Root : Descending
portion of plant axis, develops from radical of embryo; anchors the
plants in the soil and serves as organ of uptake of water and inorganic
Adventitious root(s) : Roots arising from any part of the plant except its radical e.g., banyan tree, mangroves.
Climbing roots :The plants with weak stem bear climbing roots at their nodes , they enable the plant to climb the support e.g. Lvy , Betel.
Conical : Tap root which is broad at the base tapering gradually to the apex, e.g. carrot.
Conical root :The base of the root is board but gradually tapers towards the apex e.g. carrot.
Epiphytic roots :An epiphytic plant grows in the crevices of other plants. These fix the plants in the crevices e.g. Vanela.
Fasciculated roots :When
many tubercular roots occur in a single cluster of fascicle they are
called fasciculated roots. This modification is also meant for stronge
of food e.g. Asparagus , Ruellia and Dalhia.
Fibrous root : Repeated branching of the radical; common in monocosts, e.g., onion maize, sugarcane etc.
Fusiform root : The root is swollen in the middle and gradually tapers towards the e.g. Radish.
Modified root : The tap roots are usually modified for stronge of food. Main modified forms of tap root are as follows :
Moniliform roots :These are also called as beded roots because these arise as swellings at frequent intervals e.g. Fortulaea and Mormordica.
Napiform root :It is very much swollen at the upper end and suddenly tapers at the other end e.g. Beet root, tumip.
Nodulated root :The secondary or tertian branches of tap root become nodulated , symbiotic bacteria live inside these nodules e.g. Pea and gram.
Parasitic or Haustorial roots :The Plant developes sucking roots which penetrate through the stem of host plant and rob the food e.g. cusuta.
Photosynthetic or Assimilatory roots :They have green chlorophyll pigments and capable of synthesizing their food e.g. Tinospira , Trapa , and Padostemum.
Primary Root : Direct prolongation of the radical, common in angiosperms, monocots and dicots.
Prop or Pillar roots :They
are stout , cylindrical , adventitious roots bearing bunch of branches
only at the apex. They grow and hang downwards and on reching the soil
produce normal adventitious roots e.g. Banyan.
Secondary root(s) : Lateral branches arising in succession from primary root.
Taproot : A well established and strong primary root, as in dicots, it may be fusiform, napiform, conical or tuberous.
Tertiary root(s) : Thinner branches that arise from secondary branches, found only in dicots.
Tuberous root :The swollen root has no fixed shape and is irregular in outline e.g. Mirabilis jalapa (Four o’clock Plant).
Stem : The upright part of the plant which grows from pumule of seed is called stem. It bears nodes , leaves and branches.
Axillary bud :The buds which are located in the axil of each leaf are called Axillary or lateral buds. These buds grow into branches.
Buds :The buds is a small compact structure and the shoot develops from it. Plumule is the first bud.
is very much reduced in this case .it is discoid in shape . It bears
large number of scale leaves. It possesses terminal bud in the centre
and gives rise to aerial shoot that produces flower e.g. onion. It
garlic several bublets (small bulbs or cloves) may be seen within a
large bulb. There arise from axillary buds and are capable of developing
into new plants.
Bulbil :A few plants propagate
by means of vegetative or floral buds which are called bulbils. They
germinate directly to grow into new plants e.g. oxalis , Pineapple,
Agave and Dioscorea.
Caudex :The unbranched , persistent main axis of a plant: it bears a cluster of leaves (crown) at the apex , e.g., plam trees.
Cladode : It
is a phylloclade with one or two intrerodes only .it resembles a leaf .
It arises in the axil of a much reduced scale leaf e.g. Asparagus and Acuteatus.
Climber :A weak stem attached to any neighbouring objects and thereby climbing up peas, gourds, vines etc.
corm is a short, vertical underground stem swollen with reserved food.
It is unbranched e.g. crocus, Gladilous, Amorphophallus, Colocasia and
Creeper :Weak stem creeping on the
ground and reforming at the nodes. It may be a runner, stolen, offset or
sucker, according to its varied nature.
Culm : Jointed stem with solid nodes, cut hollow internodes, found in clusters in certain monocosts-wheat, bamboo etc.
