CRP 201: PLANT MORPHOLOGY – LECTURE NOTE 1

0
13

CRP 201: INTRODUCTION TO AGRICULTURAL BOTANY II

LECTURE NOTE 1

PLANT MORPHOLOGY

INTRODUCTION

Morphology – (Morphe = form + logos = study). It deals with the study of forms and features of different plant organs like roots, stems, leaves, flowers, seeds, fruits etc. The body of a typical angiospermic plant is differentiated into :

✧ an underground root system

✧ an aerial shoot system.

The shoot system consists of stem (including branches), leaves, flowers and fruits. The roots, stems and leaves are vegetative parts, while flowers constitute the reproductive part.

CLASSIFICATION OF PLANTS

Depending upon their life span, plants are classified as:

Annuals –Complete their life cycle in one year or single growing season or few weeks to a few months. They pass the unfavourable period in the form of seeds e.g. Mustard, Pea.

Biennials –Complete their life cycle in two years-growing, vegetative and storing food in the first year, flowering and fruiting in the second year. They die off after producing flowers and fruits eg. Radish, turnip, carrot are biennial in colder areas. They become annual in warmer places.

Perennials – Survives for several years. These plants usually bear flowers and fruits every year and do not die after producing flowers. E.g. Mango, Banana, Guava

Radicle comes out/arise from the seed coat in the form of soft structure and move toward the soil. It develops and forms primary root.

ROOTS

General Characteristics :

Roots are non green, underground, (+) geotropic, (–) phototropic and (+) hydrotropic.

Roots do not bear buds.

Buds present for vegetative propagation in sweet potato (Ipomea) and Indian red wood (Dalbergia) Roots do not bear nodes and internodes.

Roots have unicellularroot hairs.

  • TYPES OF ROOTS

Roots are of two types :

✧Tap root ✧Adventitious root

Tap root :It develops from radicle and made up of onemain branch and other sub branches. The primary roots and its branches constitute tap root system. e.g. Dicot roots.

Adventitious roots :In some plants, after sometime of the growth of tap root which arises from radicle, stops and then roots, develop from other part of plant, which are branched or unbranched, fibrous or storage, are known as adventitious roots and constitutefibrous root system. e.g. Monocot roots.

  • REGIONS OF ROOTS

Morphologically four distinct regions are present in roots.

Root cap: It is terminal structure. It protects tender apex of root.

Meristematic zone: Cells of this regions are very small and thin walled. They divide repeatedly and increase cell number

Elongation region: The cells proximal to meristematic zone undergo rapid elongation and enlargement and are responsible for rapid growth of roots.

Maturation region: Cells proximal to region of elongation gradually differentiate and mature. Root hairs are present in maturation zone.

  • MODIFICATION OF ROOTS
  1. Modified tap root for storage :

Fusiform roots : These root are thicker in the middle and tappered on both ends. In this type of roots both hypocotyl and root help in storage of food. e.g. Radish.

Conical roots : These roots are thicker at their upper side and tapering at basal end. e.g. Carrot.

Napiform: These roots become swollen and spherical at upper end and tapered like a thread at their lower end. eg. Turnip (Brassica rapa), Sugarbeet

Tuberous root: Such roots do not have regular shape and get swollen & fleshy at any portion of roots. eg. Mirabilis.

  1. Nodulated root : Nodules are formed on branches of roots by nitrogen fixing bacteria, (Rhizobium). eg. Plants of leguminosae family (Papilionatae) – Pea.

  1. Respiratory roots: Halophyte or mangrove grows in oxygen deficient marshy area. Some branches of tap root in these plants grow vertically & comes out from soil. These roots are called pneumatophores through which air entered inside the plant. eg. Rhizophora, Heritiera, Sonaratia and other mangrove plants.

Modification of adventitious roots :

  1. Storage adventitious roots

Tuberous root : When food is stored in these roots, theybecome swollen and form a bunch. eg.

Sweet potato (Ipomea batata)

Fasciculated – Roots arise in bunch(cluster) from lower node of the stem and become fleshy eg. Dahlia, Asparagus.

Nodulose: In this type, tips of roots swell up. eg. Melilotus, Curcuma amoda.

Beaded or moniliform : When root swells up like a bead at different places after a regular interval. eg. Vitis, Momordica(Bitter gourd), Portulaca.

Annulated : Roots having series of ring like swellings eg. Psychrotia

  1. Stilt roots or brace roots : When root arises from lower nodes and enter in soil obliquely, known as stilt roots eg. Maize, Sugarcane, Pandanus (screwpine)
  2. Prop root or pillar roots: when root arises from branches of plant and grows downward towards soil. It function as supporting stem for the plant. eg. Banyan.
  3. Butteress root – Such roots appear from the basal part of stem and spread in different directions in the soil. eg. Ficus, Bombax , Terminalia. It is a characteristic feature of tropical rain forest.
  4. Climbing roots – These roots arise from nodes and helps the plant in climbing. eg. Money plant (Pothos), Betel, Black pepper, Techoma.
  5. Foliar roots or Epiphyllous roots – When roots arise from leaf they are called as foliar roots. eg. Bryophyllum, Bignonia.
  6. Sucking or haustorial roots or Parasitic roots : In parasitic plant roots enter in the stem of host plant to absorbed nutrition from host. eg. Dendrophthoe, Cuscuta, Viscum

  1. Assimilatory roots : The aerial roots of Tinosporaand submerged roots of Trapa(Water chestnut) become green and synthesize food. Podostemonalso has green assimilatory roots.
  2. Hygroscopic roots : These are found in epiphytes, specially in orchids and help in absorption of moisture from the atmosphere using special tissue called velamen. eg. Orchids, Banda
  3. Contractile roots : They shrink 60 – 70% of the original length and bring underground organ at proper depth in the soil e.g., corm of Crocus(saffron), Fresia.
  4. Root thorns : These are hard, thick and pointed thorns e.g. Pothos armatus.

Reproductive roots : These are fleshy, adventitious roots used for vegetative reproduction e.g., sweet potato (Ipomea batata), Dahlia.

