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BOTANY Higher Secondary Second Year - Textbooks Online

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1.3.6. EUPHORBIACEAE – the castor family<br />

Systematic position<br />

Class: Dicotyledonae<br />

Sub-class: Monochlamydeae<br />

Series: Unisexuales<br />

Family: Euphorbiaceae<br />

General characters<br />

Distribution<br />

Euphorbiaceae includes more than 300 genera and about 7,500 species.<br />

It is world wide in distribution, but particularly well represented in Africa<br />

and South America. In India, it is represented by more than 70 genera<br />

and about 450 species.<br />

Habit<br />

This family includes a large number of annual herbs (eg. Phyllanthus<br />

amarus) or shrubs (eg. Ricinus communis) or trees (eg. Phyllanthus<br />

emblica). In several species of Euphorbia, the stem is modified to perform<br />

photosynthesis. This modified stem is called cladode and it resembles<br />

cactus. eg. E. tirucalli and E. antiquorum (Sadhurakkalli). This family<br />

shows a great range of variation in vegetative and floral characters. Almost<br />

all the plants have latex which is either milky or watery.<br />

Root<br />

A branched tap root system.<br />

Stem<br />

Aerial, erect or prostrate (eg. E. prostrata), cylindrical, branched,<br />

solid or hollow (eg. Ricinus communis), usually contains milky latex (eg.<br />

E. tirucalli) or watery latex (eg. Jatropha curcas).<br />

Leaf<br />

Stipulate or exstipulate, petiolate, alternate (eg. Ricinus communis),<br />

simple, entire or deeply lobed or trifoliately compound (eg. Hevea<br />

brasiliensis) and with unicostate or multicostate reticulate venation. The<br />

stipules are modified into a pair of spines (eg. E.splendens) or glandular hairs<br />

48

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