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EQUISETUM
OCCURRENCE AND DISTRIBUTION OF EQUISETUM
Equisetum (L. equus=horse + seta= bristle) is popularly known as horsetail or scouring rushes.
There are about 25 species.
They are found mostly in North temperate and tropical zones.
In India four common species are E. arvense, E.diffusum, E. palustre and E. ramosissimum .
EXTERNAL FEATURES
HABIT :
The plant body of Equisetum consist of-
Aerial part (Herbaceous, annual).
Underground rhizome part ( perennial, horizontal, branched and creeping in nature).
Both are with nodes and internodes.
Majority of the species are small with a size range in between 15 and 60 cm in height and 2.0 cm in diameter.
E. scripoides (smallest).
However some species grow up in higher heights [e.g., E. giganteum, E. telmateia, E. ramosissimum], though their stem are relatively thin showing vine-like habit and climb over adjacent forest trees.
HABITAT:
Generally found in wet or damp habitats, along the banks of streams or irrigation canals (E. debile, E. palustre).
However, some species are adapted to xeric condition (e.g., Equisetum arvense).
Some species of Equisetum are indicators of the mineral content of the soil in which they grow.
Some species accumulate gold, thus they are considered as ‘gold indicator plants.
In Equisetum, silica is deposited on the outer wall of the epidermal cells giving the characteristic rough feeling, thus it provides a protective covering against predators and pathogens.