MOSSES WITH A HAND-LENS 8l 



All three of the Ulotas are common in the hilly regions of 

 our range. Their capsules mature in autumn or early 

 winter, but apart from the calyptra are more characteristic when 

 dry and empty. The tree-growing species furnish good collect- 

 ing for winter and early spring, when most other mosses are 

 buried under the snow. 



The use of the name Ulota instead of Weissia seems to be 

 sanctioned by the best authorities, hence the change. 



ORTHOTRICHUM. 



The Orthotrichums are most frequent on trees about houses, 

 and in orchards and village streets, although they are not lacking 

 in other situations where the trees stand somewhat apart. They 

 can be found abundantly on almost any fruit or shade tree in 

 the country. In the larger cities for some reason they do not 

 seem to thrive. They may frequently be found growing with 

 Ulotas, from which the immersed or emergent capsule and non- 

 crisped leaves distinguish them at once. One species (O. 

 anomalum) grows on rocks. The calyptras are less densely 

 hairy than those of Ulota ; O. strangulatum has a calyptra without 

 hairs. The species are usually considered difficult to identify 

 even with a compound microscope, but I find that a few of the 

 commoner species can be recognized with the aid of a hand-lens. 

 Capsules must be thoroughly dry to answer the description of 

 dry capsules. The leaves have revolute margins, except in 



0. obtusifolium, which appear as a darker margin when the 

 leaves are mounted on a slide. Drummondia has the general 

 appearance of an Orthotrichum with an exserted capsule, but the 

 calyptra is cucullate and without hairs and the capsule is not 

 wrinkled when dry. 



The plate of O. sordidum gives a good idea of the character- 

 istics of the genus. 



KEY. 



1. Rock-inhabiting species; peristome teeth 16, erect or erect-spread- 



ing on dry capsules; capsule fully exserted, i6-striate. . . .anomalum. 

 Tree-inhabiting species; peristome teeth usually united into 8 

 pairs, recurved or reflexed when dry; capsule immersed or 

 emergent, 8-striate 2. 



2. Leaves obtuse (rarely with some leaves acute), broad pointed, 



margins plane obtusifolium. 



Leaves acute, margins revolute or involute 3. 



3. Capsule almost or quite exserted, smooth, or very slightly 



plicate around the mouth when dry and empty speciosum. 



