22 DICRANACEAE 



chlorophyll toward the base, often special inflated cells at 

 the basal angles. Calyptra smooth, narrow, cucullate. Cap- 

 sule on an elongated seta, narrow, oval to cylindrical, frequently 

 cernuous; operculum usually long-beaked; peristome of 16 teeth 

 which are cleft half-way to the base or further into two lanceolate or 

 subulate divisions, usually of a reddish color, transversely barfed, 

 with fine vertical striae between the bars. There are a few cleis- 

 tocarpous species with capsules rounded and immersed or 

 elongated and exserted. 



The leaf character and the peristome when present will 

 usually indicate the family to one who is at all familiar with 

 it, but in some genera it is closely related to the Tortulaceae 

 [e. g., Ditrichum and Trichostomnm; Barbula (Didymodon) and 

 Ceratodon]. The plants of this family are inhabitants of soil 

 and rocks, rarely growing on trees, frequently on decaying wood. 



For convenience our genera may be grouped into eight tribes 

 or subfamilies. 



Key to Subfamilies of the Dicranaceae 

 i — Cleistocarpous; capsules spherical and immersed or pear-shaped and 



sometimes slightly exserted Bruchieae 



Capsules operculate and peristomes well developed 2 



2 — Plants large (with few exceptions) ; leaves with much enlarged and 



inflated alar cells Dicraneae 



Plants smaller; leaves without enlarged and inflated angular cells. ... 3 

 3 — Capsules with a long slender neck, sometimes longer than the urn 



Trematodonteae 



Capsules without a long neck 4 



4 — Rare minute plants of high altitudes or cool cliffs; teeth variable 



but not cleft to base Seligerieae 



Peristome teeth cleft to the base into two filiform legs (except 



Swartzia) Ditricheae, Oncophoreae 



Peristome dicranoid; plants like small Dicrana in appearance. 



Dicranelleae 

 Peristome various; upper leaf-cells minute, often papillose . . . Oncophoreae 



Subfamily Bruchieae 

 Small (8 mm. or less) yellowish- or brownish-green mosses, 

 growing upon soil in extensive tufts. Protonema often per- 

 sistent. Leaf cells not papillose and mostly elongated-rec- 

 tangular; alar cells not enlarged or inflated. Capsules cleisto- 

 carpous, subglobose and immersed, or pear-shaped and immersed 

 to fully exserted. 



