70 MOSSES WITH A HAND-LENS 



B. CONVOLUTA Hedw., the Sheathing Barbula, is next to the 

 preceding our most common Barbula. The plants are slender, less 

 than Y^ an inch high, densely csespitose, yellowish green. The 

 leaves are erect-spreading when moist, crisped when dry, oblong- 

 lanceolate to lingulate, obtuse to obtusely acute. The costa ends 

 in or below the apex, very rarely excurrent into a minute point. 

 The margin of the leaf is said to be slightly recurved at base, 

 but this character is very hard to demonstrate. The perichaetial 

 leaves are long-sheathing, convolute, inner without costa. The 

 seta is ^4 to i inch long, slender, straw colored or becoming red- 

 dish with age, and the peristome several times twisted. The 

 spores mature in spring. On soil, especially in limestone regions, 

 in rather dry places. 



At first sight this species reminds one of Ceratodon, but the 

 longer operculum, yellowish seta, and convolute perichaetial leaves 

 easily distinguish it, even with a hand-lens. 



TORTELLA. 



Much like Barbula except for the differences enumerated 

 under that genus. The plants are usually larger with longer, 

 plane-margined leaves, and grow in denser, often densely radi- 

 culose tufts. 



T. CAESPITOSA (Schwaegr.) Limpr. strongly resemble Bar- 

 bula unguiculata, but the leaves are much longer, with plane mar- 

 gins and hyaline cells running up the margin. It is common on 

 roots of trees and on soil in woods. The spores mature in 

 spring. 



T. TORTUOSA (L.) Limpr. The plants of this species are 1-3 

 inches in height, densely radiculose with red-brown filaments, 

 stout, growing in dense rounded tufts, pale or yellowish green 

 above, light brown below. The leaves are crowded, very long 

 ( l /4 inch), linear-lanceolate, tapering gradually to the slenderly 

 acute apex, spreading and flexuose when moist, very strongly 

 crisped, and often spirally contorted when dry. The costa is 

 excurrent into a short acute point, hyaline area at base large and 

 extending obliquely far up the margin. The seta is l / 2 to i inch 

 long, red below, paler above. The spores mature in late spring. 

 Common on rocks, especially limestone, perhaps the most com- 

 mon species of the family except Weisia viridula, but fruiting 