Leaf roots : In Salvinia, one leaf of each node modifies intoroot like structure for balancing the plant in water.

 

FUNCTIONS OF ROOT

  • Fixation (Primary function)
  • Absorption of water and minerals
  • Storage of food
  • Conduction of water
  • Photosynthesis and respiration

STEM

Stem is the vegetative part of plant that is seen above surface of soil i.e. it shows negative geotropic growth and which may be erect or creeping in nature. It has nodes and internodes. Branches, leaf, flower bud and bracts are developed from nodes. Stem arises from plumule.

  • FORMS OF STEM

Caudex: It is unbranched, erect, cylindrical stout stem and marked with scars of fallen leaves. Crown of leaves are present at the top of plant. eg.: Palm

Culm: Stem is jointed with solid nodes & hollow internodes. eg. Bamboo (Graminae). Excurrent :The branches arise from the main stem in acropetal succession and the tree assumes a cone like appearance e.g. Pinus, Eucalyptus, Casuarina,etc.

Decurrent (Deliquescent) :The lateral branches grow more vigorously and outcompetes the main trunk, giving a dome-shaped appearance, e.g., mango (Mangifera indica), Shishem (Dalbergia sissoo) and banyan (Ficus bengalensis).

 

  • TYPES & MODIFICATION OF STEM

Aerial stems (Epiterranean stem) :

It may be reduced, erect and weak.

Reduced – Stem reduced to a disc. eg., Radish, Carrot, Turnip.

Erect stem – It is strong and upright e.g., maize, wheat, mango.

Weak stems –These are thin, soft and weak and need support. They can be upright or prostrate.

✧ Creepers – The stem creeps on earth and the roots arise at the nodes, e.g., Grasses, Strawberry, Oxalis.

✧Traliers – The stem creeps on the ground, but the roots donot arise at the nodes. They may be of two types :

Prostrate or procumbent– The stem creeps on ground totally, e.g., Evolvulus, Tribulus.

Decumbent – When prostrate stem projects its tip, e.g., Portulaca, Linderbergia.

✧Lianas (Stem climber). Woody perennial climbers found in tropical rain forests are lianas.

They twin themselves around tall trees to secure sunlight, e.g., Hiptage, Bauhinia vahlii(Phanera).

✧Climbers – Plants are with long weak stem and have organs of attachment to climb the object. They may be of following type .

Rootlet climbers – Roots produced at nodes help in climbing e.g., Tecoma, Pothos, Piper betal(pan).

Hook climbers – In Bougainvillea, Durantaand Carrisa, the thron is modification of axillary vegetative bud which helps in climbing. In Bignonia, terminal leaflet is converted into hook.

Tendril climbers – Tendrils are thread like structure which help the plants in climbing.

✧Twiners – The stem body twines around the support without any special organ of attachment. e.g., Cuscuta, Dolichos.

 

Sub-aerial modification :

Runner – When stem grows and spread on the surface of soil. Roots are developed at lower side and leaves from upper side from node eg. Cynodon dactylon(Doob grass), Oxalis.

Stolon – In it branches are small and stem condensed and grow in all direction. After sometime, of growing, their apical region comes out from the soil. eg. Fragaria(Wild strawberry), Jasmine Peppermint.

Sucker – In it the main stem grow in the soil horizontally and branches develop obliquely from nodes above the soil, eg. Mint, Pineapple, Chrysanthemum.

Offset A lateral branch with short internode and each node bearing a rossette of leaves and tuft of roots at base. eg. Pistia, Eichhornea.

These modification are also involved in vegetative reproduction.

Underground modification :

This type of modification occurs generally for food storage and vegetative propagation.

Tuber – The tips of underground branches become swollen in the soil. Eyes are found on then which are axillary buds and covered with scaly leaves. eg. Potato, Helianthus tuberosus.

Rhizome – It is fleshy and horizontally stem found below in soil. Small nodes and internodes are found which are covered by scaly leaves. eg. Ginger, Turmeric, Canna, Water lily, Banana.

Corm – It is condensed structure which grow vertically under the soil surface. They are having spherical node and inter node eg. Colocasia, Alocasia, Zaminkand, Saffron, Gladiolus, Colchicum

Bulb– This stem is reduced and has disc like structure and surrounds with numerous fleshly scaly leaves. Many roots arise from its base. Food is stored in flashy leaves. They show apical growth eg. Onion, Garlic.

Special stem modification :

Phylloclade – It is green photosynthetic flattened or rounded succulent stem with leaves either feebly developed or modified into spines e.g., Opuntia, Casuarina, Euphorbia, Cactus.

Thorn – It is modification of axillary bud, e.g., Bougainvillea, Duranta, Carissa.Thorns of Alhagi possess flowers, while thorns of Duranta bears leaves.

Cladode – Phylloclade usually having one or two internode long & succulent is called cladode, e.g., Asparagus, Ruscus.

 

Stem tendrill– it is a leafless, spirally coiled structure found in climbers. It may be a modification of Axillary bud, e.g. Passiflora or terminal bud e.g., Vitis.

Bulbils – A condensed , axillary fleshy bud is called bulbils. It helps in vegetative reproduction. eg., Dioscorea, Globba, Agave, Oxalis.

FUNCTIONS OF STEM

The main function of the stem is spreading out branches bearing leaves, flowers and fruits. It conducts water, minerals and photosynthates. Some stems perform the function of storage of food, support, protection and of vegetative propagation.

LEAF (PHYLLOPODIUM)

The leaf is a lateral generally flattened structure borne on the stem. The leaves develop from the nodes. Their main function is photosynthesis and food making, axillary buds are found in its axil. All the leaves of a plant is known as phyllome. Axillary bud later develops into a branch. Leaves originated from shoot apical meristem and are arranged in acropetal order.

 

Leaf is divided into 3 main parts :

Leaf base (Hypopodium)

✧ Leaves are attached to stem by leaf base.

