5. Morphology of Flowering PlantsTHE ROOT:

Root is a part of a plant body that –

Bears no leaves and nodes.

typically lies below the surface of the soil but can also be aerial 

The first root that comes from radicle

major functions of roots :

1) absorption of water and inorganic nutrients

2) anchoring of the plant body to the ground

3) storage of food and nutrients

4) Prevent soil erosion.

5) In response to the concentration of nutrients, roots also synthesise cytokinin, which acts as a signal as to how fast the shoots can grow.

6) Storage of food and nutrients.

7) The roots of most vascular plant species form mycorrhizas

Tap Root System Fibrous Root System Adventitious Roots

In majority of the dicotyledonous plants

In monocotyledonous plants They commonly occur in monocots and pteridophytes but also in many dicots

The primary roots and its branches constitute the tap root system

primary root is short lived and is replaced by a large number of roots

perform functions other than absorption

radicle elongate to form primary root which grows inside the soil and lateral roots (secondary, tertiary, etc.)

These roots originate from the base of the stem

Roots arise from parts of the plant other than the radicle

in the mustard plant in the wheat plant Grass and the banyan tree

Regions of the Root: The root apex can be differentiated into four distinct regions:

The root cap- it is the covering of the root tip.  It functions to protect the zone of cell division. As the root grows and pushes through the soil the cells on the outer surface of the root cap worn away.  The calyptrogen replaces the worn out cells of the root cap by adding cells due to rapid rate of cell division. 

The zone of cell division - it is the region of meristematic activity. The cells of this region are very small,

thin-walled and with dense protoplasm. They divide repeatedly.

The zone of elongation- it is immediately behind the zone of cell division. The cells of this zone take water and increase in length. Both these regions are responsible for continued growth of the root. 

The zone of maturation – it is just behind the zone of elongation.  Externally, this zone is characterized by the presence of a large number of unicellular root hair each of which originates from the epidermal cell. These root hair are short-lived and new ones are formed continually behind the zone of elongation as the root grows. Internally, the cells in the zone of maturation differentiate into various permanent tissues such as xylem tracheids, vessels, sieve tubes and fibres.  The zone of maturation is the longest of all the regions of root. 

Modifications of Root:

Roots in some plants change their shape and structure and become modified to perform functions other than absorption and conduction of water and minerals. They are modified for –

• Storage roots are used for storage of food• Prop roots and stilt roots offer additional support of plant body.• Climbing roots aid in climbing.• In epiphytes, velamen absorbs moisture from air.• Floating roots help to maintain buoyancy in water.• Pneumatophores help in root aeration where roots suffer from oxygen deprivation in marshy lands.• Reproductive roots perform reproductive functions.• Parasitic roots (haustoria) penetrate into host stem and enter vascular bundles from which the

parasites absorb the nutrients.• Assimilatory roots having chlorophyll help in photosynthesis.

Tap Root ModificationsIn some plants the tap roots store reserve food for which they become swollen and assume different shapes.

Fusiform root - In radish the modified tap root is thickened in the middle and tapers towards both ends.e.g., Raphanus sativus (Radish)Napiform root - In beetroot the modified tap root is greatly swollen at the base, but abruptly narrows into a tail-like portion. e.g., Beta vulgaris (Beetroot)Conical root - In carrot the modified tap root is conical. It is broad at the base and gradually tapers towards its apex. e.g., Daucas carota (carrot)Nodulated roots: In legumes, the roots containing Rhizobium help in the fixation of atmospheric nitrogen. Adventitious Root ModificationsTuberous or tubercular root, the modified adventitious root is swollen without any definite shape. It is always produced singly and not in clusters. e.g., Ipomoea batotas (Sweet potato) Fasciculated roots , a number of adventitious roots arise as a cluster, from almost the same level at the base of the stem. e.g., Asparagus, Dahlia Nodulose roots, the root becomes swollen at its tip. e.g., Curcuma amada, (mango ginger) Moniliform or beaded roots, the roots show beadlike swellings at frequent intervals. e.g., Momordica Annulated roots adventitious roots have a series of ring-like swellings on their surface. E.g., Ipecac

Aerial Root Modifications : Aerial roots are adventitious roots which develop from the aerial parts of the plant to perform various functions.

