DICRANUM. 113 



D. fragilifolium Lindb. , another very brittle-leaved plant, is nearer D. fuscescens 

 and D. elongatum, with the lower cell-walls distinctly porose ; it is found in 

 Scandinavia and N. America. 



N.B. — In the plate representing this species (Tab. XIX. A.) one or two slight 

 errors have crept in ; the single denticulation in the magnified apex of the leaf (id) 

 has become enlarged in the process of lithographing and is a little too strongly shown. 

 The plate also shows the areolation near the base of D. viride (for vitide read viride), 

 as well as that of D. strictum, for purposes of comparison. 



16. Dicranum flagellars Hedw. (Tab. XIX. B.). 



In close tufts, 1-2 inches high, bright or yellowish green, 

 radiculose, frequently emitting numerous axillary, erect, straight 

 flagellx with minute leaves. Leaves curved, subsecund, crisped 

 when dry, from an oblong base gradually narrowed to a linear- 

 subulate tubular acumen, slightly denticulate at and near the apex ; 

 nerve narrow but variable, usually -i— \ width of base, not excur- 

 rent, slightly denticulate at back near apex ; angular cells wide, 

 quadrate, yellowish brown, reaching to or almost to the nerve ; 

 above rather loosely rectangular, becoming shortly rectangular in 

 the limb, towards the summit quadrate or nearly so, irregular, 

 angular, smooth at back. Capsule elongate, cylindric, symmetrical 

 or faintly curved, striate when dry, lid subulate, oblique. 



Hab. Rotten tree trunks, very rare. Sterile in Britain. 



On the Continent this is a not unfrequent species, and its rarity here is therefore 

 somewhat remarkable. The flagelliform ramuli are not always present. It is then 

 much like D. montanum, but that species forms neater rounded cushions usually (in 

 this country at least) on living trees, and has the leaves papillose at back, more 

 denticulate above and more closely and strongly crisped when dry. From D. strictum 

 it differs in the hardly fragile, denticulate leaves, the latter character also separating 

 it from D. Scottianum, which also has much smaller, more rounded areolation. 



17. Dicranum montanum Hedw. (Tab. XIX. C). 



In small dense rounded cushions, bright or dark green, 

 hardly 1 inch high. Leaves spreading or subsecund, strongly 

 crisped when dry, rather shorter and smaller than in the last 

 species, from a lanceolate base gradually narrow-linear, less 

 acutely subulate, slightly tubular above, distinctly denticulate 

 towards apex at margin and on the back of the nerve which is 

 narrow, about \ width of base, not excurrent ; cells at angles 

 not much enlarged, hyaline or brown, the other basal cells 

 narrowly hexagonal-rectangular, thin-walled, above shorter, in 

 the upper part sub-quadrate, strongly papillose. Capsule oblong- 

 cylindric, erect or slightly curved, finally plicate. 



Hab. Roots and trunks of trees in woods, etc. ; rare. Sterile in Britain. 



I 



