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Morphology of Flowering Plants BY AWANTIKA.pdf

In the morphology of flowering plants, we study the external structures, which are divided into two main systems. The part below the ground is the root system, and the part above the ground is the shoot system. The shoot system consists of the stem, leaves, flowers, and fruits.

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CLASS: XI BIOLOGY MORPHOLOGY OF FLOWERING PLANTS AWANTIKA ANAND, PGT BIOLOGY DEVSANGHA NATIONAL SCHOOL, DEOGHAR JHARKHAND - 814114
MORPHOLOGY OF FLOWERING PLANTS Morphology is the study of size, shape and structure of plants, animals and microorganisms and of the relationship of their constituent parts. Radicle - It is the embryonic part which gives rise to the Root system Plumule - It is the embryonic part which gives rise to the Shoot system
PARTS OF A FLOWERING PLANT A typical flowering plant consists of a) an underground root system b) an above ground shoot system
ROOT SYSTEM The radicle of the embryo of seed gives rise to root system GENERAL CHARACTERISTICS OF ROOTS (i) Roots show no nodes and internodes (ii) They do not bear any bud (iii)They are positively geotropic & negatively phototrophic (iv) The roots are normally underground & non green FUNCTIONS OF ROOT SYSTEM (i) Roots anchor the plant to the soil (ii) They absorbs water & minerals from the soil (iii) The root tip synthesize plant growth regulates
CLASSIFICATION OF ROOT SYSTEM Root system Tap root system Fibrous root system Adventitious root system Here the radicle continues to grow as primary root & gives off branches of various orders forming a tap root system It is characteristic of dicot plants When the radicle is repeatedly branched & forms a tuft of roots from the base of the stem, it is fibrous root system It is characteristic of grasses like wheat (Monocot plants) When roots arise from any part of the other than radicle, they are called adventitious roots.
REGIONS OF THE ROOT ● Tender root apex is protected by thimble like structure called root cap. ● Just above the root cap, extending to a few mm above is the meristematic region. ● The region of elongation lies proximal to the meristematic region. ● The region of maturation lies just above the region of elongation ● A cluster of root hair arises from the epidermal cells of the region of maturation.
MODIFICATIONS OF ROOT When roots change their shape & structure to perform functions other than anchorage & absorption they are called modified roots. (I) STORAGE ROOTS Tap root modification (Eg: Carrot, Turnip, Radish etc) become swollen with stored food materials Adventitious roots (Eg : Asparagus, sweet potato etc) become swollen with stored food materials
MODIFICATIONS OF ROOT (II) PROP ROOTS Prop roots are massive pillar like out growths of aerial branches, which grow downwards & become large & woody, to support the expanding canopy of the tree. Eg : Banian (III) STILT ROOTS : These are supporting roots which arise from the basal nodes just above just above the ground. Eg : Pandanus, Maize, sugar cane etc., (iv) PNEUMATOPHORES : These are the branches of roots that grow vertically above the ground & bear openings called pneumathodes for exchange of gases. These are found in plants like Rhizophores, Which grow in marshy areas.
SHOOT SYSTEM It develops from plumule of the embryo of the seed GENERAL CHARACTERISTICS OF STEM (i) Nodes and inter nodes (ii) bear auxillary & terminal buds (iii) generally green when young & later became woody & dark brown FUNCTIONS OF STEM (i) Spreading out the branches, bears leaves, flowers & fruits (ii) It conducts water & minerals absorbed by roots to the leaves & the organic food prepared by leaves to roots & storage organ. (iii) Stem becames modified for perennation (is ability of organism particularly plants, to survive from one germination season to another especially under unfavorable conditions such as drought or winter). Vegetative propagation, protection, support & Photosynthesis
MODIFICATION OF STEM (i) Underground stems of Potato, Colocasia, Ginger, Turmeric etc are modified to store food; they also act as organs of perennation to tide over unfavourable conditions & vegetative propagation.
