— 9 — 
The longer plants are the most yellowish, but there is a gradual gradation. 
Some plants have many tuft-like lateral branches but most of them have several. 
Most plants have hyaline points on the leaves at the branch-tips, but some have 
all of the leaves muticous. The striking characteristic is the long capsule. The 
variability of the species has been the cause of considerable confusion in our 
western Rhacomitriums. The cells of the marginal row near the leaf-tip are 
isodiametric, so are also often a few cells in the tips of the muticous leaves; but 
otherwise opaque cells of the leaf-tips are nearly all 2 or more times as long as 
wide. This has been confusing in keys based on leaf-cells. C. Mueller was in 
error in reporting the annulus lacking. 
10. Rhacomitrium canescens (Weis) Brid. Mant. p. 78. 1819. 
Plant yellowish-green or grayish-green. Stems up to 10 cm. long; elong- 
ated branches none to few, short tuft-like lateral branches none to rather numer- 
ous. Leaves lanceolate, papillose on both sides, usually most of them with 
hyaline points; hyaline point papillose, dentate, up to half the length of the leaf; 
papillae not paired, over the cell-cavity; margin 1 cell thick throughout. Green 
cells of the leaf-tip 1-2 times as long as wide, of the leaf-middle scarcely longer, 
of the leaf-base 4-6 times as long as wide. Dioicous. Calyptra very warty. 
Seta 7-25 mm. long, smooth, twisted to the left. Capsule elliptic, about 2 mm. 
long; lid as long as or longer than the body of the capsule. Peristome-teeth 
1. 3-1. 6 mm. long, finely papillose, split to the base. Spores 8-10/x. 
10a. Rhacomitrium canescens ericoides (Web.) B. S. G. Bryol. Eur., Fasc. 
25-28, 1845. [R. ericoides Brid.] 
1. Most of the leaves with hyaline points. 
2. Plants yellowish green. 
3. Short tuft-like lateral branches very numerous. — Alaska to Oregon 
and Montana. 
Typical. 
1. Most of the leaves with hyaline points. 
2. Plants green, not greatly yellow. 
3. Short tuft-like lateral branches not very numerous. — Alaska and 
Yukon to California and Montana. 
10b. Rhacomitrium canescens epilosum Milde, Bryol. Siles. p. 160. 1869. 
[R. canescens muticum Vent.; R. canescens muticum Kindb.] 
1. None of the leaves with hyaline points, or a few with very short ones. 
2. Plants green, not greatly yellow. 
3. Short tuft-like lateral branches not very numerous. — Alaska to Wash- 
ington. 
Macoun’s descriptions of Rhacomitrium canescens muticum do not agree. 
In Bull. Torr. Bot. Club 17: 272, 1890, the costa is said to be wanting; in Cat. 
Canadian PI. 6: 77, 1892, the costa is said to be excurrent. Examination shows 
it to be excurrent in the longest leaves, and not reaching the apex in the shorter 
ones. There is nothing in the description to separate it from R. canescens epi- 
losum Milde; and while material of R. canescens epilosum has not been accessible, 
it is very likely that it is the same as Kindberg’s var. muticum. 
