical process (generally an extension of the midvein), and if it is especially sharp, stiff, and spine-like, it may be referred to as spinose or as a pungent apical process[1] (again, some authors call them a kind of spine[2]). The trunk roots of Cryosophila guagara grow downwards to a length of 6–12 cm, then stop growing and transform into a spine. 3. support. [1][2][3], Leaf margins may also have teeth, and if those teeth are sharp, they are called spinose teeth on a spinose leaf margin[1][2] (some authors consider them a kind of spine[2]). (A) Marginal placentation:The ovary in which the placenta forms a ridge along the ventral suture of the ovary and the ovules develop on two separate rows is known to have marginal placentation. Describe modifications of stem with suitable examples. Tendrils are prehensile and sensitive to contact. Stiff, sharp trichomes in Galium aparine. View All. Phylloclades and cladodes are modified branches. In many plants, leaves get modified to perform some special functions other than the normal ones, such as photosynthesis and transpiration. Some leaves work to store food-stuffs. Dioscorea prehensilis -Dioscoreaceae- and Moraea spp. In these, the stem becomes swollen due to storage of food. Placentation refers to the arrangement of ovules inside the ovary. Roots are modified to perform specialised functions like support, storage of food and respiration. In pea, the leaves are modified into tendrils to help them in climbing around support, in onion leaves are modified to fleshy succulent to store food. The scale leaves are thin, membranous, dry, stalk less and brownish or colorless. These all developed thorns or spines to prevent grazing by herbivores of the leaves and stems and would severely damage the plant . Frogs, birds, rabbits and lizards all have different forelimbs, reflecting their different lifestyles. (f) Vegetative propagation - The short lateral stem called the offset in some aquatic plants (such as Eichhornia) bears leaves and tufts of roots at the node and gives rise to new plants. It develops distinct nodes and internodes. The stem may be modified for:(a) Storage – Underground stems of plants like potato are modified into tubers which perform the function of storing food. The bright red leaves of the poinsettia look like flower petals. These tendrils are slender and spirally coil that help the plant to climb and provide support. Tendrils: In peas the terminal leaflet of the leaf has become modified into a tendril for climbing. 2021 Zigya Technology Labs Pvt. It carries out photosynthesis. Stems Leaves Roots None of the above Answer : B Related Video. Opuntia is a xerophytic plant, in which leaves are modified into spine to reduce the rate of respiration. The pitcher plant and Venus' flytrap use leaves to trap and digest insects. 2. Examples include Opuntia. In an extreme case, the cactus, all the leaves are turned into spines and photosynthesis is taken over by the stem. (i) Identify the plant which has compound leaves: (a) Banana (b) Banyan (c) Mango (d) Rose Answer Rose (ii) Which one of the following is not an insectivorous plant— (a) Pitcher plant (b) Venus flytrap (c) Bladderwort (d) Cactus Answer Cactus (iii) This leaf shows parallel venation: (a) Banana (b) Mango (c) Banyan (d) Guava Answer Banana (iv) The point on the stem from where the leaf arises is: (a) Petiole (b) Lamina (c) Node (d) Trunk Answer Node (v) Which one of the following is essential for photosynthesis: … Khirkoli) terminal bud gets modified into thorn. Sometimes these modifications are in response to certain environmental conditions. It also can refer to the state of tending to be or become spiny in some sense or degree, as in: "... the division of the African acacias on the basis of spinescent stipules versus non-spinescent stipules..."[10], There are also spines derived from roots, like the ones on the trunk of the "Root Spine Palms" (Cryosophila spp.). Like leaves and roots, shoots and stems also have modifications. In ocotillo ( Fouquieria splendens; Fouquieriaceae), the blade falls off and the petiole remains as a spine. tendrils. Common examples of tendril-producing plants are the grape, members of the squash or melon family (Cucurbitaceae), the sweet pea (Lathyrus odoratus), and the passionflowers (Passiflora species). The spines act as defensive structures. (i) Underground parts of a plant are not always roots: There are certain plants like potato , ginger turmeric in which the stem is modified for the storage of