MODIFICATIONS OF STEM (ii) TENDRILS – Tendrils are slender & spirally coiled structures that help the weak stemmed plants to climb on to support. Eg : Cucumber, Grapevine etc., (iii) THORNS – Thorns are woody, straight, pointed structures, which develop from auxillary buds. They protect the plants from browsing animals. Eg : citrus, Bougainvillea etc (iv) When the leaves of arid plants are modified into the stem becomes thick, fleshy, green & carryout photosynthesis. Eg : Opuntia, Euphorbia
MODIFICATIONS OF STEM (v) In grasses & strawberry, the slender sub aerial stems help in vegetative reproduction vi) In Jasmine & mint, a slender lateral branch arises from the base of the main stem & help to produce a new plant. (vii) In Pistia & Eichornia, it is a lateral branch with short and thick internodes & nodes with rosette of leaves and a tuft of roots
MODIFCATION OF STEM (viii) In chrysanthemum & pineapple, it is a lateral branch of stem which originates from the basal & underground part of the main stem grows horizontally beneath the soil & comes out obliquely upward & gives rise to new leafy shoots
LEAF 🡪 Leaf is a lateral flattened structure that arises at a node from the shoot meristem. 🡪 Each leaf passes a bud in its axis known as axillary bud 🡪 A leaf has the following three parts 🡪 Leaf Base, Petiole, Lamina/Leaf Blade 1) LEAF BASE : 🡪 It attaches the leaf to the stem 🡪 In monocot plants, the leaf base expands into a sheath like structure & in dicots it may bear stipules 🡪 In members of bean family, the leaf base is swollen (Pulvinus) & helps in sleep movement. 2) PETIOLE : The stalk of the leaf 3) LAMINA / LEAF BLADE 🡪 Green expanded part of the leaf, which is main seat of Photosynthesis 🡪 It is supported by veins & vein lets, there is usually a middle prominent vein, caked the mid rib
LEAF VENATION The arrangement of veins & vein lets in the lamina is known as venation. Veins and vein lets (a) Provide rigidity & support to the blade. (b) They are channels of transport of water, minerals and food materials. TYPES OF VENATION RETICULATE VENATION PARALLEL VENATION Network arrangement on lamina Eg : Dicot leaf Veins on the lamina run parallel to one another Eg : Monocot leaf
TYPES OF LEAVES Based on the incision of the lamina leaves are classified into Simple & compound leaves (a) Simple leaves – Lamina is entire or when incised, the incisors do not rundown to the midrib. Ex : Mango, China rose (b) Compound leaves – When its lamina is incised down to the midrib, into number of segments, called leaflets, each with a very short stalk. Ex : Rose, Neem A leaf has a bud in its axil, but a leaflet does not have it.
PHYLLOTAXY The arrangement of leaves on a stem or axis. TYPES OF PHYLLOTAXY ALTERNATE OPPOSITE WHORLED A single leaf arises at each node in an alternate manner. Examples: China rose, Sun flower A pair of leaves arise at each node and lie opposite to each other. Examples: Calotropis, Guava More than two leaves arise at a node and form a whorl. Example: Alstonia
INFLORESCENCE The mode of arrangement of flowers on a floral axis (Peduncle – a stalk supporting on inflorescence) TYPES OF INFLORESCENCE Racemose Inflorescence Cymose Inflorescence • Pedundle shows indefinite growtn • Usually Penduncle do not ends in a flower • Older flowers are at the base & younger flower at the top • Development of the flowers is an acropetal succession • The order of opening flowers is centripetal i.e. from the periphery towards the centre Ex : Caesalpinea • Penduncle shows definite growth • Penduncle ends in a flower • Older flowers at the apex & younger flower at the base • Development of flowers is basipetal succession • The order of opening of flower is centrifugal Ex – Jasmine, Hibiscus
FLOWER ➢ Reproductive part ➢ Modified shoot with much condensed inter node & a number of appendages (floral leaves) at a node. ➢ Stalk of the flower – Pedicel ➢ Calyx & corolla - Non essential whorls ➢ Androecium & Gynoecium are reproductive whorls
SYMMETRY OF FLOWER Actinomorphic (Radial symmetry) Zygomorphic (Bilateral symmetry) Asymmetric (irregular) When a flower can be divided into 2 equal radial halves in any radial plane passing through the center Ex : Mustard, Datura, Chilly When it can be divided into 2 similar halves only in one particular plane. Ex : Pea, Gulmohur, Bean, Cassia It cannot be divided into 2 similar halves by any vertical planes passing through the center. Ex : Canna
FLORAL APPENDAGES Trimerous Tetramerous Pentamerous Having flower parts, such as petals, sepals, and stamens, in sets of three. Eg : Daffodils, Orchids, Lilies Are those flowers that exhibit sepals, stamens, petals all in sets of four. Eg : Crucifer, members of Brassicaceae Those flowers that exhibit sepals, stamens and petals all in sets of five. Eg : petunias China rose and solanum.
