TORTULACEAE 45 



TORTELLA (C. Mull.) Limpr. 



Usually growing in dense rather deep tufts, densely leaved. 

 Much like Barbula, but the leaves are cirrhate-crispate (except 

 T. fragilis) when dry, spreading to recurved, longer, elongated- 

 oblong to linear -lanceolate with margins plane or involute; costa 

 strong, ending in the apex or excurrent; upper leaf cells papil- 

 lose with large papillae; basal cells sharply differentiated from the 

 upper, hyaline, elongated and extending up the margins to a notice- 

 able extent, rectangular, linear near the margins; peristome well 

 developed and twisted. 



All our plants of this genus have previously been included in 

 Barbida by American authors. 



Key 



i — Leaves long lance-linear, obtusely acute, abruptly mucronate by the 



excurrent costa; monoicous caespitosa 



Leaves long-acuminate; dioicous 2 



2 — Leaves twisted crispate when dry, of one layer of cells throughout. 



tortuosa 

 Leaves erect, rigid, much less contorted when dry, of two layers of 

 cells above fragilis 



T. caespitosa (Schwaegr.) Limpr. "About the roots of trees, 

 common," Muse. App. 127; Closter, Pompton, Palisades, N. J., 

 Austin, Bx!; Richmond, S. Id., E. G. B., Southampton, L. Id., 

 both at Bx!; Sandy beach, Orient, L. Id., Latham. Spring. 



T. fragilis (Drumm.) Limpr. " Dry limestone rocks at the 

 New Jersey Zinc Mines," Muse. App. 129. 



T. tortuosa (L.) Limpr. "On rocks, common," Muse. App. 

 128. Usually sterile. 



Subfamily Pottieae 



Leaves broad in outline and narrowed toward the base. Costa 

 excurrent in most species. Calyptra cucullate; capsules gym- 

 nostomous (in our species). 



POTTIA Ehrh. 



Plants short, rarely branched, scattered or in tufts. Leaves 

 soft, broad in outline, enlarging upwards, ovate to oblong, 

 usually papillose (but not so in our most common species), 