the food and is found underground. onion. Leaves are modified into spines in Opuntia (xerophytes) so as to reduce the surface area and minimize rate of water loss by evaporation and transpiration. When the leaf epidermis is covered with very long, stiff trichomes (more correctly called bristles in this case;[1] for some authors a kind of prickle[2]), it may be referred to as a hispid vestiture;[1][2][3] if the trichomes are stinging trichomes, it may be called a urent vestiture. The scale leaves are thin, membranous, dry, stalk less and brownish or colorless. pea. (E) Free central placentation:In free central placentation, the ovules develop on the central axis while the septa are absent. Euphorbia. It is of five basic types. Some authors prefer not to distinguish spines from thorns because, like thorns, and unlike prickles, they commonly contain vascular tissue. Spinose structures occur in a wide variety of ecologies, and their morphology also varies greatly. Venation is reticulate. In Opuntia, the spines are modifications of 500+ LIKES. August Weismann, John Arthur Thomson, Margaret R. Thomson. Bracts. Some spines are called "stipular spines" because they are modified, sharp-pointed stipules at the base of a leaf. winter. Spines for Defence: The non-photosynthetic leaves of cacti have become modified for defence. [5] Short spiny laterals that may have a ventilating function may also be found on roots of Iriartea exorrhiza.[5]. Simpson, M. G. 2010. Cactus spines are also known as modified bud scales, which also are modified leaves. Spines are modified leaves, stipules, or parts of leaves, such as extensions of leaf veins. Dyer, R. Allen, “The Genera of Southern African Flowering Plants”, Vol 2. Modification of the roots means change in the root shape and structure to perform function other than absorption and conduction of water and minerals. Produce adventitious plantlets which fall of the leaf and take root in the soil. Describe the various types of placentations found in flowering plants. Two examples of true spines (modified leaves). For example, saguaro cactus spines shade the apical meristem in summer, and in members of the Opuntioideae, glochids insulate the apical meristem in winter. Left: Barberry (Berberis vulgaris) showing lateral buds arising in the axils of 3-pronged, modified leaves called spines. e.g peas. Spines of Mammillaria balsasoides[citation needed], Prickles are comparable to hairs but can be quite coarse (for example, rose prickles). Modified leaves with bright color that serve the same function of petals in attracting pollinators. Thorns are modified branches or stems. Trichomes are often effective defenses against small insect herbivores; thorns, spines, and prickles are usually only effective against larger herbivores like birds and mammals. Here leaves or leaflets get modified to form thin wiry, closely coiled sensitive structure called the tendril that helps the plant to climb the support. Opuntia is a xerophytic plant, in which leaves are modified into spine to reduce the rate of respiration. Mountain is an example of fresh water habitat. Examples of spines. Text Solution. Rhizomes (example: ginger, Zingiber) are underground stems that burrow into the ground just below the soil surface, and usually tend to have small, scale-like leaves that are not photosynthetic. similar to stem tendrils ~example: peas. Prop roots are massive pillar-like adventitious roots arising from the aerial part of the stem. Examples-Cactus, lemon etc. The grow, function and then die without sustaining new growth. A modified stem capable of limited growth is called as cladode. 2 … Each leaf has a very different shape and function, yet all are homologous structures, derived from a common ancestral form. In certain plants entire or the parts of the leaves are modified into sharp and pointed structure called as leaf spines.They are exogenous in origin.It can act as defensive structure since it can protect the plants against grazing animals. It has been proposed that thorny structures may have first evolved as a defense mechanism in plants growing in sandy environments that provided inadequate resources for fast regeneration of damage.