Hypogynous Perigynous Epigynous Gynoecium occupies highest position. While other parts are situated below it. The ovary in such flower is superior. Eg : Mustard, China rose, Brinjal If Gynoecium in the center and the other part of the flower are located on the rim of the Thalamus almost at the same level. The ovary is half inferior Eg : plum, rose, peach The margin of thalamus grows upward enclosing the ovary completely getting fused with it. Other parts of flower arise above the ovary. The ovary is inferior. Eg : Guava, cucumber, ray florets of sun flower POSITION OF FLORAL PARTS ON THE THALAMUS Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, flowers are described as
PARTS OF A FLOWER (NON ESSENTIAL WHORLS) Calyx Corolla Outermost whorls, sepals, protect the flower during bud condition. Gamosepalous – fused sepals Polysepalous – sepals free Petals Brightly coloured attract insects for pollination. Gamopetalous – petals are fused Polypetalous – petals free PARTS OF A FLOWER Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, flowers are described as fused sepals free sepals fused petals free petals
TYPES OF AESTIVATION Valvate Twisted Imbricate Vexillary Margins of sepals / petals just touch one another & there is no overlapping Ex: Corolla of calotropis Overlaps the margin of the next Ex : Corolla of Hibiscus Posterior sepal / petal is completely internal One sepal / petal completely external Other 3 overlapped Ex : Corolla of cassia, Gulmohur (Descendingly imbricate) Ex: Papilionaceous Corolla AESTIVATION The arrangement of sepals or petals in relation to one another in the bud conditions.
Adelphy – Union or attachment of stamens Monoadelphous Diadelphous Polyadelphous Filaments are united to form one bundle, but the anthers are free Ex : Hibiscus Filaments are united to form two bundles & anthers remain free Ex : Pea, Bean In few plants, filaments are united to form more than two bundles & anthers remain free Ex : Silk cotton, Lemon, Castor ANDROECIUM Male reproductive structure, consists of stamens or microsporophyll. Anther contains pollen sacs or microsporangia in which numerous microspores or pollen grains are present.
TYPES OF OVARY BASED ON NUMBER OF CARPELS Monocarpellory Bicarpellary Polycarpelloary The ovary which has only one carpel Ex – Bean two carpels Ex – Sunflower, Tridax more than two carpels i.e. 3. Tri carpellary 4. Tetra carpellary 5. Pentacarpellary 6. Polycarpellary Ex – Lemon GYNOECIUM Female reproductive part made up of one or more carpels Pistil composed of one or more carpels (megasporophylls)
Syncarpous ovary Apocarpous Ovary Carpels are fused Ex – Hibiscus, Mustard, Tomato, Datura, Papavar Carpels are free Ex – Micheliachampaka, Rose, Lotus GYNOECIUM
PLACENTATION Placenta is a cushion like tissue on which the ovules are attached. The mode of attachment of ovules on the placenta is called Placentation. TYPES PLACENTATION 1. Marginal placentation – The placenta forms a ridge along the ventral suture of the ovary and the ovules borne on the ridge forming two rows Ex – pea, Beans 2. Axile placentation – The ovules are attached to it in a multilocular ovary. Ex – China rose, Tomato, Lemon, ladies finger
3. Parietal placentation : Ovules develop on the inner wall the ovary or on peripheral part Ex ; Papaya Ovary is one chambered but it becomes two chambered due to the formation of the false septum Ex : Mustard, Argemone 4. Free central Placentation : The ovules are borne on central axis and septa are absent Ex – Dianthus, Primrose 5. Basal Placentation : The placenta develops at the base of the ovary & a single ovule is attached to it Ex – Sun flower, Marigold
FRUITS Botanically a fruit is a mature or ripened ovary developed after fertilization If a fruit is formed without fertilization of the ovary, it is called a parthenocarpic fruit The wall of the true fruit is called pericarp PERICARP : May be dry or fleshy. When pericarp is thick and fleshy it is differentiated into outer epicarp, middle mesocarp and inner endocarp. PARTS OF A FRUIT MANGO COCONUT