• For Mechanical Support

Prop roots e.g., Ficus benghalensis (Banyan) : In banyan the adventitious roots arise from the horizontal branches and grow vertically downwards. After reaching the soil they become thick and woody. Thus, they function as pillars giving mechanical support to the branches. Hence, they are also known as columnar roots.

Stilt roots e.g. maize,sugarcane : the adventitious roots arise from the lower part of the main stem and grow obliquely towards the soil. They serve to keep the plant erect by giving additional support. Climbing roots or clinging roots e.g., Piper betel, Pothos, etc : These roots arise from the nodes and help in attaching the climbing stem firmly to a support like a tree or a wall, by various mechanisms.

• For Vital Functions

Haustoria or sucking roots e.g. Cuscuta : Parasites like Cuscuta develop a kind of root which penetrates into the tissue of the host plant and help to draw nutrients from the host by sucking it.

Respiratory roots or breathing roots or pneumtophores :e.g., Avicennia, Rhizophora. A number of plants growing in marshy water-logged soils which contain almost no air, develop some branches which grow vertically upwards into the air. These roots are called breathing roots or pneumatophores. Each such root is provided towards the upper end with numerous pores through which gases diffuse in and out.

Floating roots e.g., Jussiea: In Jussiea which is an aquatic plant, special spongy roots called floating or respiratory roots arise from the plant. They are adventitious and enclose a tissue called aerenchyma. These roots usually develop above the level of water and serve to store up air and help in buoyancy of the plant. In addition, the floating roots may also perform the respiratory function. Hence, they are also called respiratory roots.

Epiphytic roots e.g., Vanda: In epiphytes like orchids which grow on other plants, special adventitious roots called epiphytic roots are produced. The outer region of the root is made up of a special tissue called the velamen. This tissue absorbs moisture from the air and makes it available to the plant. These roots do not penetrate the host tissue like parasitic roots.

Propagative roots, e.g. Canada thistle, cherry : roots form adventitious buds that develop into aboveground shoots, termed suckers, which form new plants.

THE STEM:

• The stem is the ascending and aboveground part of the axis bearing branches, leaves, flowers and fruits.

• It develops from the plumule of the germinating seed.

• The stem bears nodes(where leaves are born) and internodes(portions between two nodes). • Stem is generally green when young and later often become woody and dark brown. • Grows and bends towards light (positively phototropic) and away from gravity (negatively

geotropic)• Bears vegetative buds which could be terminal (apical bud) for plant to grow upwards or axillary

(bud in the axil of leaf) which give rise to lateral branches.• Bears floral buds (terminal or axillary) that grow into flowers.

Functions of Stem:

• 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.

Modifications of Stem:

• Underground stem Modifications:

• Sucker: It is the lateral branch originate from the basal and underground portion of the main stem, grow horizontally beneath the soil and then come out obliquely upward giving rise to leafy shoot. It may be green or nongreen, possess nodes and internodes and scaly leaves. Eg. In banana, pineapple and Chrysanthemum, Mint.

•

• Rhizome: it is an underground, fleshy stem of indefinite growth. Nodes and inter nodes present. Nodes bear scaly leaves and axillary buds. It is cylindrical or irregular in shape, grows horizontally. Adventitious roots develops from lower surface. E.g. ginger, turmeric stem is modified to store food in them. They also act as organs of perenation to tide over conditions unfavourable for growth.

• Corm(condensed rhizome): it is spherical swollen under ground stem which grows vertically e.g. zaminkand, Colocasia are modified to store food in them. They also act as organs of perenation to tide over conditions unfavourable for growth. Nodes and inter nodes present. Nodes bear scaly leaves and axillary buds. Adventitious roots develops from lower surface. Corm bear foliage leaves.

