DicRANACE^.] 140 [Dicranuni. 



Readily distinguished from the last by its longer acute leaves, distinct 

 perichaetium and shorter capsule, and it is also confined to the more elevated 

 mountains. When growing exposed to the constant drip of snow water it 

 assumes a black colour and the leaves and capsules are shorter, it then 

 becomes the var. atrata Nees Hsch. and connects itself to D. compacta 

 (ScHLEiCH.), which has been recorded from Ben Lawers, but the specimen 

 we have received is not the plant ; D. compacta also is properly regarded by 

 Lindberg as a var. of 13. crispula. 



DICRANUM HEDVi^. 



Fund. muse. II, 91 (1782). 



Plants usually tall and handsome, dichotomous, rooting only at 

 base, or the whole stem covered with radicular tomentum. Leaves 

 patent or falcato-secund, smooth or rarely papillose, glossy or opake, 

 long and lanceolate or lanceolate-subulate ; nerve semiterete or more or 

 less dilated ; areolation narrow and elongated rectangular in the lower 

 part, with the angular cells quadrate dilated vesicular and colored 

 orange or brown, above lineal-oblong quadrate or elliptic, often 

 flexuose ; perich. bracts sheathing. Caps, erect or cernuous, rarely 

 striate, with a short equal neck, rarely strumose, generally annulate ; 

 lid rostrate ; teeth 16, orange or deep red, confluent at base, cleft half 

 way or more into 2 — rarely 3 — unequal subulate legs, striolate at 

 base, trabeculate internally ; calyptra cucullate, rostrate, usually falling 

 with the lid. Male infl. gemmaceous. Inhabiting the ground, rocks or 

 rarely trunks of trees. Deriv. — hiKpavov a fork. 



This very natural genus comprises about 100 species, varying 

 considerably in size ; and also in general aspect. As originally established 

 by Hedwig, when the peristome was regarded as affording almost the sole 

 essential character, it included a miscellaneous collection — Ceratodon purp., 

 Leticohryiim, Grimmia acicnlaris, Dicvanella heteromalla, Dichodontitim pellucidum 

 and Dicraimm scoparhim — the last being retained as the type of the genus. 

 In the highest developed forms D. imdulatuni, Bonjeani, scoparium, &c. 

 constituting Lindberg's section Eudicranum, the longitudinal walls of the 

 leaf-cells will be seen, by proper amplification, to be perforated by fine pores, 

 by means of which the cells communicate ; these are wanting in the other 

 sections, and in the few species which have papillose leaves as D. montanum, 

 the papillae are simple conical elevations of the cell-cuticle ; the vesicular 

 colored angular cells are the most characteristic feature in this genus. 



On the felted mass of radicles which clothes the stem of several species, 

 small tubercles form which develope into male gemmae, and in D. scopayium 

 grow on into independent male plants. 



The other European species are D. hyperboreum, Anderssonii, elatum, 

 undulatum, fragilifoUtim, strictum, Miiehlenbeckii, hrevifolimn, fulvtmi, albicans and 

 comptum ; of these D. undulatum is a species which ought to occur here, being 

 found in alpine woods throughout Europe and N. America, but although it 

 has been several times reported from various localities, no genuine specimen 