✧In some plants, leaf base becomes swollen and is called pulvinuswhich is responsible for sleep movement e.g., Cassia, mimosa, bean.

✧In some plants, leaf base expands into sheath(Sheathing leaf base), e.g., grasses and banana (monocots).

✧ When the leaf base partially encloses the stem, it is called semi amplexicaule.g., Prickly poppy, Calotropis procera(Madar).

✧ It completely encloses the stem, it is called amplexicaule.g., Sonchus, Polygonum.

Petiole (Mesopodium) – The part of leaf connecting the lamina with the branch of stem. Petiole help to hold the blade to light.

✧In Eichhorniapetiole swell and in citrus it is winged.

✧Petiole is modified in tendrils in Nepenthes.

✧In Australian acacia petiole is modified in phyllode.

✧Long thin flexible petiole allow leaf blade to flutter in air, thereby cooling the leaf and bringing fresh air to leaf.

Lamina (Epipodium) – It is a broad and flattened part of leaf. Its main functions are photosynthesis and transpiration. Shape of lamina are :

Acicular – Lamina is long and pointed, like a needle. eg. Pinus

Lanceolate – In this type lamina is pointed or narrower at the ends while broader in the middle. eg. Bamboo, Nerium

Linear – The lamina is long and narrow having parallel margins. eg. Grass

Ovate – In this type lamina is egg-shaped having broad base with slight narrow top. eg. Ocimum, Banyan, China rose.

Cordate – Its shape is like a heart. eg. Betel.

Oblong – Long and broad lamina. eg. Banana

Sagittate – The lamina is triangular in shape. eg. Sagittaria

Spathulate – The lamina is broad spoon shaped. eg. Calendula

Orbicular or Rotund – In this types the lamina is spherical. eg. Lotus.

Elliptical or Oval – In this type the middle part of laminais broad while the ends are narrow and oval. eg. Guava.

Oblique – In this types midrib divides, lamina into two unequal halves. eg. Bignonia, Neem.

Stipules :

Leaves of some plants have lateral appendages on eitherside of leaf base, known as stipules. If stipules are present in leaf it is called stipulated leaf, if it is absent then leaf is called exstipulated.

Stipules are of various types –

Free lateral – They are independently present on both sides of leaf base. eg. Hibiscus rosasinensis (China rose).

Interpetioler –When two leaves are meet oppositely at the node then nearest stipules of each leaf join with each other. In this way only two stipules of two leaves are found in place of four. eg. Ixora, Anthocephalus.

Intrapetioler – In this type both stipules of a single leaf join with each other to form a single stipule. eg. Gardenia.

Foliaceous– These type of stipules form a leaf like structure. eg. Pea

 

Scaly – Stipules are dry, small and paper like. eg. Desmodium.

Spiny –Stipules modified into spine. eg. Zizyphus(Beri), Acacia.

Ochreate –When both stipules of leaf combine together and form a tube like structure, It is called ochreate. eg. Polygonum.

Adnate– Both stipules are attached with petiole. eg. Rose.

Tendrillar – Stipules are modified into tendrils like structure. eg. Smilax.

Bud scale –Protect the young Bud. e.g. Ficus.

FORMS OF LEAF

Foliage leaf – They are usually green coloured and their main function is photosynthesis.

Cotyledonary leaf –This leaf comes out during germination and helps in nutrition until the first leaf is not formed.

Scaly leaf (Cataphylls) – Such leaves are usually dry membrane like and they can not perform photosynthesis.

Bract (Hypsophyll)– Bract are the leaves which is present in flower axis.

Bracteole – These are leaf like structure found on pedical.

Floral leaf – Sepals, petals, stamen and carpel are found in flower which are included in this type of leaf.

Perianth –In some flowers, Calyx and Corolla are not distinct and are termed as Perianth and unit of perianth is called tepal. eg. Lily.

Duration of leaf :

Persistent / Evergreen – Leaves of such plants are found in all season and do not (fall) shed combindly. eg. Pinus, Saraca indica, Datepalm.

Deciduous –All leaves of such plants shed at the same time eg. Azadirachta.

Caducous –Leaves fall soon just after appearance or after opening of bud. eg. Rose.

VENATION OF LAMINA

The arrangement of veins and veinlets in leaves (Lamina) is known as venation. It is of 2 types.

Reticulate :It is found in dicots. Exception – Calophyllum, Eryngium. It has parallel venation.

Parallel :It is found in monocots. Exception – Smilax,Dioscorea, Alocasia, Colocasia. It has reticulate venation.

Reticulate venation :

In it main vein divided into various branches (veinlets)and form a net like structure. Reticulate venation is of 2-types.

Unicostate or pinnate – In this type of venation leaf have only one principal vein or midrib that give off many lateral veins which proceed toward margin and apex of lamina of the leaf and form a network. eg. Mango, guava, Peepal,

Multicostate or palmate – In this type of venation many principal veins arising from the tip of petiole and proceed towards tip of lamina. This is again two types –

Multicostate divergent – Many principal veins arising from the tip of petiole, diverge from the another toward the margin of leaf blade eg. Cotton, Caster, Cucurbita, grape. ✧ Multicostate convergent – Many principal veins arising from the tip of petiole. At the base of leaf they are closely arranged but diverage from one another in middle part and converge towards the apex of leaf. eg. Camphor, Zizyphus, Tejpat, Chinarose, plum

 

Parallel v enation :

In this type of venation, all veins run parallel to each other and they do not from network. They are of 2 types.

  • Unicostate or pinnate – This type of pattern having only one principal vein, that gives off many lateral veins, which proceed toward the margin of leaf blade in a parallel manner but they donot have veinlets. eg. Banana, Ginger, Canna.
  • Multicostate or palmate – Having many principal veins arising from the tip of the petiole and proceeding upwards.

Multicostate divergent – Many principal veins arising from the tip of petiole and diverge toward the margin of leaf. They donot divide into veinlets and do not form network. eg.

Coconut, Date palm

Multicostate convergent – Many principal veins arising from the tip of petiole run in a curved manner in lamina and converge towards the apex of leaf blades. eg. – Wheat, Sugarcane, Bamboo.

