THE POLYTRICHACEZ OF WESTERN NORTH AMERICA 273 
5. Peristome wanting. 
6. Stomates present on capsule. es 
Tew AP SUeMenebe! me tei cic, tar WAS cn Sats Bartramiopsis. 
5. Peristome present. 
-6.. Stomates present on capsule. 
Wee Capsule benelernte iar c el tial Dendroligotrichum. 
2. Lamalle on upper side 20 or more. 
3. Lamina of 1 layer of cells. 
4. Leaves not bordered. 
5. Peristome wanting. 
6. Stomates present on capsule. 
qj. WCenosulls aati guleee soe 5 oc cee - Polytrichadelphus. 
3. Lamina of 2 layers of cells. 
4. Leavesnot bordered. 
5. Peristome wanting. 
6. Stomates present on capsule. . 
7. Capsule keeled on one side, somewhat oval in cross 
SOCHOM ose ie ol pen ieee Eee m nha ars ar ial Lyellia. 
1. Calyptra densely covered with hairs. 
2. Lamelle wanting. 
3. Lamina of 1 layer of cells. 
4. Leaves not bordered. 
5. Peristome present. 
6. Stomates wanting on capsule. 
Fa OC amsuile Heretey). acca e wie Wei eis a Racelopus, 
2. Lamelle on upper side 20 or more. 
3. Lamina of 1 layer of cells. 
4. Leaves not bordered. 
5. Peristome present. 
6. Stomates either present or wanting on the capsule. 
FeO asus LPETEb emer strc ttt tis ens ake Pogonatum. 
6. Stomates present on capsule. 
ae apsule. 4;-On AMCled ay ia ay cee Polytrichum. 
1The writer has followed the classification of Brotherus in Engler & Prantl: “Die 
natiirlichen Pflanzenfamilien,” Teil 1, Abt. 3, s. 669-698 (1904) except in the separa- 
tion of Pogonatum from Polytrichum. The chief question here arising is where to 
put Pogonatum alpinum. Excepting this plant the Pogonatums have capsules terete, 
teeth 32, stomates wanting; the Polytrichums have capsules angular, teeth 64, stomates 
present; Pogonaitum alpinum is a fine gradation form between the two genera, having 
the terete capsule of the Pogonatums, the stomates of the Polytrichums, and standing 
between the two genera in its 32 or 64 teeth depending upon how one counts the doub- 
ling. Whether one classes it a Pogonatum or a Polytrichum depends upon whether one 
emphasizes the form of the capsule or the presence of the stomates. When there is 
nothing to be gained by using a microscopic character in the separation of genera, 
why not use one which can be seen with the naked eye? In this paper Pogonatum 
alpinum is therefore classed as a Pogonatum. 
