24 DICRANACEAE 



not apiculate; Phascum cuspidatum with a round smooth ex- 

 current costa and upper leaf cells rounded hexagonal and papil- 

 lose on the back; some other small species of the Tortulaceae 

 which also have papillose cell walls, or have ovate or ovoid 

 leaves with costa vanishing or slightly percurrent; Ephemerum, 

 in which the plants are stemless, being scarcely more than buds 

 on a persistent protonema. 



Key (adapted from N. Am. Flora) 



I — Calyptra mitrate; stomata of the capsule wall median palustre 



Calyptra cucullate; stomata of the capsule wall basal 2 



2 — Leaves erect-appressed, imbricate, ovate or mucronate Sullivantii 



Leaves spreading or secund, lanceolate-subulate 3 



3 — Antheridial buds usually axillary to the lower leaves; perichaetial 

 leaves abruptly subulate, the awn long and roughly serrate. 



alternifolium 

 Antheridia in the perichaetium; perichaetial leaves tapering into 



the awn 4 



4 — Perichaetial leaves entire at base, awn rough subulahim 



Perichaetial leaves toothed at base, awn nearly smooth Ravenelii 



P. subulatum (L.) Rabenh. Frequent on sandy banks and 

 in old fields. April-June. 



P. alternifolium (Kaulf.) Rabenh. New Dorp, S. Id., E. G. B., 

 Bx!; Staten Id.!!; "Old fields, Closter, N. J.," Austin, Bx!; 

 "Glen Cove, L. Id., Sanial," Flora, L. Id. May-June. 



P. Ravenelii Aust. "On light sandy soil. New Jersey," Muse. 

 App. Suppl. 457. March-June. 



P. Sullivantii Aust. "Light sandy soil in fields. Spores in 

 spring. Orange," Bry. Ct. 



P. palustre Br. & Sch. "Old fields, N. J., James," Muse. 

 App. 55; Flushing, L. Id.!! Spring. 



Subfamily Ditricheae 



Plants short or tall; leaves lanceolate-subulate without en- 

 larged alar cells; capsule oval to cylindric, erect or nearly so; 

 peristome of sixteen narrow teeth, which are often cleft to the 

 base into thirty-two filiform cilia. 



