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Africa south of the Sahara present, Asia present, Asia-Tropical: New Guinea present; Sumatera (Sumatera present), Himalayas present, N. Thailand present, New Zealand present, North temperate Eurasia present, S. India present, eastern temperate and subtropical N. America present
North temperate Eurasia, in Asia south to Himalayas; eastern temperate and subtropical N. America; Africa south of the Sahara; S. India; N. Thailand; in Malesia: Sumatra and New Guinea; New Zealand. Two species, northern and southern, the former with geographically distinct subspecies.


Base chromosome number 35; many observations in north temperate regions, all diploid.


This genus, as restricted by Ching but excluding his T. grisea, is the temperate counterpart of Cyclosorus (in the restricted sense here adopted). Both are rhizomatous ferns growing in open fresh-water swamps. They also agree in having fronds with unreduced basal pinnae and in bearing flat scales on lower surface of costae, a character uncommon in the family. In the present work, Cyclosorus is associated with Ampelopteris and Mesophlebion; from these three Thelypteris differs in (a) capitate hairs on sporangia, (b) lack of red glands at the ends of hairs on sporangium-stalk, (c) chromosome number 35, (d) basiscopic vein always from costule, not from costa. But I suggest that Thelypteris is nearest to this group of genera.
Ching included Nephrodium griseum BAK. (see ) as a species of his restricted Thelypteris. The type of this is a specimen at Kew from Cochin which resembles T. palustris in its forked veins but in little eise. Beddome wrote a note on it in his own Herbarium (now at Kew) and suggested that it was probably an abnormal form of Lastrea calcarata var. ciliata (Trigonospora ciliata of the present work) but in my opinion it is an abnormal form of a species of Pseudocyclo sorus. The best account of the genus in the northern hemisphere is by Fernald, l.c.


Fernald 1929: pp. 27-36. – In: Rhodora: pl. 179-180
Holttum 1968 – In: Taxon: 330
A.F. Tryon 1971 – In: Rhodora: 444
Ching 1963 – In: Acta Phytotax. Sinica: 297
Schmidel 1971 – In: Blumea: 28