This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
This genus differs from the last in its cup-shaped involucre, and its long filiform receptacle. About eighty species are found in temperate and tropical countries. The derivation of the name is variously explained, but all of the explanations are open to doubt.
1. T. radicans. Fronds 6 to 12 inches high, pellucid, bi-or tri-pinnatifid, rachis winged. Stipes 2 to 6 inches, stout and wiry. This is very rare, and the only native species. It is found in Wales, and in a few localities in Ireland, in the vicinity of streams or waterfalls.
The members of this and the foregoing genus are not suitable for open-air culture except under quite peculiar conditions,