Euphorbiaceae and Urticaceae- Introduction

on

Euphorbiaceae
(Spurge family)

Jatropha


Plants of this family are mostly shrubs (Ricinus communis, Jatropha gossypifolia) or trees (Emblica officinalis), or sometimes herbs (Phyllanthus niruri), or climbers (Tragic involucrata); some are xerophytic (many species of Euphorbia) or cactus like or phylloclades (stem becomes flattened and leaf-like); some are marshy (Coperconia); usually the plants contain milky sap or latex.
Inflorescence is highly variable from a raceme (Croton), a spike (Acalypha), a dichasium (Jatropha), or even the flowers are solitary axillary (Phyllanthus asperulatus); but in majority of cases, as in Euphorbia, the inflorescence is a cyathium. 
Each cyathium contains terminally a single naked female flower. usually represented by a tricarpellary gynoecium. The female flower is surrounded by a cup-like involucre formed by 4 or 5 connate sepalled bracts. In the axil of each bract develops a group of stamens in a scorpioid manner. Each stamen represents a naked male flower because it is a jointed structure which indicates that its upper portion is a filament bearing the anther and its lower portion represents the pedicel of the male flower bearing stamen. On the rim of the cup-like involucre are present nectar-secreting glands. Glands are oval or crescent shaped and often brightly coloured. The cyathium appears like a single flower but actually it is an inflorescence.
Fruits and seeds: Fruit usually a capsule, but sometimes a drupe. Seeds endosperm, oily, with a knob-like caruncle (Ricinus communis); embryo straight.
Pollination: Cross-pollination is necessary because of unisexual flowers. Certain characters (coloured bracts, well-developed nectaries and glands) also favour insect pollination in some plants.



A family of about 300 genera and 7500 species, Euphorbiaceae are cosmopolitan in distribution. They are abundant in both tropical and temperate regions and not well represented in arctic regions. Over 60 genera and 350 species have been reported from India. Selected Indian genera are: 
    • Croton, 
    • Euphorbia, 
    • Hevea, 
    • Jatropha, 
    • Manihot, 
    • Phyllanthus and 
    • Ricinus.

Economic Importance

Several plants of high economic importance belong to Euphorbiaceae, such as Hevea brasiliensis (the main commercial source of rubber), Ricinus communis (the source of castor oil), Manihot esculanta (the source of cassava or tapioca), Emblica officinalis (the source of amla), Euphorbia pulcherrima (the famous ornamental Poinsettia) and Codiaeum (the popular ornamental plant with variegated leaves, often incorrectly called 'croton'). However several Euphorbiaceae are poisonous, causing sickness or death if ingested, or dermatitis if juice contacts the skin. even the rainwater dripping from certain plants is enough to cause dermatitis and therefore should be handled with utmost care. Some of the specific uses are:

Ornamental plants:
    • Acalypha ciliata
    • A. hispida
    • A. wilkesiana
    • Codiaeum variegatum (plants with variegated leaves)
    • Croton tiglium (croton)
    • Euphorbia antiquorum (tidhara sehund)
    • E. neriifolia (sehund)
    • E. pulcherrima syn. Poinsettia pulcherrima (Poinsettia with red, pink and white floral leaves)
    • E. splendens (crown-of-thorns with bright red bracts)
    • E. tirucalli (milk bush)
    • Jatropha hastata
    • J. gossypifolia
    • J. podagrica
    • J. panduraefolia
    • Trewia nudiflora (false white teak)
Oil plants: 
    • Croton oil obtained from seeds of Croton tiglium (jamalghota) is used as a powerful purgative,
    • castor oil obtained from the seeds of Ricinus communis is mainly used as a vegetable oil and also as a mild laxative, as a lubricant and in paint, varnish and plastic industries,
    • Jatropha oil obtained from the seeds of Jatrophs curcas, is used as a purgative and also in skin diseases, in rheumatism, and also in manufacture of soaps, lubricants, candles, etc.
    • Tung oil, obtained from the seeds of Aleurites ford, A. moluccana and A. montana is used in preparing paints, varnishes, linoleum, Indian ink and also in waterproofing the paper, wood, etc.
Rubber:
    • Over 98% of total natural rubber produced in the world, is obtained from the coagulated latex of Hevea brasiliensis.
    • Manihot glaziovii (Manicoba rubber) is the another rubber-yielding plant of this family.
Cassava or Manioc: 
Tuberous roots of Manihot esculenta (cassava) are rich in starch (Arrowroot) and used for preparing bread, biscuits and other foodstuffs. Bitter cassava contains hydrocyanic acid (HCN) and must be used with due care.