• Stem tuber : it is swollen tuber like stem tips devoid of adventitious roots, foliage leaves and covered by corky skin. A tuber bears a number of spirally arranged depressions called eyes(represent nodes). E.g. potato

• Bulbs: underground condensed stem which possess apical bud and fleshy scaly leaves. Adventitious roots develops from reduced disc shaped stem. Garlic, onion.

• Aerial stem Modifications: • Runner:

The runner arises from the base of the stem as a lateral branch and runs horizontally along the surface of the soil. It develops distinct nodes and internodes. At each node, the runner produces roots below and leaves above. Runners are the device to spread the plant quickly. E.g., Oxalis, cynodon dactylon.

• Stolon: lateral branches called stolons originate from the underground stem. The stolons grow horizontally

or obliquely to a varying distance crossing small obstacles, Ultimately their end (terminal bud) develops into a new plant. E.g. Colocasia, strawberry

• Offset:

An offset is a short thick internode which produces a new plant at its tip. The offsets grow in all directions from the main stem of the parent plant. If any accidental injury results in the separation of these units, each is capable of leading an independent existence. E.g., Pistia, Eichhornia.

• Stem Tendril: Tendrils develop as modifications of the stem and spirally coiled , help plants to climb. The terminal bud gives rise to a tendril in Cissus quandrangularis and the axillary bud becomes modified into a tendirl in Passiflora, in gourds (cucumber, pumpkins, watermelon) and grapevines.

• Stem Thorn: The thorn is a hard, straight, and pointed structure. In Bougainvillea and Duranta, the axillary bud is modified into a thorn. In Carissa the terminal bud is modified into a pair of thorns. The thorns check the rate of transpiration and protect the plants from herbivore grazing. Citrus Thorns are small, modified stems, spines are modified superficial leaves and prickles are sharp, pointed structures without vascular tissue, arising on stem, petioles and inflorescence.

• Phylloclade: A phylloclade is a flattened stem of several internodes functioning as a leaf. In Opuntia the stem is modified into a green flattened structure called Phylloclade. On the surface of the phylloclade, clusters of spines are formed. These spines are the modified leaves of the axillary bud. These spines not only check the rate of transpiration but also protect the plant from herbivores. The phylloclade has distinct nodes and internodes. E.g., Opuntia In Muehlenbeckia the stem is a thin, green, flat structure made up of nodes and internodes. Initially small normal leaves are formed but later only scale leaves.

• Cladodes: in some xeric plants branches of limited growth modified into leaves for photosynthesis, the main stem is normal and leaves modified into spines or scales. e.g. Ruscus, Asparagus

• Bulbil: Bulbil is a speical multicellular body essentially meant for reproduction. In Agave the floral buds are modified into bulbils. These bulbils get detached, come in contact with the soil and develop into new plants. In Dioscorea the axillary bud develops into a bulbil. This bulbil detaches from the mother plant and grows up into a new independent one.

THE LEAF:• The leaf is a lateral, generally flattened structure borne on the stem.

• It develops at the node and bears a bud in its axil (axillary bud)later develops into a branch.

• Leaves originate from shoot apical meristems and are arranged in an acropetal (youngest at the tip)order.

•They perform photosynthesis.

Structure of leaf:

• A typical leaf consists of three main parts: • leaf base(hypopodium)- leaf is attached to the stem by the leaf base

• petiole(mesopodium)- The petiole help hold the blade to light. Long thin flexible petioles allow leaf blades to flutter in wind, thereby cooling the leaf and bringing fresh air to leaf surface.

• Lamina(epipodium)- The lamina or the leaf blade is the green expanded part of the leaf with veins and veinlets. The shape, margin, apex, surface and extent of incision of lamina varies in different leaves.

• The leaf may bear two lateral small leaf like structures called stipules.

