The Status of Gyroweisia in North America

Abstract

Gyroweisia has in fact no valid status anywhere. Limpricht' complained of the several names that Schimper had at different times applied to this genus, but did not perhaps take the trouble to verify his references. Thus I have been unable to find Weisiopsis published by Schimper as a genus, with priority, if Limpricht were right. Limpricht's source was presumably Schimper's own statement,2 but this speaks only of a subgenus Weisiopsis. In the Bryologia Europaea I find no such name either as genus or subgenus under plate 28 or in the text referring to it, but only as a subgenus in the index of Vol. I, page VII, which is apparently from the later date of 1851. The case is different with Weisiodon, which was entirely adequately published as a genus3 and by all the rules of priority should supplant the later Gyroweisia. Its type-species was the Weisia reflexa of Bridel occurring in southern Europe and northern Africa. Schimper's reason for changing the name to Gyroweisia was the inclusion of the European Gymnostomum tenue of Schrader, which he rightly recognized to be closely related to the other, but which has no peristome teeth. Both have a prominent persistent annulus-hence the name Gyroweisia, Weisiodon being no longer appropriate. But it should be obvious that a generic name need not be a generic description, cannot in fact remain one with the growth of knowledge of forms and their natural relationships.4 Priority demands the retention of Weisiodon, if the genus itself is worthy of retention. As a matter of fact, like many others, it is not particularly well understood. Engler & Prantl's Natiirliche Pflanzenfamilien includes in it for the first time a number of exotic species, and their figure taken from a portion of the plate of Weisia reflexa in Bryologia Europaea has inspired still further additions. As to North America, the inclusion of this genus in its moss-flora rests in the first place upon number 21 of Drummond's Musci Americani named Gymno-