— 93 — 



QQ, Usually at least some of the leaves of the branch-tips with hyaline 

 points, but sometimes all muticous; seta 10-14 rnm. long; capsule- 

 body 3.3-3.8 mm, long; peristome-teeth 1.5-1.7 mm. long; leaf- 

 surface depressed over the cell-cavities. 9. R. varium 



QQQ. None of the leaves with hyaline points; seta 4-12 mm. long; cap- 

 sule-body 2-2.5 mm. long; peristome-teeth about .6 mm. long; leaf- 

 surface depressed over the cell cavities. 14. R. fascicular e 

 PP. Vein extending only to about the middle of the leaf. 13. R. palmeri 



Analytic Statements 



Only R. palmeri has the vein ending much below the tip. 

 Only R. vartum has the capsule-body reaching 3 mm. long. 

 Only R. cyclodictyon is red or reddish-brown. 



Only R. aciculare has teeth on the margin other than on the hyaline point, 

 and it does not always have them. 



Only R. lanuginosum has the seta rough. 



Only R. patens, R. sudeticum, R. affine and R. macounii have the margin 

 more than i cell thick toward the apex. 



Only R. canescens and R. varium have the peristome-teeth i mm. or more 

 long. 



Only R. sudeticum occidentale has teeth on the surface of the hyaline point. 



Only R. canescens has distinct papillae on both surfaces of the leaves; but 

 R. lanuginosum has a few near the hyaline point. 



Only R. canescens and R. lanuginosum have papillae on the hyaline point. 



Only R. patens, R. canescens and R. lanuginosum have the seta twisted 

 to the left.* 



I. Rhacomitrium patens (Dicks.) Hueb. Muscol. Germ. p. 198, 1833. 

 [Dryptodon patens Brid.; Grimmia patens B. S. G.] 



Plants in loose mats, green to brownish or blackish; stems up to 12 cm. 

 long, with few elongated branches and none to few short tuft-like lateral branches; 

 central strand none. Leaves about 3 mm. long, lanceolate, gradually narrowed, 

 keeled above; when dry appressed, slightly crispate; when wet strongly squarrose; 

 tip usually muticous, often with a few teeth; margins 2 cells thick toward tip, 

 revolute at base; vein about .12 mm. wide near base, with 2-4 longitudinal lamel- 

 lae on under side; lamellae 1-2 cells thick, 2-5 cells high. Cells strongly convex 

 on surface of leaf, round-quadratic from tip of leaf to below middle and 8-9ju 

 in diameter, greatly elongated from near middle to base; basal cells linear; alar 

 cells rectangular to quadrate. Dioicous. Calyptra mitrate, sometimes almost 

 cucullate. Seta 3-5 mm. long, twisted to the left, curved, yellowish. Capsule 

 horizontal, eventually almost erect, oval, smooth, becoming somewhat grooved 

 in old age, its body 1.6-1.8 mm. long. Lid about ^ the length of the capsule 



* Conceive a clock with face turned up. Conceive a moss-plant upright on the face of the 

 clock. If the capsule is twisted in the direction in which the hands of the clock move, the seta is 

 said to be twisted to the right; if in the opposite direction, to the left. 