  • Furcate venation – The veins branch dichotomously but the reticulum is not formed by the finer branches. eg. Adiantum (fern)

TYPES OF LEAF

Simple and Compound Leaf :

  • Simple Leaf – A leaf which may be incised to any depth, but not down to the midrib or petiole, then this type of leaf called simple leaf. eg. Mango, Chinarose, Ficus, etc.
  • Compound leaf – A leaf in which the leaf blade is incised up to the midrib or petiole, thus dividing it into several small parts, known as leaflets. This type of leaf is known as compound leaf. It is of two types

Pinnately compound leaf – In this type of leaf mid rib is known as rachis. Leaflets are arranged on both sides of rachis. eg. Neem.

It is of following types –

Unipinnate – In this type of leaf, division occurs only once and leaflets are directly attached on both sides of rachis.

✧ If the number of leaflet is even, then leaf is known as paripinnate. eg. Cassia fistula, Sesbania ✧ If the number of leaflet is odd, it is known as imparipinnate. eg. Rose, Neem. Bipinnate – A twice pinnate compound leaf eg. Acacia, Gulmohar, Mimosa.

Tripinnate – A thrice pinnate compound leaf eg. Moringa.

Decompound – A compound leaf, which is more than thrice pinnate. eg. Carrot, Coriander.

 

Palmate compound leaf – In this type incision of leaf are directed from leaf margin to apex of petiole and all leaflets are attached on the upper end of petiole.

It is of following types –

Unifoliate – When single leaflet is found. eg. Lemon

Bifoliate – When two leaflets are present. eg. Bauhinia, Regnelidium, Bignonia.

Trifoliate – When three leaflets are attached. eg. Oxalis, Aegle, Trifolium Tetrafoliate – When four leaflets are attached to the petiole. eg. Marsilea.

Multifoliate – when more than four leaflet are found, then leaf is called multifoliate palmate compound leaf. eg. Silkcotton.

Phyllotaxy :

It is of following type –

Alternate or spiral – Single leaf arising at each node. eg. Cyprus rotandus, Chinarose, mustard & Sunflower,

Opposite – Leaves occuring in pairs at the node, they may be –

Decussate : Leaves that stands at right angle to next upper or lower pair eg. Calotropis, Mussaenda. ✧ Superposed : Successive pairs of leaves stand directly over a pair in the same plane eg. Psidium (guava), Ixora.

Whorled – More than two leaves at each node eg. Nerium, Alstonia

 

MODIFICATION OF LEAVES

Leaf tendril – In it, whole leaf is modified into thin thread like structure which is called leaf tendril eg. Lathyrus aphaca (wild pea).

Leaflet tendril – When leaflet is modified into tendril like structure than it is called leaflet tendril.eg. Pisum sativum (Garden pea), Lathyrus odoratus (sweet pea).

Leaf spine – Leaves or any part of leaflet are modified into pointed spine. eg. Asparagus, Opuntia, Aloe, Argemone.

Leaf scale – In it, leaves become thin, dry and form a membrane or paper like structure and serve to protect axillary buds as in Ficus and Tamarix, Ruscus, Casurina.

Leaf pitcher – Leaves of some plants are modified to pitcher shape. eg. Nepenthes, Dischidia. Leaf bladder – In some plant , leaves are modified into bladder like structure eg. Utricularia. Leaf Hooks – In some plants terminal leaflets are modified into curved hooks for helping the plant in climbing. eg. Argemone, Opuntia, Aloe, Cat’s nail (Bignonia unguis – cati).

INFLORESCENCE

Arrangement of flower on floral axis is called inflorescence.

Racemose – In this type of inflorescence the main axis continues to grow and does not terminate in a flower and give off flower laterally in acropetal manner where old flowers are arranged toward base and young flowers are at tip. When peduncle is broad then flowers are centripetally arranged.

This is of following different types :

Raceme – When peduncle (main axis) is elongated and flowers are pedicellate. eg. Radish, characteristic feature of cruciferae family When peduncle is branched and each branch bear pedicellated flowers like racemose and are arranged in acropetal manner known as compound raceme or panicle. eg. Gulmohar, Neem.

Spike – In it peduncle is elongated but flowers are bisexual and sessile. eg. Achyranthes When peduncle is branched and each branch bear spike, like inflorescence then the small branch having flower is called spikelet and this arrangement is called as spike of spikelet. Characteristic inflorescence of family gramineae.

Catkin – In it peduncle is thin, long and weak, and flowers are sessile and unisexual. Peduncle is pendulus. eg. mulberry, betula, oak.

Spadix – In it peduncle is thick, long and fleshy and have small sessile and unisexual male and female flowers covered with one or more green or colourfull bracts known as spathe. eg. Colocasia, Maize, Aroids, Palms.

Corymb – In it peduncle is short and all flowers are present at same level because the lower flower has much long pedicel than the upper one eg. Candytuft (Iberis amara).

If in this type of inflorescene peduncle is branched, then each branch has flower cluster then this type of inflorescence is called compound corymb. eg. Cauliflower,

  • In mustard corymbose raceme type of inflorescence is present

Umbel – An inflorescence in which the flower stalks of different flowers are of more or less equal length, arise from the same point. At the base of flowers stalks, there is whorl of bracts forming the involucre. eg. Centella

If in this type of inflorescence, peduncle is branched then each branch has flower cluster then this type of inflorescence is called compound umbel. eg. Coriander, Foeniculum, Cuminum.

Characteristic feature of umbeliferae.

  • Scapigerous umbel is found in onion

Capitulum / Racemose head – In it the growth of peduncle is retarded and it become broad, flattened concave or convex. On it small flowers are found. These flowers are called floret. If all the flower of capitulum are same , then it is called homogamous. If two different type of floret, ray floret and disc floret are present in same inflorescence than it is known as heterogamous. In this type of inflorescence florets may be unisexual, bisexual and sterile. This inflorescence is surrounded by one or more involucre. It is most advanced type of inflorescence. eg. Sunflower, Zinnia, Marigold, Cosmos.

