MOSSES Willi A HAND-LENS 19 



branches. The capsules are almost spherical, with a clear-cut 

 lid and no peristome; they mature in spring. 



An attempt has been made to illustrate the remarkable trans- 

 formation that these plants undergo when moistened, but no 

 drawing can do justice to the magic of the change. 



Our only species is H. dlbicans (Web.) Lindb. {H. ciliata 

 Ehrh.) 



WEISSIA 



THE Weissias have the characteristic brownish-green or black- 

 ish-green color of the Grimmia family. They are distin- 

 guished from all save Orthotrichum by the hairy calyptra. 



Both Orthotrichum and Weissia grow on the bark of trees or 

 more rarely on rocks, in cushions of varying size and thickness. 

 The Weissias growing on trees usually grow in more rounded tufts 

 with the leaves more crisped when dry than is usual with Orthot- 

 richum growing in similar situations. The books all say that the 

 hairs on the calyptra of Weissia are flexuous, and those on Orthot- 

 richum straight, but this distinction appears to be rather too line 

 for the amateur to profit by it. The capsules in both genera are 

 erect and symmetric and quite regularly striate when dry with 

 eight or sixteen ridges and as many alternating furrows. These 

 ridges consist of cells larger, darker, and thicker- walled than the 

 alternating tissue. The seta in Orthotrichum is so short that the 

 capsule is nearly always partially immersed; in Weissia the seta 

 is long enough to exsert the capsule entirely beyond the perichse- 

 tial leaves. 



Orthotrichum is a very large and difficult genus, and cannot 

 be successfully treated in a book of this kind. Weissia is a small 

 genus whose species are easily recognizable without any lens 

 whatever. 



The Puckered Weissia has pear-shaped capsules, abruptly 

 narrowed to the very small mouth ; the ridges and furrows extend 

 only a short distance around the mouth of the capsule, giving it 

 the peculiar and characteristic appearance shown in the cut. 



The capsules of the Crisped Weissia have a much larger mouth 

 and are striate for the entire length. The seta is shorter, the color 

 is lighter, and the tufts are rather thicker than in the Puckered 

 Weissia. In a not uncommon variety of the Crisped Weissia the 

 capsule is much shorter and is suddenly contracted into a neck. 



