PLAGIOTHECIUM. 437 



* Plagiothecium sylvaticum B. & S. (Hypnum sylvaticum L.) 



(Tab. LV. I.). 



Closely allied to P denticulatum, and sometimes hardly or 

 not separable from the var. majus of that plant except by the 

 dioicous inflorescence and the always smooth capsule. It is 

 usually, however, very different in habit from ordinary P. 

 denticulatum, and will as a rule be easily identified from the 

 following- description. Tufts large, dull deep olive green, usually 

 with a lurid yellowish tinge ; more robust than P. denticulatum, 

 the leaves larger, less regularly complanate, but not hooked nor 

 sub-secund, widely spreading, when dry much shrinking and 

 somewhat twisted, so as not to overlap one another and thus 

 appearing distant, not or scarcely glossy, i-i£ lines long, widely 

 ovate-lanceolate, more narrowed at the base and more tapering 

 above, acute, entire or obsoletely denticulate at apex, margin 

 plane, nerve usually very faint ; cells large, wide, hexagonal- 

 rhomboid, 8-10 times as long as wide, 100-160 /x long, about 16 /u 

 in diameter. Seta long, capsule large, \\ lines long, cylindrical 

 with a tapering neck, inclined, slightly curved, smooth, not 

 striate ; lid conical with a more or less elongated beak, sometimes 

 distinctly rostrate. Dioicous; male flowers numerous on the 

 lower half of the branches. 



Var. fi. Sullivantix Spr. (Plag.Sullivantise Schp.). Leaves 

 glossy when dry, less distinctly complanate ; nerve long and 

 rather strong, cells narrower, lid shorter. 



Var. y. succulentum Wils. Robust ; leaves large ; fertile 

 flowers large, tumid, occasionally synoicous. 



Hab. Peaty soil, rocks, etc., in woods. Common. The var. j3, Kirkstone 

 Pass (Stabler) ; the var. y very rare ; Cheshire ; Yorkshire ; N. Wales. Fr. 

 rather rare, summer. 



The above description will render it as a rule fairly easy to distinguish the 

 present plant from P. denticulatum, especial attention being paid to the general 

 colour and dullness of the tufts, the leaves much shrinking and scarcely glossy when 

 dry, the plane margins and lax cells, the smooth capsule, long lid, and dioicous 

 inflorescence. When a difficulty arises it is not, as a rule, owing to this plant 

 approaching P. denticulatum ; for although a somewhat variable moss, the varieties 

 of P. sylvaticum depend as a rule on structural details rather than on difference of 

 habit, and its general facies is a fairly constant one. But P. denticulatum is 

 extremely multiform in habit as well as other points, and in the var. majus especially 

 it approaches so near P. sylvaticum that one is finally obliged to admit that there is 

 nothing but the difference of inflorescence, and perhaps the striation or otherwise of 

 the capsule, to separate the two. The leaves in that variety are often shrunken when 

 dry exactly as in P. sylvaticum, with a varying, often slight degree of glossiness, the 

 cells large, fully as wide as in this plant, the margin often plane, the capsule long and 

 narrow, the lid decidedly rostrate ; it thus recedes far from typical P. denticulatum, 

 which is at once recognised by its pale shining leaves, hardly altered when dry, and 