Characteristic feature of asteraceae family

 

In this type of inflorescence, the peduncle terminate in a flower. In it the older flowers are present at tip and young buds are arranged towards base. This arrangement is called basipetal succession.

 

It is of following types.

Uniparous cyme / Monochasial cyme – The peduncle ending in a flower producing lateral branch at a time of ending in flower. It is of two types –

Helicoid cyme – When all lateral branches developed on the same side on peduncle then it is called helicoid cyme. eg. Heliotropium, Saraca, Atropa, Datura.

Scorpioid cyme – In it the lateral branch is alternately develop on left and right side. eg.

Bignonia,

Riphidium – In monochasial cyme all flowers are borne on same plane. eg. Solanum nigrum

Dichasial or biparous cyme – In it peduncle ends in a flower, from the basal part of peduncle two lateral branches arise, which also end in a flower, now this same arrangement occur on these lateral branches.eg. Bougainvillea, Jasmine, Teak, Mirabilis, Dianthus, Nyctanthes.

Multiparous cyme / polychasial – In it peduncle ends in a flower and from the base of it many lateral branches arise which also terminates in flower, this arrangement now also occur on these lateral branches eg. Calotropis (Madar), Nerium, Asclepias, Hamelia

 

 

FLOWER

Flower is defined as highly condensed and modified reproductive shoot. The part from where flower arise is called bract. Flower has short or long flower stalk which is called pedicel. The upper part of pedicel is swollen, spherical shaped or conical which is called thalamus / Receptacle. Floral leaves are present on it.

In a flower there are 4 type of floral leaves are found.

Sepal Petal Stamen Carpel

 

SOME WORDS RELATED TO FLOWER

Complete Flower – When calyx, corolla, androecium and gynoecium are present.

Incomplete Flower – Flower with one of the four whorl missing.

Bisexual Flower – Both gynoecium and androecium present in the same flower.

Unisexual Flower – Androecium (staminate flower) or gynoecium (Pistillate flower) any one of them are present in the flower.

Monoecious Plant – When both male and female flowers are present on the same plant. eg. Cocos, Ricinus, Colocasia, Zea, Acalypha.

Dioecious Plant – When male and female flowers are present on separate plant eg. Mulberry, Papaya.

Polygamous Plant – When unisexual (male or female), bisexual and neuter flowers are present on the same plant eg. Mango, Polygonum.

Monocarpic Plant – The plant which produces flowers and fruits only once in life eg. Pea, Mustard, Bamboo, Agave.

Polycarpic Plant – The plants which produces flowers and fruits many times in life, eg. Pear, Mango.

Achlamydeous Flower – Flowers are naked without sepals and petals eg. piperaceae.

Monochlamydeous Flower : Only one accessory whorl is present (Perianth) eg. Polygonaceae, Liliaceae.

Dichlamydeous Flower : Both accessory whorls present in flower.

Hemicyclic or Spirocyclic Flower : Some of the floral parts are in circles and some are spirally arranged. eg. Ranunculaceae.

Cauliflory :Production of flowers on old stem from dormant buds eg. Artrocarpus, Ficus.

 

Symmetry of flower – If the floral leaves are cyclic arranged in a flower, then it is called cyclic flower. If floral leaves are spirally arranged then it is called spiral flower. Floral symmetry is of three type –

  • Actinomorphic / Radial / Regular – When flower is divided by any vertical plane into two equal halves, then it is called actinomorphic flower eg. Mustard, China rose, Datura, Chilli.
  • Zygomorphic / Bilateral – When the flower is divided into two equal halves only by one vertical plane, then it is called zygomorphic flower eg. Pea, Bean, Gulmohur, Cassia.

INSERTION OF FLORAL LEAVES

Hypogynous condition – When petals, sepals and stamens are situated below the ovary, the flower is called hypogynous and in this condition ovary will be superior. eg. mustard, Chinarose, Brinjal.

Perigynous condition – In it thalamus grow upwardly and form a cup shaped structure. Gynoecium is situated in the centre and other parts of flower are located on the rim of the thalamus almost at the same level. It is called perigynous. The ovary here is said to be half inferior eg. plum, peach, rose.

Epigynous condition – The margin of thalamus grows upward enclosing the ovary completely and getting fused with it, the other parts of flower arises above the ovary, the ovary is said to be inferior and this condition is known as epigynous eg. Guava, Cucumber and ray florets of sun flower

Notes :

Bracts : Bracts are specialized leaves present in axis of flower.

Bracteate – The flower which have bract is called bracteate flower.

Involucre – The whorl of bract surrounding peduncle is called involucre.

Involucel – Group of bracteole is called involucel.

Spathe – In flowers when large bract completely encloses whole inflorescence, then it is called spathe. eg. Banana, Maize.

Petaloid bract – When the size of bract of flower is greater than size of flower and these are of various coloured then it is called petaloid bract. eg. Bougainvillea.

Glumes – Small, dry, scaly bracts are called Glumes. eg. Wheat, Grass.

 

  • CALYX

The outermost whorl of flower is called calyx. Each member of this whorl is called sepal when all the sepals are free from each other, then it is called poly-sepalous condition eg. Mustard, Radish. When the sepals are fused each other, then it is called gamosepalous condition eg. Cotton,

  • DURATION OF SEPALS

Caducous – Sepals fall just at the time of opening of flower bud. eg. Poppy.

Deciduous – Sepals fall after pollination eg. Mustard

Persistant – If sepals do not fall and remain attached to fruit. eg. Tomato, Capsicum, Brinjal, Cotton, Datura.

* Sometime below calyx, a whorl similar to sepals is found which is called epicalyx. eg. Malvaceae family.

 

COROLLA

The second whorl of flower is called corolla and each member of it is called Petals. When the shape and size of petals are similar then it is called symmetrical while when they are not similar then they are asymmetrical. When all the petals are free, then it is called polypetalous while when petals are fused, then it is called gamopetalous.