• In monocotyledons, the leaf base expands into a sheath covering the stem partially or wholly.

• In some leguminous plants the leaf base may become swollen, which is called the pulvinus. Venation:

• Veins provide rigidity to the leaf blade and act as channels of transport for water, minerals and food materials.

• The arrangement of veins and the veinlets in the lamina of leaf is termed as venation.

Reticulate Venation Parallel Venation

veinlets form a network within a lamina veins run parallel to each other within a lamina

Leaves of dicotyledonous plants Leaves of monocotyledonous plants

Types of Leaves:

Simple leaf Compound leaf

A leaf is said to be simple, when its lamina is entire or when incised, the incisions do not touch the midrib.

When the incisions of the lamina reach up to the midrib breaking it into a number of leaflets, the leaf is called compound.

A bud is present in the axil of petiole in simple leaves

A bud is present in the axil of petiole in compound leaves but not in the axil of leaflets of the compound leaf.

Pinnately compound leaf Palmately compound leavesa number of leaflets are present on a common axis, the rachis, which represents the midrib of the leaf

the leaflets are attached at a common point, i.e., at the tip of petiole.

Leaf has an elongated axis Axis reduced

Leaflets born in rows Leaflets born in cluster

as in neem, rose, Acacia, coriander, carrot as in silk cotton, wood apple, Butea monosperma

Phyllotaxy:

Phyllotaxy is the pattern of arrangement of leaves on the stem or branch.

Alternate Arrangement Opposite Arrangement Whorled Arrangement

a single leaf arises at each node in alternate manner

a pair of leaves arise at each node and lie opposite to each other

more than two leaves arise at a node and form a whorl

in china rose, mustard and sun flower plants

in Calotropis and guava plants in Alstonia

Modifications of Leaves: Leaves are often modified to perform functions other than photosynthesis.

Tendrils: In glory lily (Gloriosa superba) the leaf apex is modified into a tendril. In pea (Pisum sativum) the terminal leaflets of an unipinnately compound leaf are modified into tendrils. In Lathyrus or wild pea, the entire leaf is modified into a tendril. In Clematis and Smilax, the petiole and stipules respectively, are modified into tendrils for climbing.Phyllodes:A phyllode is the petiole or rachis of a leaf which is modified into a green flat structure for the purpose of photosynthesis. In such a leaf the lamina is poorly developed. In Acacia melanoxylon, the petiole is flattened, green and becomes a phyllode. The leaflets and secondary rachii drop off. In Parkinsonia aculeata, the secondary rachii are modified into phylodes which are photosynthetic. The primary rachis is modified into a spine.Leaf Spines:In some plants, leaves or parts of leaves may be modified into spines. In Opuntia (prickly pear) leaves are poorly developed and fall of very early, but the minute leaves of the axillary bud are modified into spines. In Argemone (prickly poppy), the leaf margin is modified into small spines. In Zizyphus the stipules are modified into spines. The spines act as defensive structures.Scale Leaves:In many desert plants, the leaves are highly reduced and appear as scales. The scale leaves are thin, membranous, dry, stalkless and brownish or colourless. In plants where the leaves are reduced to scales in order to minimise transpiration, the function of photosynthesis is relegated to the stems (cladodes).Bulb: The fleshy leaves of onion and garlic store food. Leaf pitchers and bladders: Leaves of certain insectivorous plants such as pitcher plant, utricularia, venus-fly trap are also modified leaves. It is used to trapping and digesting insects.Succulent leaves: Thick swollen leaves modified for storage of water, mucilage and latex e.g. Aloe THE INFLORESCENCE:

• A flower is a modified shoot. • When a shoot tip transforms into a flower the shoot apical meristem changes to floral meristem.

Internodes do not elongate and the axis gets condensed. The apex produces different kinds of floral appendages laterally at successive nodes instead of leaves. It is always solitary. e.g.poppy, china rose.