Erect aerial stem :Unbranched, cylindrical, erect and stout stem, often marked with scars of fallen leaves.
Forms of Stem
Internode : The length of the stem between two adjacent nodes is called internode.
Offset : It
is like a runner in all respects with the only exception that it is
comparatively thicker and bears a single daughter plant at its end
Phylloclade’s or cladodes :It is
branch which take the form and function of leaf. the true leaves are
reduced to spines . It is flattened leaf like e.g. opuntia and euphorbia
. it is cylindrical in shape in case of casuarinas.
Prostrate:A trailing stem lying horizontal on the ground surface.
is perennial, fleshy, underground, non-green stem. Nodes are marked as
scars bearing dry scale leaves in their axils. Branches and buds are
also present. Underground adventitious roots arise from them e.g.
Ginger, Turmeric and banana.
Runner :They are
slender prostrate branches. They have long intemodes which creep on the
ground. They bear roots at the nodes. The axillary buds form new
branches e.g. oxalis, strawberries, and Doob grass (Cynodon).
Special modifications of steam: The aerial steams vary in form as they as they are modified to perform special functions they are as follow:
is thread like slender and spirally coiled (spring like) structure
which develops from auxiliary bud. It helps the plant in climbing .the
tendrils are found in the axil of leaf and hold the support e.g.
Passiflora(passion flower) , Antigonon , Grapevine , Cucumber , Pumpkin ,
Stolon :It is a slender branch
arising from the base of main axis. It grows the horizontally for some
time and then arches to touch the ground. Its terminal bud gives rise to
a new shoot and roots, e.g. Mentha , Jasmine.
Sub-aerial modification :Stems
are normally weak, prostrate and touch the ground. They are buried
superficially in the soil. Aerial branches and adventitious roots
develop at the nodes. They may behave as independent plants when
detached. They are generally known as creepers. The modification are of the following types :
is like a runner but originates from the basal or underground portion
of main stem. It grows horizontally beneath the soil but soon comes out
upward obliquely bearing the leafy shoot. Suckars are shorter and
stouter then runner e.g. cotocasia, mint and chrysanthemum.
Terminal bud: The bud which remains at the tip and continues to grow indefinitely , is called Terminal or apical bud.
The stem, its branches, leaves, flowers and fruits constitute the shoot system of plant.
is hard sharp pointed needle like structure present in the exil of
leaf. It may bear leaves . they protect plant from browsing animal e.g.
Duranta , Citrus , Lyceum etc. .
tubers are swollen stems serving for storage of food and vegetative
propagation .The tubers have axillary buds at the nodes often called as
eyes e.g. potato.
Twiner :A climbing weak stem that winds about its support pale beans.
Underground modification of stem :some
perennial herbs develop their stem underground for the purpose of
perenation and storage of food. They helps in vegetative propagation.
They appear like roots but are distinguishable from them in having scale
leaves at the nodes and buds. The important types of modification are
Weak serial stem :stem trailing on the ground without rooting at the nodes e.g. purslane (Portulace oleracea) etc.
leaf is a lateral flattened structure borne at a node and initiate from
the shoot meristem or primordial and gradually enlarges. It usually has
a bud in its axil. Leaf contains chlorophyll hence it is the main
photosynthetic organ of the plant.
Parts of a leaf :The
basal part of the leaf where it is attached with the stem is called
leaf base. On either side of leaf base arise small leaf or scaly
structures known as stipules. Depending upon the presence or absence of
stipules, a leaf may be stipules or exstipular. In most of the leaf is
swollen and is formed pulvinus. It is responsible for movement.
Leaf stalk or petiole :In
some plants the leaves possess a very prominent stalk called petiole
for proper display of lamina. The petiole is generally rounded, groved
or may be angular.
Leaf blade or lamina :The
flattened expanded green portion of the leaf is called leaf blade of
lamina. The border of the leaf lamina is called leaf margin. The
lower portion where petiole combine with lamina is called lamina base.
The opposite end is termed apex. In the centre of lamina runs a
prominent raised ridge called midrib from which numerous side branches
arise called veins. The veins, further divide into finer branches and
they form a network. Veins form the skeleton of lamina and act as
channels for transport of food, water and minerals.