Forms of Corolla –

POLYPETALOUS

  • Cruciform – 4 petals are present in it. The lower narrow part of petal is called claw while the outer broad part is called limb. These petals are arranged crosswise. eg. Radish, Mustard.
  • Caryophyllaceous – It consists of 5 petals the claw of petals are short and the limb of petals from right angle to the claw eg. Dianthus.
  • Rosaceous – It consist of 5 or more petals. Claws are absent in it and limbs are spread regularly outwards. eg. Rose, Coconut.

 

GAMOPETALOUS

Campanulate – Five petals are arranged like bell. eg. Tobacco, Raspberry, Campanula.

Funnel shaped or infundibuliform – Funnel like petals arrangement eg. Datura, Railway creeper. Tubular – Petals are like tube eg. Disc florets of sunflower.

ZYGOMORPHIC POLYPETALOUS COROLLA –

Papilionaceous – Five petals are present. It’s posterior petal is largest and is known as standard or vexillum. Vexillum covers two lateral petals which are called as wings and the innermost basal petals are united to form a keel or carina. Both lateral parts covers the keel. eg. Pea, Gram, Arher

ZYGOMORPHIC GAMOPETALOUS COROLLA

Bilabiate – The petal of gamopetalous corolla is divided into two lips. The place between two lips is called corolla mouth. eg. Ocimum, Salvia.

Personate – In this case the corolla is bilabiate but the two lips are near to each other eg. Antirrhinum

Ligulate – The upper part of corolla is long, flattened which is attached with short narrow tube. eg. Ray florets of sunflower.

AESTIVATION

The mode of arrangement of sepals or petals in floral bud with respect to the other members of the same whorl is known as aestivation. It is of following types –

Valvate – When the petal of a whorl lie adjacent to each other petal and just touches it. eg. Calotropis, Custard-apple, Mustard.

Twisted – In it one part of a petal covers adjacent petals and the other part is covered by posterior petal. One margin of the petal overlaps that of the next one, and the other margin is overlapped by the third one. eg. Cotton, Ladyfinger, Chinarose.

Imbricate – When both margin of the one petal are covered by the others two petals and both margin of another one, covers other, Rest are arranged in twisted manner. It is of two types –

Ascending imbricate – The posterior petal is innermost i.e., its both margins are overlapped. eg.

Cassia, Bauhinia, Gulmohur etc.

Vexillary or Descending imbricate – The anterior petal is innermost and posterior petal is outermost & largest. eg. Pea, Bean.

Quincuncial – It is a modification of imbricate type. Out of the five petals, two are completely internal, two completely external and in the remaining petal, one margin is internal and the other margin is external. eg. Murraya, Ranunculus.

PERIANTH

When there is no distinction between calyx and corolla the whorl is described as perianth.

Individual perianth segments are called Tepals. Green tepals are called sepaloid and coloured tepals are called petaloid. Tepals are free (polytepalous) or fused (gamotepalous). eg. Liliaceae and Graminae family

 

ANDROECIUM

It constitutes the third whorl of the flower and is made up of one or more stamens. Each stamen consist of filament, anther and connective. Each anther is usually bilobed and each lobe has two chambers the pollensac. The pollen grains are produced in pollensac.

Attachment of filament to anther lobe :

The attachment of filament to another lobe is of 4 type –

Adnate – Filament runs through the whole length of the anther from the base to the apex. eg.

Michelia (Champa), Magnolia

Basifixed – Filament is attached to anther by its base. eg. Datura, Radish, Mustard.

Dorsifixed – The filament is attached at the centre to the back of the anther. eg. Passion flower Versatile – Filament attached to the back of the anther at a point only, thus the anther can swing freely. eg. Wheat, grass, maize.

Cohesion of stamens :

When the floral parts of similar whorl are fused, then it is called cohesion. When the stamens of an androecium are free from one another, it is called polyandrous condition.

  • Adelphous : when stamens are united by their filament only, it is called adelphous. It is of following types –

Monoadelphous – When all the filaments are united into a single bundle but anthers are free from each other. In this type of cohesion a tube is formed around the gynoecium which is called staminal tube eg. Cotton, Hollyhock, Ladyfinger.

Diadelphous – When the filaments are united in two bundles but the anther remains free eg. Gram, Pea, Bean. In these plants from 10 stamens, 9 stamens are arranged in bundle while 1 remains free.

Polyadelphous – When filaments are united into more then two bundles. eg. Citrus, Castor.

  • Synandrous – When anthers as well as filaments of stamens are united through their whole length. eg. Colocasia, Alocasia, Momordica, Cucurbitaceae family.
  • Syngenesious – In it only anthers are united in bundle but filaments remain free eg. Compositae family.

Adhesion of stamens :

When the stamens are attached to other parts of flower, then it is called adhesion of stamens.

Epipetalous – When stamens are attached to petals. eg. Brinjal, Datura, Tobacco, Sunflower, Potato.

Epiphyllous – When stamens are attached to tepals. eg. Onion, Lily.

Gynandrous – When stamens are attached to gynonecium either throughout their whole length or by their anther eg. Calotropis.

Length of stamens :

Didynamous – When four stamens are present, out of them two are long and two are short, then it is called didynamous. eg. Labiatae family.

Tetradynamous – When there are six stamens and they are arranged in two whorls. In outer whorl, there are two short stamens while in inner whorl, there are four long stamens, this condition is called tetradynamous. eg. Cruciferae family.

 

  • GYNOECIUM (PISTIL)

It is the fourth and second essential whorl of the flower. It is female part of the flower comprising of the inner whorl of megasporophylls in the form of carpels bearing ovules. It consists of ovary, style and stigma. Ovary is the enlarged basal part, on which lies the elongated tube the style, the style connects the ovary to the stigma. The stigma is usually at the tip of the style and is receptive surface for pollen grains. The gynoecium may be monocarpellary or multicarpellary. If only one carpel is present in gynoecium this condition is called monocarpellary. f more than one carpel is present in gynoecium this condition is called polycarpellary.

