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Friday, 30 January 2009

FAMILY OF THE WEEK: SOLANACEAE





FAMILY OF THE WEEK: SOLANACEAE (NIGHTSHADE FAMILY)
A large family with over 2000 species worldwide. In India there are 15 genera and 88 species. Many species are cultivated while others occur chiefly in Himalayas and southern and eastern parts of India.
Vegetative characters:
They are mostly annual or perennial herbs, sometimes shrubs or small trees and rarely climbers. The stems are prickly or spinous, the spines are modified branches. The vascular bundles are bicollateral. Underground tubers are found in Solanum tuberosum. The leaves are alternate,exstipulate, simple,entire, lobed or pinnatified. In the inflorescence portion the leaves often become subopposite or opposite.
Inflorescence and flowers:
Often cymes which are lateral, axillary or terminal. In some species of Solanum they are extraaxillary appearing to arise from the middle of an internode. Very frequently they are solitary and axillary as in Datura and Nicardia and rarely clustered as in Withania. The bracts and bracteoles are absent.
The flowers are actinomorphic or sometimes zygomorphic, bisexual, pentamerous and hypogynous. The calyx is five lobed or five partite and usually persistent and much enlarged in fruit. The corolla is gamopetalous and funnell shaped(Datura) campanuloate(Physalis) or rotate(Solanum) The limb is usually five lobed or rarely ten lobed as in Datura and the lobes are folded contorted or valvate. The stamens are usually five,epipetalous on the corolla tube and alternate with the lobes. They are commonly of unequal heights. The anthers are ovate or oblong, sometimes connivant into a cone as in Solanum, dithecous,introrse and dehiscing by longitudinal slits or by apical pores.(Solanum)
Thhe gynoecium is typically bicarpellary and syncarpous. The ovary is superior and bilocular with axile placentation.The style is linear and the stigma is capitate or shortly lobed.
A hypogynous nectariferous disc is usually present at the base of the ovary.
Fruits and seeds:
The fruit is a berry which is sometimes (Physalis)enclosed within an inflated bladder-like calyx or capsule. The seeds are numerous, compressed, discoid or subreniform, endospermic and with a curved or straight embryo.
Pollination and dispersal:
Conspicuous flowers and nectariferous disc favor insect pollination. Solanum tuberosum is devoid of nectar and is scarcely visited by insects. Here usually self pollination occurs by the style curving backwards to touch the anthers.
The seeds are usually dispersed by birds and animals.Species of Datura,Atropa and Hyoscyamus are dispersed by water.
Examples:
Solanum tuberosum (Potato, Batata)
Solanum melongena (Egg plant,Brinjal,Baingan,Wang) Lycopersicon esculentum(Tomato)
Capsicum annuum
(Chillies, Mirch)
Nicotiana tobacum
(Tobacco)
Atropa belladonna
(Belladonna)
Hyoscymus niger
Datura stramonium
Withania somnifera
(Ashwagandha)
Withania coagulans (Indian rennett)
Petunia

Wednesday, 21 January 2009

FAMILY OF THE WEEK: SCROPHULARIACEAE


Rhamphicarpa

Verbascum chinens

Lindernia ciliata

FAMILY OF THE WEEK: SCROPHULARIACEAE
This family is cosmopolitan in distribution but most abundant intemperate regions. In India it is represented by 57 genera and 350 species occurring chiefly in Himalayas.
Vegetative characters:
Mostly annual or perennial herbs, sometimes shrubs (Veronica) or rarely trees(Wightia). Certain members are aquatic(Limnophila) or marsh (Departrium and Herpestis) Some are chlorophyll containing hemiparasites(Pedicularis and Striga) or parasites without chlorophyll as Lathraea.
Usually the lower leaves are opposite and upper alternate.They are simple exstipulate entire or pinnately lobed or incised.
Inflorescence and flowers:
Variable but commonly racemose or spicate. Sometimes cymose or axillary solitary.The bracts and bracteoles are usually present.
The flowers are perfect, hermaphrodite,zygomorphic or sometimes as in Verbascum nearly actinomorphic and hypogynous.The calyx is deeply five lobed or divided, persistent, imbricate or valvate. The corolla is gamopetalous and the limb is usually free and more or less bi-lipped.Commonly five stamens are fertile and the fifth is reduced to a staminode or is completely absent.The stamens are epipetalous. the anthers are dithecous but occasionally the two cells are unequal or only one cell is present. The gynoecium is bicarpellary and syncarpous with a superior bilocular ovary. The style is simple and the stigma is capitate, bilobed or bi-lamellate.
An annular or cup shaped nectariferous disc is present at the base of the ovary which is sometimes bilobed.
Fruits and seeds:
The fruit is a capsule or rarely a berry. the seeds are small with a fleshy endosperm and straight or slightly curved embryo.
Pollination and dispersal:
The flowers are adapted for insect pollination. The seeds are dispersed by water, birds or animals.
Examples:
Antirrhinum majus (Snapdragon)
Digitalis purpurea (Common foxglove)
Linaria vulgaris
Verbascum chinens
Rhamphicarpa
Lobelia nicotianifolia(Ran Tambaku)
Lindernia ciliata