Leaf apex : The tip of the lamina is termed as leaf apex. It is of the following types :
Acuminate : The apex is long and tapering e.g. Ficus.
Acute : Apex is pointed but not stiff, e.g. chinarose.
Cirrhose : Having non-sensitive tendril like apices e.g. Banana.
Crenate : Margin is superficially rounded or obviously toothed e.g. Bryophyllum.
Dentate : Margin is with sharp spreading coarse indentations that are perpendicular to this margin e.g. cucurbita.
Emarginate : Rounded but with deep notch e.g. Bohinia.
Entire : When the margin is smooth and not dissected at any point e.g. banyan and mango.
Leaf bladder : Leaf
bladders are small specialized sacs which are found in the aquatic
plant Utricularia. The leaves are highly dissected and some become
modified to form these bladders. These modifications are to trap animals
for obtaining nitrogen.
Leaf modified into roots : In
the case of salvinia, three leaves are present at each node of stem.
Out of three, two remain as leaves while the third gets modified to form
Leaf pitchers : The whole outer lamina
of the leaf may be modified to form a large pitcher e.g. Dischidia,
Sarsacenia and Nepanthes. These modifications of the pitchers are meant
for capturing insects, and collecting water. Each pitcher is provided
Leaf spines : The part of leaf becomes changed into spines in order to protect the plant from grazing animal e.g. Opuntia and Acacia.
Leaf tendrils : Tendrils
are thread like structure which are capable of coiling around the
support. They may be whole leaf tendrils as in wild pea, leaflet
tendrils as in Pisum sativum, petiolar tendril as in Nepantnes, rachis
tendrils as in clematis and leaf tip tendril as in Glory lily.
Margins of Leaf lamina : Following are the various kinds of margins of leaves :
Modification of leaf : The
leaves or their parts may be modified to perform certain special
functions other than synthesis of food. The modifications are as follows
Mucronate : Apex pointed suddenly from almost rounded region e.g. vinea.
Multicostate reticulate : When there was more than one midrib arising from a single point e.g. cartor and Ipomoea.
Multicostate venation : In this case several veins run parallel to one another in a leaf e.g. wheat, corn.
Obtuse : Apex is rounded e.g. Banyan.
Parallel venation : When
the veins are parallel and do not form a network such a venation is
called parallel. It is characteristic feature of monocotyledons. It is
of two types :
Phyllodes : In the case of
Australian Acacia the leaf is bipinnate compound. The leaflets gradually
fall down and the rachis becomes flattened and green in colour to carry
Pinnately lobed : The margin is with incisions more than the size of tooth.
Reticulate venation : When
the veins are irregularly distributed to form a network, it is known as
tericular venation. It is characteristic feature of the dicotyledons.
It is of the following types :
Retuse : Rounded but slightly notched e.g. Pistia.
Serrate : When the margin is like teeth of a saw e.g. China rose and Rose.
Tendrillar : Apex long, drawn out and modified into a tendril.
Truncate : Almost flat e.g. Indian Saga Palm.
Undulate : When the outline is although smooth, but wavy e.g. Ficus and Ashok tree polyalthia.
Unicostate parallel : The
lamina has a single prominent midrib and from this arise lateral veins
which run parallel towards the margin e.g. Banana, Turmeric.
Unicostate reticulate : A leaf with a single main midrib or casta is called unicostate reticulate e.g. Eugenia (jamun) and Oleander (Kaner).
Venation : The arrangement and distribution of the veins in the leaf lamina is called venation. It is of the following type :
Flower : Morphologically
it is a shoot bearing nodes and modified floral leaves. Though all
flowers have some basic plan, these exhibit wide variation in size,
shape, colour and arrangement of floral parts.
Achlamydeous : Naked flowers, flowers that do not have sepals or petals.
Actinomorphic flower : Flower whose symmetry remains unchanged when it is cut into two halves through any vertical plane passing through the axis.
