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  1. 1. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ LONG ANSWER QUESTION1. Describe various types of aerial stem modifications. Ans: a) Tendrils b) Thorns c) Hooks d) Phylloclade e) Tuberous stem f) Bulbila) Tendrils: Wiry, coiled, sensitive structures produced by weak stemmed plants are called tendrils. Eg:- Terminal bud is modified into tendil in Vitis, axillary bud is modified in to tendril in Passiflora.b) Thorns: Hard, woody, pointed structures developed from Terminal /Axilary bud is called thorn. They give protection. Eg:- In Bougainvillea, Durantaand Punica– axillary bud is modified into thorns. In Carissa terminal bud is modified in to pair of thorns. c) Hooks: Woody curved sensitive structure formed from Axillary/ Terminal bud is called Hook. They help in climbing. In Hugonia axillary bud is modified into hook. In Artabotrys apical bud is modified into an inflorescence peduncle into a hook. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  2. 2. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵd) Phylloclade: In xerophytes the leaves are modified into scales/spines to reduce transpiration. The main stem is modified in to flattened structure to perform photosynthesis. These are called phylloclades. Eg: A) Opunita B) Cocoloba C) Casuarina.In Opuntia, all the leaves of axillary bud are modified into spines and small hair like spinescalled bards. These together called Areole.Cladophyll / cladode is a variation of phylloclade. It may have one / more internodes that areflat / cylindrical.Ex: Asparagus, Ruscus. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  3. 3. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵe) Tuberous stem: The aerial stems which store food materials and become tuberous are called tuberous stems. Eg: Brassica oleraceavar, ganyloides (knoll Kohl), Bulbophyllum In Bulbophyllum, generally one internode of the stem stores food and water and becomes tuberous. It appears as a bulb like structure and is called pseudobulb, Due to this adaptation; the plants can survive during unfavorable conditions.f) Bulbils: In some plant species the vegetative and floral buds are modified into condensed branches. They store food materials. These modified buds are called bulbils. They help in vegetative propagation. Ex: Dioscorea – Bulbils present in the axils of leaves. Agave Globba– Bulbils present in the axils of bractsOxalis - Bulbils present at the top of tuberous root.2. Describe various types of sub-aerial stem modifications? Ans: In some weak stemmed plants the stem remains partly underground. These stems are called sub-aerial stems. These are four types: a) Runners b) Stolons c) Suckers d) Offsetsa) Runners: In some weak stemmed plants the stem creeps on the soil and adventitious roots develop at every node. Whenever internodes break off, nodes lead an independent life. Ex: Oxalis, Hydrocotyl vulgaris, Lippianodiflora ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  4. 4. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵb) Stolons: In some plants the basal branches of the stem grow obliquely downwards and touch the soil. There they produce adventitious roots. These branches are called stolon. They help in vegetative propagation when they are separated from mother plant, they live as independent plants. Ex: Jasminum, Nerium.c) Suckers: In some plants a part of the stem is underground. The underground branches grow obliquely upwards from the axillary buds of nodes present below the soil. These branches produce roots on the lower surface are called suckers. Ex: Chrysanthemum, Mentha.d) Offset:These are found in free floating water plants. The stem is reduced to a disc like structure. Many leaves are developed from this stem in rosette manner. The axillary buds of these leaves develop into short, slender branches of usually one internodal length and grow horizontally above the water. These branches are called offsets. When these offsets break-off they develop into new plants. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  5. 5. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ Ex: Pistia, Eiachhornia.3. What are multipurpose stem modifications (or) Describe underground stem modifications.A) 1. The underground stems store food. 2. They help in vegetative propagation. 3. They are protected from herbivorous animals. 4. They act as organs of perennation. As they perform all these above characters they are called multipurpose stem modifications. They are of following types. 1) Rhizome 2) Corm 3) Stem tuber 4) Bulba) Rhizome: It is an underground stem which grows horizontally below the soil It contains nodes and internodes. Scale leaves are present at the nodes. It is dorsiventrally differentiated and produces aerial branches as well as reproductive organs from the dorsal side and adventitious roots from the ventral side. The branches developed from the axillary buds not only store food materials but maintain horizontal growth of the rhizome. Terminal bud develops and produces aerial branches. The underground rhizome remains alive even in drought conditions.Ex:- Zingiberofficinalis, Curcuma longa, Musa paradisiaca and Canna indica. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  6. 6. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵb) Corm: It grows vertically in soil. It bears nodes, internodes and scale leaves. Axillaary buds produce daughter corms. Terminal bud is big and produce aerial shoot.Ex: Colocasia, Amorphophallus. In Amorphophallus, special adventitious roots called pull roots keep the corm at a particular depth in soil.c) Stem tuber: The apices of underground branches that store food and become tuberous are called stem tubers. The stem tuber is covered by brown periderm. It bears many eyes that represent nodes. Each eye contains semi lunar leaf scar and an axillary bud in its axil. Eyes help in vegetative propagation. Plant name Reserve food Helianthus tuberosus inulin Stachystubifera Stachyose Solanumtuberosum Starchd) Bulb: It is special underground stem modification that does not store food materials in stem. The stem is reduced to a biconvex shaped disc like structure. It bears adventitious roots on its lower side and leaves on upper side. Leaf bases (scale leaves) store food and water. Axillary buds produce daughter bulbs and terminal bud present at the centre of the bulb develops into an aerial shoot producing inflorescence. It is two types: ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  7. 7. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ a) Tunicated bulb: The entire bulb is covered by dry membraneous scale leaves called tunic. The fleshy leaf bases overlap one above the other in concentric circles. Eg: Allium cepa.b) Scaly/ imbricate/ naked bulb: Fleshy scale leaves are arranged loosely and tunic is absent. Ex: Liliumcandidum. In Allium sativum a number of fleshy scale leaves called cloves are arranged as in scaly bulb but a group of such cloves are enclosed in a whitish, skinny tunic.SHORT ANSWER QUESTIONS1. Define phylloclade. Describe it.A) 1. The modified green, leaf like aerial stem that performs photosynthesis is called a phylloclade. 2. It is a special modification of aerial stem that performs photosynthesis. 3. It is seen in xerophytes only. 4. The leaves are modified into scales / spines. 5. The phylloclades of casuarina are needle like in cocoloba are ribbon like and in opuntia are flattened.Eg: Opuntia, Casuarina and Cocoloba. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  8. 8. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ 6. In Opuntia all the leaves of axillary bud are modified into a group of spines. A group of spines and barbs is called areole. Each areole represents a node.2. What is a stem tuber? How does it differ from tuberous stem?A) 1. Swollen, tuberous bulged apex of the underground branch that store food materials is called stem tubers. Ex: Solanum tuberosum. Stem tuber Tuberous stem 1. It is an underground stem modification 1. It is an aerial stem modification 2. It does not possess roots. 3. It is brown in colour 2. It possess roots 4. It possess eyes 3. It is usually green in colour 4. It doesn’t posses eyes Eg: Solanum tuberosum Eg: Knol - kohl3. What is a bulb? Describe various types of bulbs.A) Bulb:1. Special underground stem modification, that does not store food material in the stem is called bulb.2. The stem is reduced to a biconvex shaped disc like structure.3. It bears adventitious roots on its lower side and leaves on upper side. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  9. 9. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ4. Leaf bases are scale leaves store food, water and become flesh.5. Axillary buds produce daughter bulbs and terminal bud develops into an aerial shoot producing inflorescence. It is two types:a) Tunicated bulb: The entire bulb is covered by dry membranous scale leaves called tunic. The fleshy leaf bases overlap one above the other in concentric circles. Eg: Allium cepa.b) Scaly/ imbricate/ naked bulb: Fleshy scale leaves are arranged loosely and tunic is absent. Ex: Liliumcandidum. In Allium sativum a number of fleshy scale leaves called cloves are arranged as in scaly bulb but a group of such cloves are enclosed in a whitish, skinny tunic.4. Differentiate rhizome and corm.A) Rhizome Corm 1. It grows horizontally below the 1. It grows vertically below the soil. soil 2. It is dorsiventrally differentiated 2. It is not dorsiventrally 3. Apical bud is small. differentiated. 4. Contractile roots or pull roots 3. Apical bud is large are absent. 4. Pull roots/contractile are present. Eg: Ginger, Turmeric Eg: Amorphophallus5. Differentiate bulb and bulbil.A) Bulb Bulbil 1. It is underground stem 1. It is a aerial stem modification. modification. Stem is reduced to It is a modified vegetative or floral biconvex discoid structure. bud. 2. It does not store food materials 2. It stores food material. in the stem. The food is stored in ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  10. 10. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ leaf bases or scale leaves. 3. Daughter bulbs that develop from the axillary buds grow into 3. Bulbils detached from the new plants. parent plant develop into 4. It produces adventitious roots individual plants. on the lower side of the stem. 4. It does not bear adventitious roots still germination. Eg: Allium, Lilium Eg: Dioscorea, Agave, Globba.VERY SHORT ANSWER QUESTION1. Which underground stem modification does not possess roots? Mention its scientific name.A) Stem tuber does not possess roots. Eg. Solanumtuberosum, Helianthus tuberosus, Stachystubifera2. Which aerial stem modification is concerned with vegetative propagation? Give two examples.A) Bulbils are concerned with vegetative propagation. Eg: Dioscorea, Agave.3. What is a cladophyll? How does it differ from phylloclade?A) Cladophyll is a variation of phylloclade. It is a short green cylindrical or flattened branch of limited growth which develops from the node of the stem or branch in the axil of scale leaf. Phylloclade is a leaf like modified stem, or branch and that performs photosynthesis.4. What are scale leaves? Mention the names of any two stem modifications in which scale leaves are present.A) The leaves which are reduced to small, colourless, dry membranous structures are called scale leaves. These are present in rhizome and corm.5. Define pseudobulb. Give an example.A) Pseudobulb is a aerial stem modification which stores food and appears as a bulb like structure called Pseudobulb. Eg: Bulbophyllum.6. In which forms is the food stored in the stem tubers of Helianthus tuberosus and Stachystubifera? ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  11. 11. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵA) In Helianthus tuberosus food is stores in the form of inulin, and Stachystubifera it is stored in the form of stachyose.7. Define contractile roots, mention their function.A) Special modified, mechanical adventitious roots present in Amorphophallus are called contractile roots. They help the corm to kept at a particular depth in the soil.8. Write briefly about eye like structures present on stem tuber.A) Stem tuber bears eye like structures. Each eye represents a node. Each eye possesses a semi lunar leaf scar and an axillary bud in its axil They help in vegetative propagation. Eg.Solanumtuberosum.9. Define areole. Give an example.A) The group of barbs and spines present at every node of phylloclade of opuntia is known as areole. Eg: Opunita.10. What is the sub-aerial stem modification found in Pistia? Name any one terrestrial plant having the same type of modification.A) i) Offsets ii) Agave AmericanaQUIZ TYPE QUESTIONS1. What is the seedling material used for raising potato plants?A) Potato tubers bear many eye like structures. These ‘eye’ like structures help in vegetative propagation which are separated from the tuber and used as seeding material for raising potato plants.2. How are weak stemmed plants exposed to sunlight?A) Weak stemmed plants exposed to sunlight with the help of climbing organs such as tendrils and hooks.3. Phylloclades are found in plants growing in desert areas. Why? ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ
  12. 12. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵA) In desert plants leaves are modified into scale leaves and spines to minimize the rate of transpiration. In such plants stem modified into green leaf like structure to perform is called phylloclade.4. In Bulbophyllum, the tuberous part is called pseudobulb. Why?A) In Bulbophyllum one internode of the stem stores food and water and becomes tuberous. It looks like bulb. So that tuberous part is called pseudobulb.5. Name the modified stems having the following charactersa) Presence of adventitious roots at every node.b) Formation of adventitious roots from any part of the stem when contacted with soil.c) Initially underground but later becomes aerial.d) One internodal long branches that give rise to daughter plants.A) a) Runner b) Stolon c) Sucker e) Offset6. How are scale leaves helpful to the underground stems?A) In underground stems scale leaves protect the axillary buds and help in the storage of food and water.Important QuestionsLong Answer Questions 1. Describe various types of aerial modified stems 2. Write about underground modified stems.Short Answer Questions 1. Differentiate bulb and bulbil 2. What is stem tuber? How it is differentiated from stem tuber?Very short answer questions 1. Which underground stem modification does not possess roots? Mention its scientific name. 2. What is cladophyll? How does it differ from Phylloclade? 3. Define contractile roots. Mention their function. 4. Define areole. Give an example. 5. In which form is the food stored in stem tubers of Helianthus tuberosus and Stachystubifera. 6. What is the nature of tendrils in Passiflora, Vitis and Cissus. ǁǁǁ͘ƐĂŬƐŚŝĞĚƵĐĂƚŝŽŶ͘ĐŽŵ

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