Psilotum nudum (L.) P. Beauv., 1805
|Common Names:||Whisk Fern|
This is a vascular plant without roots. The rhizome is mycorrhizal and bears rhizoids. The aerial stems are erect but becoming pendent in large plants, 10-50 cm long, angular and dichotomously forked. Leaves are small, scale-like, 1-2 mm long, scattered and vainless. The sporangia are 3-lobed and borne on the axils of the leaves. Spores are bilateral.
Widely distributed throughout the tropics and subtropics.
This is a terrestrial plant but more often is epiphytic.
The spores are of the same size, germinating extremely slowly in darkness underground into cylindrical gametophytes that are about 2 mm in diameter. The gametophytes are sometimes forked and covered with numerous rhizoids. Growth depends on the presence of an endophytic mycorrhizal fungus. The sex organs develop from the surface of the gametophyte. Once the sperms from the antheridia fertilise the eggs in the archegonia, the zygotes develope into the sporophytes.
For an account of the life history of atypical fern, see Pyrrosia piloselloides.
Psilotum nudum is reputed to have laxative properties. It can also make an attractive ornamental plant.
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