BRACHYTHECIUM. 399 



/Autoicous or rarely synoicous ; Is. often serrulate above 6 



- > \Dioicous; Is. nearly or quite entire 7 



, / Seta smooth throughout 4. salebrostim 



\ Seta smooth below, rough above j. campestre 



/Branches few, erect, cylindric ; Is. pale 3. albicans 



' \Stem usually procumbent, more branched ; acumen twisted 2. glareosum 



0/ Seta rough above, smooth below; Is. often secund 13. plumosum 



\ Seta rough throughout 9 



I Stem-leaves with cordate base and decurrent wings and long fine points (alpine 



9-! plants) 10 



^Stem-leaves not cordate, rarely decurrent 11 



/Plant small and slender ; nerve reaching far into acumen 10. reflexum 



\ Plant larger ; nerve ceasing far below acumen 8. Starkei 



/Ls. nerved nearly to apex, narrow, with very narrow acumen 12. populeum 



\ Nerve ceasing some distance below apex 12 



/Ls. with distinct auricles of hyaline cells 13 



\ Auricles absent, or indistinct and greenish 14 



/Dioicous ; ls. usually large and wide ; plant robust 7. rivulare 



■^\Autoicous ; plant small ; ls. more or less imbricate <?. glacials 



/Plant robust ; ls. widely ovate, over 1 line long 6. rutabulum 



^\Plant slender ; Is under f-line long 15 



/Ls. more or less imbricate ; branches few and slender 14. cczspitosum 



^\Ls. divergent, often sub-secund ; branches numerous and short ...it. ■velutinum 



1. Brachythecium plicatum B. & S. (Hypnum plicatum 



Schleich. ; Ptychodium plicatum Schp., Syn. ; Lesquereuxia 



plicata Lindb.) (Tab. LII. F.). 



Robust, dull yellowish green or brownish. Stems creeping, 

 divided, 2-5 inches long, rather rigid ; divisions prostrate, 

 somewhat pinnately branched, the branches stout, not attenuated, 

 sub-terete when dry, erect or ascending. Leaves closely imbri- 

 cated, erecto-patent or slightly sub-secund, large, about 1 line 

 long, rapidly and longly acuminate from a wide, ovate base, 

 deeply plicate, interspersed with numerous, multiform para- 

 phyllia ; margin entire, widely revolute; nerve strong, reaching 

 into the acumen. Cells narrowly linear-rhomboid, somewhat 

 vermicular, 8-15 times as long as broad, towards base slightly 

 shorter and wider, at extreme base short, incrassate, with the 

 walls porose ; at angles rather large, sub-quadrate , opaque, 

 numerous. Seta smooth. Capsule horizontal or inclined, oblong, 

 arcuate ; lid acutely conical. Inner peristome without cilia. 

 Dioicous. 



Hab. Alpine calcareous rocks. Very rare ; the Ben Lawers range of mountains. 

 Fruit very rare, autumn. 



There is little difficulty in identifying this moss, as tKe allied species with strongly 

 plicate leaves are all found in different habitats ; the leaves also are wider and more 

 suddenly acuminate, and the plicae more irregular, than in Camptothecium or Pleuropus, 

 and the paraphyllia, the long nerve, and the narrow, elongated cells separate it from 