• The arrangement of flowers on the floral axis is termed as inflorescence.

Type of inflorescences:

Racemose Cymosethe main axis continues to grow the main axis terminates in a flowerthe flowers are borne laterally in an acropetal succession(youngest at tip)

flowers are borne in a basipetal order (youngest at base)

main axis is unlimited in growth main axis is limited in growth

Mustard, sun flower

Acacia, onion, colotropis

THE FLOWER:• The flower is the reproductive unit in the angiosperms. It is meant for sexual reproduction.• A typical flower has four different kinds of whorls arranged successively on the halamus or

receptacle.These are-• accessory organs• Calyx• Corolla• reproductive organs• androecium • gynoecium

• Perianth: when the calyx and corolla are not distinct like lily. • Bisexual: When a flower has both androecium and gynoecium. • Unisexual: A flower having either only stamens or only carpels.Symmetry of Flowers:

Actinomorphic (radial symmetry): When a flower can be divided into two equal radial halves in any radial plane passing through the centre, it is said to be actinomorphic, e.g., mustard, datura, chilli. zygomorphic (bilateral symmetry) When it can be divided into two similar halves only in one particular vertical plane, it is zygomorphic, e.g., pea, gulmohur, bean, Cassia. Asymmetric (irregular): if it cannot be divided into two similar halves by any vertical plane passing through the centre, as in canna.Trimerous: when the floral appendages are in multiple of 3Tetramerous : when the floral appendages are in multiple of 4 Pentamerous: when the floral appendages are in multiple of 5 Bracteates: Flowers with bracts (reduced leaf found at the base of the pedicel), are called bracteate se Ebracteates: Flowers without bracts.

Based on the position of calyx, corolla and androecium in respect of the ovary on thalamus, the flowers are described as-Hypogynous Flower:

• The gynoecium occupies the highest position

• The other parts are situated below ovary

• superior ovary

• e.g., mustard, china rose and brinjal.

Perigynous Flower:

• gynoecium is situated in the centre

• other parts of the flower are located on the rim of the thalamus almost at the same level

• Half inferior ovary

• e.g., plum, rose, peach

Epigynous Flower: • margin of thalamus grows upward enclosing the ovary completely and getting fused with it

• other parts of flower arise above the ovary

• Inferior ovary

• e.g. guava and cucumber, and the ray florets of sunflowerParts of a Flower: Each flower normally has four floral whorls, viz., calyx, corolla, androecium and gynoecium. Calyx:

• outermost whorl

• members are called sepals

• Generally, sepals are green (leaf like)

• protect the flower in the bud stage

• The calyx may be –

• Gamosepalous (sepals united)

• Polysepalous (sepals free)Corolla:

• members are called petals

• Petals are usually brightly coloured

• attract insects for pollination

• corolla may be –

• Gamopetalous(petals united)• Polypetalous(petals free)

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. The main types of aestivation are -

• Valvate

• Twisted

• Imbricate

• Vexillary

Valvate: When sepals or petals in a whorl just touch one another at the margin, without overlapping, as in Calotropis. Twisted: If one margin of the appendage overlaps that of the next one and so on as in china rose, lady’s finger and cotton, it is called twisted. Imbricate: If the margins of sepals or petals overlap one another but not in any particular direction as in Cassia and gulmohur, the aestivation is called imbricate. Vexillary: In pea and bean flowers, there are five petals, the largest (standard) overlaps the two lateral petals (wings) which in turn overlap the two smallest anterior petals (keel); this type of aestivation is known as vexillary or papilionaceous.

Androecium:• Androecium is composed of stamens (male reproductive organ)

• Stamen consists of a stalk or a filament and an anther.

• Each anther is usually bilobed and each lobe has two chambers, the pollen-sacs.

• The pollen grains are produced in pollen-sacs.

• Staminode: A sterile stamen

• Epipetalous: When stamens are attached to the petals e.g. brinjal

• Epiphyllous: when stamens attached to the perianth as in the flowers of lily.