Aestivation : Arrangement
of sepals in calyx, petals in corolla or tapels in perianth in a floral
bud, it is an important diagnostic character and may be of the
Androecium : Third whorl,
composed of stamens or micro-sporophylls, that are regarded as male
organs of the flower. Each stamen is made of filament, anther and
Apocarpous (flower) : Having carpels separate from each other.
Bisexual flower : A flower containing both androecium and gynoecium.
Bract : Modified leaf associated with plant reproductive structures, from its axillaries a solitary flower or a cluster of flowers.
Bracteole : A small bract, especially if on floral axis.
Calyx : First or the lowermost whorl of green floral leaves called sepals.
Complete flower : Flower having all the four whorls (sepals, petals, stamens and carpels).
Corolla : Second accessory whorl of flower, consists of number of brightly coloured petals.
Dichlamydeous flower : Flower having both calyx and corolla.
Egigynous flower : Cup
shaped thalamus fused with ovary (inferior) so that other floral parts
arise on the top of the ovary e.g., apple, cucumber etc.
Flora pleno : Double flower, in which carpes have also become modified petals.
Floral diagram : Diagram of a flower in cross-section depicting the number and arrangement of floral parts.
Floret : Small flower, individual flower of an inflorescene.
Floribunolus : Flowering profusely.
Floriculture : Culture of flowering plants.
Floriculus : A floret.
Florid : Flowery, ornate.
Floriferous : Flower bearing, blooming freely.
Floristics : Study of taxonomic identification and listing of all plant species present in a community.
Florivorous : Feeding on flowers.
Florula : Plant (flowers) that grow in small confined habitat e.g. lotus in a pond.
Flower bed : Strip of well prepared and manured land, usually in a garden or farm, for growing flowers.
Gynoecium (pistil) : Fourth or female whorl, comprising of carpels or megasporohylls; each pistil is made of three parts – ovary, style and stigma.
Hermaphrodite : A flower possessing both stamens and carpels.
Hypogynous flower : The ovary superior is situated on torus, above all the other floral parts e.g. mustard, tomato etc.
Imbrecate : Overlapping of one or more sepals or petals over adjoining ones e.g. gul mohur etc.
Incomplete flower : Flower lacking one or more, of the four whorls.
Inflorescence : A flower cluster; arrangement of flowers on the axis.
Nectar : Sugar containing fluid secretion of nectarines.
Neuter (sterile) flower : One that does not have any functional stamen or carpel.
Pedicel : Stalk of the flower (solitary or part of an inflorescence).
Peduncle : Main axis of inflorescence on which flowers are borne.
Perigynous flower : The thalamus forms cup shaped structure around the ovary and bears sepals, petals and stamens e.g. rose etc.
Pistillate : Having pistil (but no stamen), female unisexual flower.
Pistillode : A pistil lacking ovule.
Placenta : Plant surface bearing sporangium (ovules).
Receptacle (thalamus) : Tip
of pedical that continues as an enlarged axis and bears all other
floral apprendages (organs). A typical flower consists of four different
types of floral leaves – calyx, corolla, androecium and gynoecium.
Staminate : Male unisexual flower.
Staminode : A stamen with no functional anther.
Syncarpous : Gynoecium having carpel united in a compound ovary.
Tapetum : Layer of nutritive cells surrounding the spore mother cells in sporangium in higher plants.
Tetracyclic flower : Having all the four whorls.
Thalamus : Suppressed, swollen end of a floral axis on which the floral leaves are borne.
: When one margin of sepals or petals overlaps that of the next one and
the other margin is overlapped by third one, twisting may be clockwise
or anticlockwise e.g. rose etc.
Unisexual flower : Flower having either androecium or gynoecium.
Valvate : When
the members of the whorl are in touch with each other by their margins
or lie very close to each other but do not overlap e.g. bullock’s eye,
Vercillary : Flower with five petals,
of which the posterior one is the largest, almost covering the two
lateral petals which in turn nearly overlap the two anterior or the
smallest petals – bean, pea etc.
Zygomorphic flower : Exhibiting bilateral symmetry.