Thursday, 15 January 2009

FAMILY OF THE WEEK: SAPOTACEAE





Achras sapota

Mimuseps elengi

FAMILY OF THE WEEK: SAPOTACEAE

In India there are 10 genera and 52 species occurring mostly in North Eastern and Southern India.

Vegetative characters:

They are trees or shrubs with young parts often rusty tomentose. The plants contain a milky juice. The leaves are alternate or rarely subopposite, simple, entire,petioled and coriacious and leathery. The stipules are usually absent.

Inflorescence and flowers:

The flowers are solitary or in cymose clusters in the leaf axils. They are bisexual, actinomorphic and hypogynous. The calyx has four to eight sepals which are united at the base. They are arranged in two or one series. The corolla is gamopetalous but the corolla tube is shorter than the calyx tube. The corolla lobes are usually as many as the calyx lobes and alternate with them and sometimes twice as many as the calyx lobes. The petal lobes are imbricate in bud.

The stamens are inserted upon the corolla tube. They are usually as many as the corolla lobes and opposite to the corolla lobes. Sometimes the stamens are two to three times as many as the corolla lobes and then they are two or three seriate. The outer stamens are sometimes reduced to staminodes as in Mimusops. The filaments are usually short. The anthers are oblong lanceolate, dithecous and extrorse. The connective is often produced beyond the anthers. The gynoecium has two to eight syncarpous carpels. The ovary is superior with as many locules as the number of carpels. The style is one, often apically lobed.

Fruits and seeds:

The fruit is one to eight seeded berry. Latex sacs are also present in the inner pulp of the berry. The seeds are often compressed with a crustaceous testa. The embryo is straight.

Pollination and dispersal:

Pollination is by insects. Fruits are distributed by birds and animals and water currents.

Examples:

Achrus sapota (Sapodilla plum)

Manilkara hexandra

Madhuca indica

Mimuseps elengi (Bakul)

Friday, 9 January 2009

FAMILY OF THE WEEK: SAPINDACEAE


Schleichera oleosa (Kusam)


Sapindus


Sapindus

FAMILY OF THE WEEK: SAPINDACEAE ACERACEAE(MAPLE FAMILY)
Large family represented in India by 24 genera and 72 species occurring in the tropical eastern Himalayas and western peninsular India.
Vegetative characters:
The members of the family are trees or shrubs or sometimes vines. The stems show peculiar secondary growth in thickness.
The leaves are alternate or rarely opposite (Acer), usually pinnately compound, sometimes simple (Cardiospermum), palmately lobed and veined (Acer) or digitate (Aesculus). They are exstipulate but occasionally stipulate as in Melianthus. The latex or resin cells are often present in the leaves.
Inflorescence and flowers:
Racemose inflorescence with minute flowers or unilateral cymes in panicles. The flowers are mostly polygamo-dioecious. They are zygomorphic or occasionally actinomorphic, tetra or pentamerous and hypogynous.
The calyx is composed of four or five sepals which are free or variously connate, often unequal and valvate or imbricate in bud.
The corolla is of four to five free petals but usually there are four petals and the place of fifth petal is vacant.
The androecium has typically eight or ten stamens or sometimes less as in Aesculus.
An annular or unilateral disc is often present between the petals and the stamens.
The gynoecium is usually tricarpellary and syncarpous. The ovary is superior.
Fruits and the seeds:
The fruit is capsular or it is indehiscent and entire or lobed as in Sapindus. Sometimes the fruit is a double Samara as in Acer or nutlike as in Litchi.
The seeds are globose or compound, often arillate, endospermic or nonendospermic with often plicate or spirally convolute embryo.
Pollination and dispersal:
The flowers are often protandrous and pollinated by insects. Flies and humble bees are the chief pollinators.The fruits of Dodonia and Acer are blown to long distances by strong winds. The dispersal also takes place by birds and animals in many genera.
Examples:
Litchi chinensis
Sapindus mukorossi (Soapnut tree, Ritha)
Sapindus laurifolius Acer saccharinum (Sugar Maple)
Aesculus hippocastanum (Horse chestnut)
Schleichera oleosa (Kusam)
Dodonia viscose (Vilayati Mehandi)
Nephelium lappaceum (Rambutan)