440 hypnace^e. 



Hab. Wet, shady rocks, very rare ; S.W. Ireland ; N. Wales. Fr. autumn. 



This very rare and distinct plant is only found, in Britain, in four or five localities 

 in the districts above-mentioned. It is very distinct in habit, mode of growth and 

 areolation, the very few, but very distinct angular cells, inflated, thin-walled and 

 hyaline, being very different to those of any of the allied species, though similar to a 

 group of (chiefly American) species, Hypnum recurvans Schwgr. , and others, separated 

 by Lesquereux and James under the genus (or sub-genus) Raphidostegium (Raphido- 

 rrhynchum Schp. ), and perhaps well deserving of a separate rank. Plagiothecium 

 striatellum, however, shows a somewhat similar structure. P. demissum grows on the 

 inclined faces of rocks in very wet situations, often turning a bright golden brown ; 

 it is usually closely attached to the surface of the rock. The fruit, which is rather 

 small for the size of the plant, is somewhat copiously produced all along the stems. 



1 14. AMBLYSTEGIUM B. & S. 



Plants of differing habit and branching, rarely pinnate ; 

 usually preferring moist situations. Leaves usually small, mostly 

 more or less ovate-acuminate , usually imbricated all round the 

 stem, not complanate nor strongly falcate, though frequently 

 moderately falcato-secund ; nerve single or rarely none. Cells 

 more or less parenchymatous , short, often less than j times as 

 long as wide, usually rhomboid-hexagonal. Seta smooth ; capsule 

 narrow, more or less cylindrical, usually curved ; lid conical, 

 obtuse or apiculate, rarely more longly acuminate. 



An ill-defined genus, founded by Bruch & Schimper principally 

 on the mode of branching (not pinnate as frequently in Hypnum), 

 the areolation, and the short, not rostrate lid. I have followed 

 De Notaris and Husnot in placing here Hypnum filicinum and 

 the allied species with similar areolation ; in spite of its resemb- 

 lance to H . commutatum the areolation must be held of more 

 importance, and H . filicinum is clearly in an anomalous position, 

 from this point of view, when placed in that connection. Its 

 affinity to A. irriguum, etc., is also obvious, and I think nothing 

 is lost by making this change ; while the present genus is rendered 

 a fairly natural one, based principally on this character of the 

 cell structure, by so doing and by removing A. riparium to 

 Hypnum. This latter species is clearly in an anomalous position 

 in the present genus, the areolation being totally distinct, and 

 much more like that of Hypnum aduncum, which some of its 

 forms closely resemble, but to which it can hardly be considered 

 nearly allied ; it appears to be more at home in the Section 

 Campylium of Hypnum, in which place it will be found in the 

 present work. 



The distinguishing characters of this genus, as regards our 

 British species, will, if kept in mind, make it easy to recognise 