Floral symbols :
C4 Four fused petals in a corolla
(Inferior) position of ovary
G (Superior) position of ovary
K4 Four sepals in the calyx
( ) Cohesion of a whorl
Fusion of two whorls
Anemophily : Wind
pollinated, anemophilous flowers are unisexual, with anthers and stigma
exposed and pollen grains are small, smooth and dry and are produced in
enormous number (a single flower of bhang, Cannibis satira produces
over 500000 pollen grains) e.g. coconut palm, date palm, maize etc.
Autogamy (endogamy) : Self-fertilisation fusion of male and female gametes derived from the same individual flowers (pea, rice, wheat etc.).
Chiropterophily : Bat
pollination – bats are flying (nocturnal) mammals; the flowers they
visit, are large with strong scent; the bats move swiftly and transport
pollen over long distances (upto 30 km).
Cross-pollination : Transfer
of pollen from anthers of flower on one plant to the stigma of a flower
on another plant; it requires assistance of an abiotic – wind
(anemophily), water (hydrophily) or biotic agent insects (entomophily),
bird (ornithophily), bats (chiropterophily).
Double fertilization : A
unique phenomenon in flowering plants where union of egg and one of the
sperm nuclei as also the fusion of second male nucleus with polar
nuclei takes place.
Embryo (In plants) : Partly
developed sporophyte which in angiosperms in protected within a seed and
if differentiated into a radical, plumule and cotyledons. The product
of conception up to the third month of human pregnancy.
Embryo sac : The
female gametophyte of flowering plants, consisting of a sac-like
structure inside the ovule in which six haploid cells and two haploid
nuclei are found.
Embryoculture : In vitro growth of isolated plant embryos on suitable culture medium.
Embryogeny (embryony) : Process of formation of embryo from a fertilized egg cell.
Embryology : Study of development of the organism from the zygote or fertilized egg.
Embryonate : Containing an embryo.
Entomophily : Insect
pollination, insects visit flowers to gather nectar and pollen, These
insects inadvertently transfer pollen from one flower to another bees
are the chief pollinators besides butterflies and moths-clovers,
cucurbits, mustard, safflower, sunflower and some pomaceous fruit trees
give significantly higher yields if bees are around for pollination. Fig
trees (Ficus carica) require certain insect species (Blastophaga) to
effect pollination, while orchids (Ephrys spp.) require males of a
particular moth who are misguided and consider orchid flower as a female
moth and go for (Psuedo) copulation that brings about pollination.
Fertilisation : Fusion of male and female gametes of the same species to give rise to a zygote which subsequently develops into a new organism.
Geitonogamy : Marriage between neighbours : self-pollination and fertilization of one flower by another on the same plant.
Hydrophily : Rare
phenomenon that occurs in totally submerged marine plants –
ceratophyllum demersum, vallisneria spirals, eel-grass, Zostera marina
Ornithophily : Bird pollination – birds
visit various (osithophilous) flowers to collect nectar and in the
process, also transfer pollen from one flower to another.
Pollination : Transfer
and deposition of pollen on the stigmata surface of the flower, it may
be self pollination (autogamy, geitonogamy) or cross pollination
(allogamy), assisted by abiotic (water, wind) or biotic (insect, birds,
bats etc.) agencies.
Self-pollination : Transfer
of pollen from the stamen of a flower to the stigma, either on the same
flower (autogamy) or on another flower on the same plant (geitonogamy);
it leads to self fertilization, also known as inbreeding.
Fruit : Fruit
is a ripened ovary which is usually formed after fertilization. After
the act of fertilization ovary forms fruit and ovules change into seeds.
The fruit is also known as Eucarp. Some fruits are
formed without fertilization and do no bear seeds. These fruits are
described as a parthenocarpic fruits e.g. Banana and Grapes.
Aggregate fruits : They
are also produced from a single flower, but gynoecium is bi-, tri- or
polycarpellary and apocarpous. The ovary matures to form a simple type
of fruit called fruitlet. Thus the whole fruit is
collection of such fruitlets corresponding to the number of carpels in a
flower e.g. buttercup, calotropis, etc.
Berries or baccate fruits : These
are simple succulent fruits derived from superior or inferior ovary.
