466 HYPNACE/E. 



Hab. Bogs, rare ; usually barren. 



H. vernicosum, H. revolvens var. Cossoni and H. intermedium are very closely 

 allied plants, and the distinction between them is possibly not so great as the 

 preceding arrangement would indicate, depending chiefly, as regards H. vemicosum, 

 on the plication of the leaves. 



14. Hypnum commutatum Hedw. (Amblystegium glaucum 

 Lindb.) (Tab. LVII. J.). 



Typically slender, the stems more or less erect or ascending, 

 divided, regularly and complanately pinnate and plumose, 3-6 

 inches long, bright green, orange internally, frequently encrusted 

 with calcareous matter. Very variable in size, branching, and 

 colour. Stems more or less densely tomentose with brown 

 radicles, and with numerous lanceolate or linear-subulate para- 

 phyllia. Leaves rather small, about 1 line long, usually more or 

 less strongly falcate or circinate, but often pointing in various 

 directions or more or less irregularly spreading, branch-leaves 

 rather narrower, more regularly falcato-secund and homomallous ; 

 stem-leaves widely cordate-triangular from a broad decurrent 

 base, rapidly narrowed to a long, channelled, tapering acumen, 

 which is very flexuose and more or less crisped when dry ; deeply 

 plicate, strongly denticulate at basal margin, more indistinctly 

 above ; nerve green, very thick and strong, especially at base, 

 reaching about half-way up the acumen ; cells short but narrow, 

 50-80 /i long, 8-10 times as long as wide, tapering, but not very- 

 acute, linear ; at base lax, sub-hexagonal, pellucid, especially at 

 margin ; below these at angles suddenly large, hyaline, inflated, 

 forming large decurrent auricles. Perichaetial bracts plicate. 

 Seta long, if -2 inches ; capsule large, cylindric, arcuate, bright 

 orange-brown, annulate. Dioicous. 



Hab. Bogs and streams, most abundant in calcareous soil. Common. Fr. 

 early summer. 



Another very protean species, in its slender forms resembling Amblystegium 

 filicinum, but more densely and regularly pinnate, with wider, softer, plicate leaves 

 more flexuose when dry, and especially with longer, narrower, linear, not hexagonal 

 areolation. It varies much in colour, but most of all in degree of robustness, size of 

 leaves and mode of branching, and some forms can hardly be separated from the sub- 

 species H. falcatum. It cannot easily, however, be taken for any other species if due 

 attention be paid to the wide leaf base, plicate leaves with large decurrent auricles, 

 and to the presence, often in great abundance, of radicular tomentum and of 

 paraphyllia. Although dioicous it is more frequently found in fruit than many of the 

 allied species. 



Thuidium decipiens is extremely like H. commutatum, and is often placed here 

 in bryological works (H. Notarisii Boul. ) ; for the differences between the two, see the 

 description of that species. 