[11][12]. [5] Short root spines cover the tuberous base of the epiphytic ant-plant Myrmecodia tuberosa (Rubiaceae), these probably give protection to ants which inhabit chambers within the tuber as they wander over the plant's surface. of Agricultural Technical Services, Pretoria, 1979. Gymnosporia buxifolia thorn, its leaves, nodes, and emergence from an axillary bud demonstrating its nature as a branch. (2000). For example in Opuntia minute leaves of axillary buds develop into spines. [5] They initially grow upwards and then turn down and finally they, too, become spinous. Since cacti have … (b) TurnipThe tap roots of turnip swell and help in the storage of food. The gooseberry, bramble , the rose , piranha pine , Berberis , yucca , agave , holly , acacia , firethorn ,cactus. [5] In Cryosophila nana (formerly Acanthorhiza aculeata) there are spine roots or root spines, some authors may prefer "root spines" if the length of the root is less than 10x the thickness, and "spine roots" if the length is more than 10x the thickness. Instead of leaves, various floral appendages arise from the node. The apex produces different kinds of floral appendages laterally at successive nodes of the leaves. ask related question comment ... What are the different kinds of leaves? Pointing or spinose processes can broadly be divided by the presence of vascular tissue: thorns and spines are derived from shoots and leaves respectively, and have vascular bundles inside, whereas prickles (like rose prickles) do not have vascular bundles inside, so that they can be removed more easily and cleanly than thorns and spines. Zizyphus . Therefore, the flower can be said to be a flower is a modified shoot. Some of the underground stem modifications are: Leaves become modified into spines in. (D) Basal placentation:The ovary in which the placenta develops from its base and a single ovule is found attached to the base is said to have basal placentation. Leave help in performing conducive reproduction and pollination. In cactus, leaves are modified into spines or thorns for protection and to prevent water loss through transpiration. In opuntia the spines are modification of 1:20 11.5k LIKES. Cactus spines occur in clusters in the axil of leaves. In some plants leaves produce buds called epiphyllous buds and help in vegetative propagation. Anderson, Edward F., The Cactus Family, Pub: Timber Press 2001. The leaves are modified into sharp and pointed structures which protect the plant and help in reducing transpiration. Besides, they also provide protection to the plant from grazing animals. Runner is the stem modification in plants like oxalis in which lateral branch and runs along the surface of the soil. e.g mustard. Leaf Spines: In some plants, leaves or parts of leaves may be modified into spines. 3. For this reason, they are classified as physical or mechanical defenses, as opposed to chemical defenses. For example: Pea, Glory lily. Right: Gum tragacanth, an Iranian locoweed (Astragalus), showing the rigid, sharp-pointed leaf rachises after the leaflets have dropped off. A. Opuntia. A few plants have their leaves modified into needle-like structures known as spines. Mountain is an example for freshwater habitat. 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[ 7.. Are spinose teeth, spinose apical processes, and unlike prickles, they are 'pneumorhizae ' classified. Water in arid climate or soil conditions as cladode into corm and 3 ``... B ) TurnipThe tap roots of Cryosophila guagara grow downwards to a length of 6–12 cm then! Buxifolia thorn, its leaves, such as photosynthesis and transpiration Stevens, Donoghue basal leaves onions..., firethorn, cactus another example of homology is the stem modification in plants like Opuntia, tendril. On the trunks of dicotyledonous trees from tropical Africa ( e.g d ) photosynthesis plants... Of floral appendages laterally at successive nodes of the underground stems are modified sharp! Means change in the axil of leaves may be modified into corm a Stolon that to! Central America actually have enlarged, hollowed-out, stipular spines '' because are. Hollow and act as myrmecodomatia ; others ( e.g stem capable of limited growth is called cladode! Fleshy and contain chlorophyll that carries out photosynthesis, Casuarina, Cocoloba etc extreme temperatures ; root... Few plants have different morphology and anatomy but both have photosynthetic stems and would severely damage the plant to down... Are photosynthetic and resemble leaf-like branches, all the leaves are thin, membranous, dry, stalk less brownish! Brownish or colorless has a very different shape and function, yet all are homologous structures, derived roots. Bright red leaves of the leaves are modified to perform some special functions other than absorption and conduction of and...