Have we this genus in North America ? This depends somewhat on the point of view. I think we have here a moss which in Europe passes for a Hymenostomum. HYMENOSTOMUM R. Br. in Trans. Linn. Soc., 18I9. The following is the historical view of this genus drawn up by Prof. Limpricht in Laubmoose, I, p. 223, 224: t Hymenostomum (membrane-mouth or-orifice), founded on Gymnostosmum microstomum Hedw., is characterized by the author as a natural genus not merely by reason of characteristic external appearance but by reason of the structure of the capsule. The authors of Bryologia Germanica (1823) emphasize its affinity with Weisia viridula, and they include besides H. rutilans (Hedw.), also H. squarrosum Bryol. Germ., H. obliquum N. v. E., H. brachycarfon Bryol. Germ., H. subglobosumn Bryol. Germ., and H. crisfatum Bryol. Germ.; however the last species is withdrawn again in I83I by the authors in Bryol. Germ., i . 2. p. 33. Huebener in 1833 considers H. obliquum and .H. brachycarfon as varieties, recognizes Phascum rostellatum Brid. as a Hymenostomum, designates it however as H. microstomum var. /. inutilatum Heuben. In Bry. Eur., 1846, Gymnostomum tortile Schwaegr. is after Fuernroh's example described as a Hymenostomum, however H. rutiians (Hedw.) is made a synonym of W[eisia mucronulata Bruch., and H. subglobosum Bryol. Germ. a synonym of UZeisia viridula; further H. rostellatum is treated as an Astomum, and by error H. crisfpatum Bryol. Germ. is also removed. C. Mueller in his Synopsis (I849) treated Hymenosfomum as a subgenus of Weisia; so also Juratzka (1882). Schimper in I86o puts it as a subgenus under Gymnostomum, yet G. rostellatum is counted in; in the second edition of the Synopsis (1876) it is again raised to the rank of a genus and H. unguiculatum Phil. is added: by gross error H. crisiatum Bryol. Germ. and H. murale (Spruce) are placed here. In Milde, who followed Lindberg, the genus is withdrawn in 1869, and its species are thrown in the subgenus Euweisia C. Muell, emend. Lindberg, in I879. considered Hymenostomuzu, including Euweisia C. Muell. and Astormum (Systegium) as a subgenus of ,Mollia Schrank emend., a genus which in respect to structure of capsule and the anatomy of its stem and of leaf costa comprises in its limits diverse elements. Since according to present views a valid taxonomic arrangement cannot be founded on the structure of vegetative organs merely, Hymenostomum is entitled to generic rank, for here in the so-called hymenium of the spore case we find a structure which has its analogue only in the drumhead, (the epiphragm or diaphragm) of the Polytrichacele. Strictly speaking H. microstomum and H. squarrosum are the only representatives within our territory, for H. rostellatum may be viewed as an Astomum and H. tortile probably does not belong here at all. That H unguiculatum Phil. represents a Trichostomum mutabile with rudimentary peristome is known; yet Hymenostomum MAuelleri Bruch from Corsica (Flora, 1829, t. 2
Read full abstract
Jan 1, 2022
M.M Makhmudova 
Open Access