Mostly they are many seeded but date is a single seeded berry fruit
having membranous endocarp. Endocarp is generally edible in berry
Classification of fruits : The fruits are classified according to the nature of pericarp and condition of gynoecium as follows :
Composite fruits : Fruits formed from an inflorescence are called composite fruits, e.g. Fig, mulberry, etc.
Drupe or Stone fruits : These
are also simple succulent fruits in which the pericarp is
differentiated into epicarp, mesocarp and endocarp like berries. They
differ from berries in having hard and stony endocarp around the seeds,
hence they are also known as stony fruits. The mesocarp
is fleshy and edible in mango or fibrous in coconut or dry in Almond.
The epicarp is thin and not edible. They are derived from simple or
compound, inferior or superior pistil. The drupes of cherry, peach, plum
are derived from monocarpellary superior pistil while zizyplus develops
from compound and superior ovary. In these drupes, the endocarp is
stony, mesocarp is fleshy and edible and epicarp forms outer skin of the
fruit. The coconut is a fibrous drupe and develops from compound
superior pistil. It has stony endocarp, fibrous mesocarp and membranous
epicarp. The air is enclosed in the fibrous mesocarp which makes the
fruit fit for floating on water surface. The white endosperm of the seed
is the edible portion which contains milk of coconut.
Fleshy or edible fruit : They usually remain succulent and juicy e.g. drupe, berry, pepo, hesperidium and pome.
Hesperidium : These
are citrus fruits which develop from polycarpellary, syncarpous,
superior ovary with axile placentation. Epicarp and mesocarp are fused
to form outer skin or rind of the fruit and are easily separable. The
endocarp is membranous and surrounds the loculi. The edible portion of
the citrus fruit is juicy hairs which are the outgrowth of inner side of
membranous endocarp e.g. citrus (orange and lemon etc.)
Pepo : It
is a special false berry fruit and is derived from tricarpellary
syncarpous ovary with parietal placentation. It is many seeded. The
seeds are like typical berries and do not separate from the placentae on
ripening. The mesocarp, endocarp and placentae are edible. The mesocarp
is not separable from rind. The outer thick rind is formed by the
fusion of thalamus with epicarp e.g. pumpkin, lagenaria, water melon and
Simple fruits : They are formed on the
basis of one fruit from one flower. Thus simple ovary on ripening forms
the single fruit e.g. Mango, peech, plum.
True and False fruits : The
true fruits develop from the ovary. In these fruits the ovary wall
changes into fruit wall or pericarp which surrounds the seeds. The
pericarp is usually differentiated into three layers – epicarp, mesocarp
and endocarp and any layer may become edible in fleshy fruits. But in
some fruits the other floral parts like thalamus and basal portion of
perianth, bracts etc. may also be fused with pericarp to form the main
edible portion of a fruit. Such fruits are false fruits or pseudocarp e.g. Apple, pear etc. Apple and pear are false fruits. Almond and orange are true fruits.
Functions of fruits
- Protection of seeds in the early stages till they become fully mature.
- Dispersal of seeds.
- On their decay provide raw material for the benefit of new seedling.
- Many fruits are consumed by human beings as food and is source of glucose and pectin.
Seed : A
fertilized ovule consisting of an embryo surrounded by food store for
nourishment during germination, with an outer hard coat (testa), it
forms a new plant (seeding) on germination.
Cotyledon : First leaf of the embryo of seed plants.
Epocotyl : Embryonic plant stem between plumule and cotyledons.
Funiculus (funicle) : Short stalk of an ovule by which seed is attached to fruit.
Hilum : The scar on the seed surface from where funiculus has been detached.
Hypocotyl : Portion of the embryonal axis between radical and point of attachment of cotyledons.
Micropyle : A minute pore in the integument at the tip of an ovule, persists in the seed as an opening between hilum and redicle.
Plumule : Shoot tip, primary bud of a plant embryo.
Radicle : Embryonic root of a flowering plant.
Seed coat : The envelope that covers the entire seed except for a tiny pore (Micropyle).
Seed dispersal : Seeds are dispersed by wind, water or by bursting of explosive fruits.
Testa : Outer
seed coat developed from integument of the ovule, in bean seed. It is
thick, smooth and variously coloured, while inner coat is thin, white
and often difficult to separate from testa.