If all the carpels in polycarpellary / multicarpellary condition are free, then condition is called apocarpous.

If all the carpels are fused together, then condition is called syncarpous.

  • COHESION OF CARPEL
    • In syncarpous gynoecium four types of cohesion are found
    • When ovaries are fused, but stigma and style are separated with each other, eg. Dianthus,

Plumbago

 

    • Ovary and style are fused, but stigma are not fused. Malvaceae family. Hibiscus rosasinensis, cotton. When stigma are fused but the ovary and style are free. eg. Calotropis, Cassia fistula, Nerium.

Carpels are completely fused. This condition is found in max. flowers, eg. Mustard, Radish, Tomato.

 

  • PLACENTATION

The ovules are attached on ovary walls on one or more cushion called placenta. The arrangement of ovule within ovary wall is known as placentation. It is of following types –

Marginal : Marginal placentation is found in unilocular ovary. The placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows. eg. Leguminosae.

Parietal : This type of placentation is found in unilocular syncarpus ovary. In it the ovule develops on the innerwall of the ovary or on peripheral part. Ovary become bi or multilocular due to formation a false septum eg. Cucurbita, Argemone, and Cruciferae family (Mustard).

Axile : It is found in multicarpellary syncarpous gynoecium. The fusion margin of carpels grown inward and meet in the centre of the ovary. Thus an axis forms in the centre of ovary, thus ovary becomes multichambered. The ovules are born at the central axis. Number of these chambers are equal to the number of carpel eg. Potato, China rose, Onion, Lemon, Orange, Tomato.

Free central : This type of placentation is found in syncarpous gynoecium. In it, the ovary is unilocular and the ovules are borne on the axis in the centre of the ovary. septum are absent in ovary. Placentation is axile in beginning. After sometimes walls of chamber destroy and only ovulated central axis left. eg. Primrose, Dianthus (Caryophyllaceae).

Superficial – This type of placentation is found in multicarpellary syncarpous gynoecium. The ovules are attached on the walls of locule eg. Nymphea (Water lily).

Basal : The ovary is unilocular and a single ovule is borne at the base of ovary. eg. Marigold, Sunflower (Asteraceae family).

FRUITS

A fruit is a fertilized and ripened ovary which consist of (i) Pericarp (fruit wall), (ii) seed.

The seeds are protected inside fruit. But in some fruits seeds are not found like in grapes, banana and such type of fruits are seedless fruit.

If a fruit is formed without fertilization of the ovary it is known as parthenocarpic fruit.

Pericarp : After ripening, the ovary wall change into pericarp. This pericarp may by thick and fleshy or thick and hard or thin and soft. Pericarp is differentiated into 3 layers:

 

 

Epicarp :- It is the outermost layer, which is also called rind

Mesocarp :- It is the middle layer.

Endocarp : It forms the innermost layer.

TRUE FRUIT : When the fruit is developed only from the ovary, the fruit is called as true fruit. eg.

Mango, Coconut, Zizyphus

FALSE FRUIT OR PSEUDOCARP : In some fruits, in place of ovary, some other parts of flower like thalamus, inflorescence, calyx are modified to form a part of fruit. These types of fruit are called false fruits. eg. Apple, Strawberry, Pear.

CLASSIFICATION OF FRUIT

Fruits are divided in three groups

✧ Simple ✧ Aggregate ✧ Composite

SIMPLE FRUIT :-

These fruit develop from monocarpellary ovary or multicarpellary syncarpous ovary. Only one fruit is formed by the gynoecium. Simple fruits are of two types – ✧ Fleshy fruit ✧ Dry fruit

Fleshy Fruit:- These fruit develop from superior or inferior syncarpous gynoecium. These may be unilocular or multilocular. These fruits are indehiscent. Dispersal of seeds occur after pericarp is destroyed.

Fleshy fruits are of following types :

Drupe fruit :- These fruit develops from mono or multicarpellary, syncarpous, superior ovary. In these fruits endocarp is hard and stony so these fruits are also called stony fruits. eg. Mango, coconut almond, Peach walnut, plum. Brachysclereids are present in endocarp.

In mango edible fleshy part is mesocarp and the part where seed is protected is called as endocarp.

In ber, epicarp and mesocarp both are edible part.

The rind of Almond and walnut are endocarp and their edible part is seed.

In coconut epicarp is hard and thin while mesocarp is thick and consist of hard fibers The endocarp is hard and seed is protected in it. Endosperm is edible in coconut.

Berry : These fruits develop from mono or multicarpellary syncarpous ovary. Ovary may be superior or inferior, Placentation is axile or parietal. In these epicarp is thin and seeds are embedded in fleshy part. Initially seeds are attached with placenta of fruit but after maturation these seeds are deteched with placenta and are spread randomly in fleshy part.

  • Plants with superior ovary = Tomato, Grapes, Brinjal.
  • Plants with inferior ovary = Guava, Banana.

 

Date palm is one seeded berry. In it pericarp is divided into epicarp, mesocarp and endocarp.

Epicarp is thin and soft while mesocarp is thick and fleshy and endocarp is thin like a membrane.

Which is attached with seed.

Arecanut is one seeded fibrous fruit berry. When its thick fibrous layer is removed then seed comes out which is hard.

Pepo – These fruit develops from tricarpellary, syncarpous and inferior ovary. This fruit is unilocular and have parietal placentation. These fruits are fleshy and spongy. sometime fruits are bitter in taste due to presence of tetracyclic triterpine in flashy pulp. eg. fruits of cucurbitaceae family.

Pome – This fruit develops from bi or multicarpellary syncarpous inferior ovary. The rind and fleshy pulp are made up of thalamus. The main part of ovary is hard and dry and remain inside the fruit. Seeds are present in it. eg. Apple, Pear.

Hesperidium : This fruit develops from multicarpellary, syncarpous, superior ovary. This fruit is specialy found in plants of Rutaceae family. eg. Orange, Lemon, Citrus fruit.