• Polyandrous: when stamens in a flower remain free

• Synandrous: when stamens in a flower remain united.

• Monoadelphous: when stamens united into one bunch or one bundle as in china rose

• Diadelphous: when stamens united into two bundles as in pea

• Polyadelphous: when stamens united into more than two bundles as in citrus.

Gynoecium:

• Female reproductive part of the flower

• It is made up of one or more carpels.

• A carpel consists of three parts namely stigma, style and ovary.

• The elongated tube over kidney is style which connects the ovary to the stigma.

• The stigma is the receptive surface for pollen grains.

• Ovary is the enlarged basal part.

• Each ovary bears one or more ovules attached to placenta.

• After fertilization, the ovules develop into seeds and the ovary matures into a fruit.

• Apocarpous: When carpels are free, as in lotus and rose

• Syncarpous: when carpels are fused, as in mustard and tomato.

Placentation: The arrangement of ovules within the ovary is known as placentation. The placentation are of different types-

• Marginal

• Axile

• Parietal

• Basal

• Free central

• superficialMarginal: The placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, as in pea.Axile: When the placenta is axial and the ovules are attached to it in a multilocular ovary as in china rose, tomato and lemon. Parietal: The ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one-chambered but it becomes two-chambered due to the formation of the false septum, e.g., mustard and Argemone. Free central: When the ovules are borne on central axis and septa are absent, as in Dianthus and Primrose the placentation is called free central.Basal: The placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, marigold.Superficial: The gynoecium is multicarpellary syncarpous and a large number of ovules are born on the walls of loculi without specific order. E.g. Nymphaea

THE FRUIT• The fruit is a characteristic feature of the flowering plants.

• It is a mature or ripened ovary, developed after fertilisation.

• Parthenocarpic fruit: If a fruit is formed without fertilisation of the ovary. It is seedless or has non-viable seeds e.g, banana, grapes. Horticulturists are producing such fruits artificially.

• Pericarp: Fruit wall. The pericarp may be dry or fleshy. • When pericarp is thick and fleshy, it is differentiated into-

• outer epicarp

• middle mesocarp

• inner endocarp.

• In dry fruits pericarp, is thin, dry, papery or thick and woody and but not divided into three regions.• Sometimes along with ovary other floral parts like thalamus,

receptacle or calyx may develop as part of fruit, such fruits are-called false fruits. e.g. apple, pear (thalamus), fig (receptacle).

Common Fruits and their edible parts:Name Type Edible Part1. Banana Berry – simple fleshy Mesocarp and Endocarp

2. Apple Pome – simple fleshy Fleshy thalamus3. Coconut Fibrous Drupe – simple fleshy Endosperm4. Custard Apple Etaerio of Berries – aggregate Pericarp5. Date Palm Berry – simple fleshy Pericarp6. Cashew Nut Nut – simple dry indehiscent Peduncle and Cotyledons7. Mango Drupe – simple fleshy MesocarpB. Orange Hesperidium – simple fleshy Juicy hairs from endocarp,9. Tomato Berry – simple fleshy Pericarp and Placentae10. Pear Pome – simple fleshy Fleshy thalamus11. Pineapple Sorosis – composite Outer portion of receptacle, bracts and perianth12. Fig Syconous – composite Fleshy receptacle13. Litchi Nut – simple Juicy Aril14. Wheat Caryopsis – simple dry indehiscent Starchy Endosperm15. Strawberry Etaerio of achenes- aggregate Succulent thalamus

Kinds of fruits – There are three basic types

• Simple fruit - Develops from single mono-to polycarpellary, syncarpous ovary e.g, pea, tomato.• Aggregate fruit - Collection (etaerio) of simple fruits or fruitlets on same thalamus developing from

polycarpellary, apocarpous (free carpels) ovary e.g. Calotropis• Composite or multiple fruit - Fruit develops from a number of flowers juxtaposed together or from

inflorescence e.g. mulberry, pineapple

THE SEED• The ovules after fertilisation, develop into seeds.

