452 HYPNACE^. 



/Leaves single-nerved ^ 



\ Nerve absent, or short and double 5 



/Ls. narrowed above to a long, very narrow acumen ; plant slender 3 



\Ls. more gradually tapering to a wider acumen ; plant larger 4. 



/Nerve running up far into the acumen 2. elodt? 



3\Nerve ceasing about half-way up leaf 4* chrysophyllum 



/Ls. distinctly auricled with enlarged cells at angles .3. polygamum 



^\Basal cells enlarged, but not forming distinct auricles 1. riparium 



/Ls. sharply serrulate, all strongly recurved 6. Halleri 



->\Ls. almost entire above, less recurved 6 



, / Stem creeping, slender ; angular cells of ls. small, quadrate .5. Sommerfeltii 



b \S 



^ Stem usually erect ; angular cells dilated 4. stellatum 



1. Hypnum riparium L. (Amblystegium riparium B. & S., 

 Schp. Syn. et mult, auct.) (Tab. LVI. H.). 



Very variable in size and habit ; typically low, creeping, sub- 

 pinnate with short, spreading branches ; bright or yellowish 

 green, 2-3 inches long ; leaves long, 1-2 lines (occasionally 

 smaller) widely spreading or almost squarrose both wet and dry, 

 often sub-complanate, rarely erecto-patent, but often forming a 

 cuspidate tuft and secund at the tips of the branches; silky; 

 more or less widely ovate-lanceolate or oblong-lanceolate, longly 

 and gradually finely acuminate, rounded at base to a narrow, 

 shortly decurrent insertion. Margin plane, entire; nerve strong 

 at base, reaching above the middle and usually ^ the length of the 

 leaf ; cells linear-rhomboid, acute, 10-15 times as long as broad, 

 thin-walled, chlorophyllose ; becoming lax at some distance above 

 the base, gradually towards angles larger, rectangular and often- 

 pellucid, but not forming distinct nor hyaline auricles. Seta 

 ^-1 inch long ; capsule oblong-cylindric, somewhat turgid, 

 strongly curved ; peristome large. Autoicous. 



Var. f3. longifolium Schp. Leaves narrow, lanceolate- 

 acuminate, with a very long and tapering, almost filiform acumen ; 

 rather distant. Stems with almost simple, hardly branched 

 divisions, usually sub-complanate . 



Var. y. splendens De Not. Resembling var. longifolium in 

 habit but with very large, broad leaves, less finely acuminate, 

 more crowded, very regularly imbricated, less complanate. 



Hab. Roots of trees, stones, etc. , near water. Common. The vars. /3 and y 

 floating, in pools, etc. , less common. 



A very variable plant, but usually known by the longly-pointed, entire leaves, 

 widely divergent and straight when dry, with a long stout nerve and linear, pointed 

 areolation ; in the latter character it is typically very different from all the species of 

 Amblystegium, with which it is usually united ; while the single-nerved, entire, not 

 plicate leaves will at once distinguish it from any of the species of the previously 