Epicarp of these is made up of thick rind which is leathery and many oil glands are found in it. Mesocarp is white fibrous structure which is attached with epicarp. Membranous endocarp projects inward and form many chambers. Many glandular hairs are present on the inner side of endocarp. These glandular hairs are only edible parts.

Simple Dry Fruit – Pericarp of simple dry fruit is hard and dry and not differentiated into epicarp, mesocarp and endocarp. Such fruits are called dry fruit.

Simple dry fruits can be divided into following three groups : ✧ Indehiscent ✧ Dehiscent ✧ Schizocarpic

Indehiscent fruits : These simple dry fruits are generally of small size and single seeded pericarp does not rupture even after maturity.

Cypsela : It is a small, single seeded dry fruit which develops from bicarpellary, syncarpous inferior ovary. Pericarp and seed coat are free from each other. In these fruits a bunch of hair is attached with the fruit which is known as Pappus. Pappus helps in fruit dispersal. eg. Compositae family Plants.

Caryopsis : These are small, single seeded dry fruits. It develop from monocarpellary, superior ovary. Pericarp of these fruits is fused with the seed coat and form a joint surface. These fruits are present in family gramineae. Wheat grain or rice grain is a fruit.

Achene : These are single seeded fruit which develops from monocarpellary superior ovary. In it, pericarp is free from the seed coat eg. Clematis, Mirabilis, Boerhaavia

Nut : This is a single seeded fruit which develop from monocarpellary syncarpous superior ovary. In it pericarp is hard eg. Quercus (oak), Anacardium occidentale (Cashewnut) Trapa, (Water chest-nut), Litchi.

In Litchi epicarp and mesocarp is fused and give leathery apperence. Endocarp is membrane like thin. Outer seed coat grows forward and forms an additional coat around the seed which is called as aril. In mature fruit, this aril is fleshy and is only edible part

Samara : These are dry indehiscent one seeded feathery fruit. It develops from bi or tri carpellary, syncarpous and superior ovary. The main character of these fruits is wing like structure develops from its pericarp which helps in dispersal. eg. Holoptelia

Dehiscent Fruits : After ripening pericarp are ruptured and seeds are dispersed outside. ✧ Legume or pods : These fruits develop from monocarpellary, unilocular, superior ovary. It is generally long and multiseeded fruit. Dehiscense of fruit occurs at both sutures i.e. Dorsal and ventral side. Dehiscence start from apex and reaches to basal part. eg. Pea, Beans.

When only one or two seeds are present in fruit, then it is also called as pod.

Follicle : It is also multiseeded fruit which develops from superior unilocular, monocarpellary ovary but the dehiscence of it occur only at ventral suture. eg. Asclepias, Rauwolfia, Vinca, Michelia (Champa), Delphinium.

Siliqua : This fruit develops from bicarpellary, syncarpous superior ovary with parietal placentation. Dehiscence occurs at both dorsal and ventral suture and starts from lower part and proceeds upward. Due to formation of false septum ovary become bilocular. On false septum, seeds are attached, This type of fruit is found in Cruciferae family. eg. Mustard.

Silicula : A short broad siliqua is known as Silicula. It is also found in Cruciferae family. eg.

Candytuft (lberis amara), Capsella,

Capsule : This is dry multichambered and multiseeded fruit and develop from multicarpellary syncarpus, superior ovary. In it, Axile placentation is found and dehiscence occurs by various methods. Poricidal (Poppy), loculicidal (cotton), septifragal (Datura), septicidal (Lineseed).

Schizocarpic fruit : It is a multiseeded fruit. After ripening, it is devided into mericarp and seeds come out after destruction of pericarp. The fruits develop from mono or bi or multicarpellary superior or inferior ovary. The mericarp contains one or two seeds.

AGGREGATE FRUIT :-

These fruits develop from multicarpellary apocarpous ovary. Because in apocarpous ovary, each carpel is separated from one another, therefore it forms a fruitlet. These fruits are made up of bunch of fruitlets which is known as etaerio.

COMPOSITE FRUIT :-

All composite fruits are false fruits.

This type of fruit differ from aggregate fruit that in place of single ovary many ovaries and other floral parts combine together to form fruit. In composite fruits, generally whole inflorescence is modified into fruit. These are of two types.

Sorosis : This fruit develops from spike, spadix or cartkin inflorescence. Peduncle become thick spongy and woody. eg. Jack fruit, Pandanus (screwpine), Pineapple

In jack fruit (Kathal) pistillate flowers are developed around the peduncle. In fruit formation pericarp become spongy and fused.

In Pine apple peduncle bracts and perianth become fleshy. Due to the fusion of perianths of flower a composite fruit is formed.

In mulberry perianth become fleshy and calyx of every flower becomes thick, sweet and fleshy and are edible.

Syconus : This fruit develops from hypanthodium inflorescence. eg. Ficus species like fig, Peepal

DISPERSAL OF FRUITS AND SEED

The seeds falling directly under the mother plant have to germinate and develop under limited food supply and space. To overcome this problem, the fruits and seeds have developed several special devices for wide dispersal.

The natural agents like wind, water, animals and even mechanism of dehiscence in some fruits, help the seeds and fruits to disperse from one place to another, and to long distances from the parent plant.

WIND (Anemochory): In the species where the seeds are light in weight or have some accessory part to help dissemination, are dispersed by the air current.

In the members of Asteraceae, the calyx is modified into hair like structures called pappus. They persist in fruit and open out like umbrella, helping the seeds to float in the air.

WATER (Hydrochory): The fruit and seeds with specialised devices which may be in the form of spongy and fibrous outer walls as in coconut and spongy thalamus as in lotus, and small seeds with airy aril as in water lily, float very easily in water and are carried away to long distances with the water current.

ANIMAL (Zoochory): The edible fruits like guava, grape, fig and plum are dispersed by birds and even human beings by feeding on them and passing out undigested seeds with faeces or by carrying them to other places for later feeding.

 

 

THE END OF CRP 201 LECTURE NOTE 1

 

LEAVE A REPLY

Please enter your comment!
Please enter your name here