• A seed is made up of a seed coat and an embryo.

• The embryo is made up of a radicle, an embryonal axis and one or two cotyledons.Structure of a Dicotyledonous Seed: It consists of-

• seed coat: outermost covering of a seed• testa - outer layer

• tegmen - inner layer• hilum - a scar on the seed coat through which the developing seeds were attached to the fruit

• micropyle - a small pore above the hilum

• embryonal axis - At the two ends of the embryonal axis are present the radicle and the plumule

• two cotyledons - cotyledons are often fleshy and full of reserve food materials

• radicle – future roots

• plumule – future stem

Endospermic seeds Non-endospermic seedsendosperm is a food storing tissue in seed endosperm is not present in mature seeds

Endosperm not consumed completely during embryo development

Endosperm consumed completely during embryo development

Castor bean, gram and pea

NOTE: Generally, monocotyledonous seeds are endospermic but some as in orchids are non-endospermic.

Structure of Monocotyledonous Seed(maize)• seed coat: membranous and generally fused with the fruit wall.

• Endosperm: bulky and stores food.

• Aleurone layer: a proteinous layer that separates the embryo from endosperm

• Embryo: small and situated in a groove at one end of the endosperm. It consists of –

• Scutellum: one large and shield shaped cotyledon

• embryo axis: short with a plumule and a radicle.

• Coleoptiles: The plumule is enclosed in a sheaths, called coleoptile

• Coleorhizae: Radicle is enclosed in sheaths, called coleorhiza.

SEMI-TECHNICAL DESCRIPTION OF A TYPICAL FLOWERING PLANT:• Various morphological features are used to describe a flowering plant. • The description has to be brief, • It should be in a simple and scientific language and presented in a proper Sequence. • The plant is described beginning with its habit, vegetative characters – roots, stem and leaves and

then floral characters inflorescence and flower parts. • After describing various parts of plant, a floral diagram and a floral formula are presented.

Floral formula: it is represented by some symbols.

• Br = bracteate • K = calyx • C = corolla• P= perianth• A = androecium • G = Gynoecium• G= superior ovary • G = inferior ovary • = male • = female • =bisexual plants• ⊕= actinomorphic • Ǿ or % =zygomorphic • Bracket= Fusion • a line drawn above the symbols = adhesion • Dot on the top of the floral diagram= The position of the mother axis with respect to the flower• Calyx, corolla, androecium and gynoecium are drawn in successive whorls, calyx being the

outermost and the gynoecium being in the centre. Advantage:

• A floral diagram provides information about the number of parts of a flower, their arrangement and the relation they have with one another.

• Floral formula also shows cohesion and adhesion within parts of whorls and in between whorls. DESCRIPTION OF SOME IMPORTANT FAMILIES

Fabaceae:• This family was earlier called Papilonoideae, a subfamily of family Leguminosae. It is distributed all

over the world.

• 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.

• Floral characters

• Inflorescence: racemose

• Flower: bisexual, zygomorphic

• Calyx: sepals five, gamosepalous; 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

• 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).

Solanaceae:

• It is a large family, commonly called as the ‘potato family’. It is widely distributed in tropics, subtropics and even temperate zones.

• Vegetative Characters: Plants mostly, herbs, shrubs and 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

• 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

• Fruits: berry or capsule

• Seeds: 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).

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: petal six (3+3), often united into tube; valvate aestivation

• Androcium: stamen six, (3+3)

• Gynoecium: tricarpellary, syncarpous, ovary superior, trilocular with many ovules; axile placentation

• Fruit: capsule, rarely berry

• Seed: endospermous

• Economic Importance: Many plants belonging to this family are good ornamentals (tulip, Gloriosa), source of medicine (Aloe), vegetables (Asparagus), and colchicine (Colchicum autumnale).