SEED STRUCTURE OF DICOTYEDONOUS : A fertilized ovule develops into a seed A seed contains two parts A seed coat & an embryo outer layer - Testa Seed coat Inner layer - tegmen Embryo – Consists of embryonal axis with radicle & plumule at opposite ends. 🡪 A seed which contains endosperm is an endospermic seed Ex ; castor, coconut 🡪 A seed which does not contains an endosperm is called a non endospermous seed & such seed stores the food materials in the cotyledon(s) Ex : Bean pea mustard (Dicot), Orchids – (Monocot) 🡪 A seed with two cotyledons – dicotyledonous seed Ex : Mustard, Bean, Pea 🡪 A seed with one cotyledon – Monocotyledonous seed Ex : Coconut, Orchids etc.,
SEED STRUCTURE OF A MONOCOTYEDONOUS SEED :
SEMI TECHNICAL DESCRIPTION OF A TYPICAL FLOWERING PLANT
DESCRIPTION OF THE FAMILY FABACEAE VEGETATIVE CHARACTERS Trees, shrubs, herbs; root with root nodules Stem : erect or climber Leaves : alternate, pinnately compound or simple; leaf base, pulvinate; stipulate; venation reticulate. Pisum sativum (Pea plant)
DESCRIPTION OF THE FAMILY FABACEAE FLORAL CHARACTERS Inflorescence : racemose Flower : bisexual, zygomorphic Calyx : sepals five, gamosepalous; valvate/imbricate aestivation Corolla : petals five, polypetalous, papilionaceous, consisting of a posterior standard, two lateral wings, two anterior ones forming a keel (enclosing stamens and pistil), vexillary aestivation Androecium : ten, diadelphous, anther dithecous Gynoecium : ovary superior, mono carpellary, unilocular with many ovules, style single Fruit : legume; seed: one to many, non-endospermic Floral Formula : Economic importance : Many plants belonging to the family are sources of pulses (gram, arhar, sem, moong, soyabean; edible oil (soyabean, groundnut); dye (Indigofera); fibres (sunhemp); fodder (Sesbania, Trifolium), ornamentals (lupin, sweet pea); medicine (muliathi).
DESCRIPTION OF THE FAMILY SOLANACEAE VEGETATIVE CHARACTERS Plants mostly herbs, shrubs and rarely small trees Stem : herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous, underground stem in potato (Solanum tuberosum) Leaves : alternate, simple, rarely pinnately compound, exstipulate; venation reticulate. Solanum nigrum (makoi) plant
DESCRIPTION OF THE FAMILY SOLANACEAE FLORAL CHARACTERS Inflorescence : Solitary, axillary or cymose as in Solanum Flower :bisexual, actinomorphic Calyx : sepals five, united, persistent, valvate aestivation Corolla : petals five, united; valvate aestivation Androecium : stamens five, epipetalous Gynoecium : : bicarpellary, syncarpous; ovary superior, bilocular, placenta swollen with many ovules Fruit : berry or capsule Seed: many, endospermous Floral Formula : Economic importance : Many plants belonging to this family are source of food (tomato, brinjal, potato), spice (chilli); medicine (belladonna, ashwagandha); fumigatory (tobacco); ornamentals (petunia)
DESCRIPTION OF THE FAMILY LILIACEAE
DESCRIPTION OF THE FAMILY LILIACEAE Commonly called the ‘Lily family’ is a characteristic representative of monocotyledonous plants. It is distributed world wide. VEGETATIVE CHARACTERS Perennial herbs with underground bulbs/corms/ rhizomes Leaves : mostly basal, alternate, linear, exstipulate with parallel venation FLORAL CHARACTERS Inflorescence : solitary / cymose; often umbellate clusters Flower : bisexual; actinomorphic Perianth: tepal six (3+3), often united into tube; valvate aestivation Androecium : stamen six, 3+3, epitepalous Gynoecium : : tricarpellary, syncarpous, ovary superior, trilocular with many ovules; axile placentation Fruit : capsule, rarely berry Seed: endospermous Floral Formula : Economic importance : Many plants belonging to this family are good ornamentals (tulip, Gloriosa), source of medicine (Aloe), vegetables (Asparagus), and colchicine (Colchicum autumnale).
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