ORTHOTRICHUM. 259 



F. OBTUSIFOLIA. 



17. Orthotrichum obtusifolium Schrad. (.Tab. XXXVI. C). 



In small dense tufts, dull yellowish green, stems turgid, with 

 a very few short thick branches, hardly 1 inch high. Leaves 

 erecto-patent, when dry closely imbricated, short and very broad, 

 oval-oblong, very narrow at the insertion, concave, broad and 

 rounded at summit, margin erect, not recurved nor involute, with 

 projecting papillae, which at the apex almost amount to denticula- 

 tions ; basal cells rectangular, upper hexagonal or elliptic, large, 

 about 15 fi, incrassate, each with a stout projecting often bifid 

 papilla. Short brown or green clavate jointed gemmse are usually 

 found on the surface of the leaf. Capsule immersed, oval-oblong 

 with a tapering neck, with 8 faint ribs; stomata superficial; 

 calyptra naked, brownish ; peristome double, yellowish. Dioicous. 



Hab. Trees, rare and barren. 



This very distinct species is readily known by its broad, rounded leaves, which 

 give a tumid appearance to the stems ; in its erect leaf-margins too it is quite different 

 from the other species of the genus so far as our British plants are concerned. There 

 is however a continental and N. American species, 0. gymnostomum Bruch, which in 

 the leaf form closely resembles it, but has involute margins, and' no peristome. A 

 specimen of this species labelled " England, Yorkshire," is said by Braithwaite to have 

 been sent to Venturi by Jaeger. 



Although the leaves in the present plant, are normally and indeed almost con- 

 stantly obtuse, yet they may occasionally be found more acute ; I have found them 

 very obtusely pointed in plants of my own collecting, and Mrs. Britton mentions 

 plants from Jordansville, N.Y., with the leaves acute or even apiculate, and the 

 perichoetial bracts acuminate, on stems bearing also the ordinary rounded, obtuse 

 leaves. It is possible that owing to its small size and the absence of fruit this species 

 may have been overlooked and may be really more common than has been thought ; I 

 have found it in several localities in Northamptonshire, principally on ash, but also 

 on willows. 



Order XII. SCHISTOSTEGACE^E. 



Plants small, slender. Stems of two forms, barren, with the 

 leaves distichous, having their bases confluent; and fertile, with 

 similar but smaller leaves or with a terminal tuft or rosette of 

 small leaves. Areolation lax ; nerve none. Capsule minute, sub- 

 globose, gymnostomous ; lid plano-convex ; calyptra small, conical. 



A very distinct Order, consisting of a single genus, and 

 represented by one species only, having little affinity with any 

 other moss. 