Medicinal plants:
    • Emblica officinalis syn. Phyllanthus emblica (amla) fruita are rich source of vitamin C, used in treating scurvy, in preparing shampoos and also in making hair dyes (bark and leaves of this tree are used in tanning),
    • Castor (Ricinus communis) oil is a valued purgative,
    • Jatorpha gosssypifolia leaves are used in eczema and roots in leprosy and snake bite,
    • Entire plant of Synadenium grantii is used as a stimulant of nervous system,
    • Croton cascarilla and C. elateria bark is used as a tonic,
    • The drug Euphorbium obtained from the latex of Euphorbia resinifera, is used as a purgative,
    • Mallotus philippinensis (kamela tree) fruits are used as anthelmintic.
Dyes:
    • Kamela dye, obtained from the fruits of Mallotus philippinensis  is used for dyeing wool and silk,
    • Blue dye, obtained from the bark of Jatropha curcas, is used for dyeing fishing nets,
    • Purple dye, obtained from the bark of Chrozophora tinctoria is used for textile industry,
    • Red dye is obtained from the roots of Kirganelia reticulata.
Timber Plants:
Valuable timber is used for packing cases, tea boxes, veneers, plywood, match industry and several other similar purposes, is obtained from 
    • Aporosa dioica
    • Bischofia javanica
    • Drypetes roxburghii
    • gelonium multiform
    • Hemicyclia andamanica
    • H. elate
    • Hura crepitans (sandbox tree)
    • Trewia nudiflora (False white teak)








Urticaceae
(Nettle family)


Plants of this family are mostly herbs (Urtica), infrequently shrubs (Maoutia, Boehmeria) or rarely small trees (Laportea crenulata); without latex but with watery sap; a few are climbers; stinging hair present in several genera (Urtica, Urera), are long hollow cells with silicified tips which penetrate the skin like a fine needle; stinging hair usually absent in several genera (Piles, Elatostema, Boehmeria, Maoutia, Parietaria, Cecropia); epidermal cells usually contain cystoliths.
                            A family of about 45 genera and 1060 species, Urticaceae are distributed in both tropical an temperate regions. About 12 genera and 100 species have been reported from India, mainly distributed in Assam, West Bengal, Kashmiri and sub-Himalayan regions. Selected Indian genera are: 
    • Laportea, 
    • Boehmeria, 
    • Pouzolzia, 
    • Sarchochlamys, 
    • Urtica, 
    • Girardinia and 
    • Elasostema. 
    • Urtica (stinging nettle) has sharp, stinging hair which penetrate in the skin of animals coming in their contact and cause sharp burning pain for hours.

Economic Importance
The family is of little economic importance as under:
    • Fibre (ramie) obtained from the inner bark of Boehmeria Nivea, is perhaps the longest and most silky of all vegetable fibres. It is used for cordage, ropes, etc. Fibres obtained from Maoutia puma and Gigardinia zeylanica are also used for similar purposes.
    • Bank notes are manufactured from the paper pulp made from the tough and silky fibres of Boehmeria nivea.
    • Ornamental plants belong to several species of Pilea, Pellonia, Soleirolia and Urera.
    • Young tops of Urtica are cooked and eaten like spinach.
    • Fruits of Debregeasia hypoleuca are edible.








Comments

Post a Comment