A. W. Evans — North American Species of Frullania. 13 



6. Frullania riparia Hampe in Lehmann: Pugillus, vii, 14. 1838. 



Frullania molotis Mont, et Nees in Nees : Europ. Leberm., iii: 210. 1838 (nomen 

 nudum). 



Frullania ceolotis Nees in G. L. et N. Syn. Uep., 417. 1845. 



Plate V. 



Dioicous : plants growing in depressed tufts, green, sometimes 

 tinged with brownish : stems loosely and irregularly pinnate : leaves 

 distant to somewhat imbricated, the lobe ovate, slightly squarrose 

 when moist, arching over the stem and cordate at base, plane or slightly 

 decurved at rounded apex, entire or vaguely sinuate ; lobule when 

 inflated a galeate sac truncate at base, when explanate (the usual 

 condition) a small lanceolate lamina ; stylus minvite : underleaves 

 distant, rhombic to orbicular, bifid one-third or more with subacute 

 lobes and sinus, entire or subdentate on the edges : leaf -cells in mid- 

 dle of lobe with slightly thickened walls, distinct trigones and occa- 

 sional intermediate thickenings, the latter disappearing and the tri- 

 gones becoming more pronounced toward the base : ? inflorescence 

 terminal on the stem or a main branch ; bracts in two or three pairs, 

 deeply and unequally bifid, the lobe ovate, obtuse, entire ; lobule 

 shorter and narrower, lanceolate, acute, bearing a small tooth or 

 stylus on the inner edge near the base, otherwise entire ; bracteole 

 free from bracts, narrowly ovate, bifid about one third with subacute 

 lobes and narrow sinus, irregularly dentate or subentire on margin : 

 perianth and $ spike not seen. 



Stems 0-12"" in diameter ; lobes of leaves O-eO"^™ long, 0-48"™ 

 wide, lobules (when explanate) O'SO""'^ long, 0'12™™ wide ; under- 

 leaves 0-30"^™ long, 0-30™™ wide ; leaf -cells from edge of lobe0-015™"\ 

 from middle 0-018'"'" and from base 0-030™'° in diameter. 



On trees and rocks, mostly in shaded places ; from New England 

 westward to Minnesota and southward to the Gulf of Mexico. Dis- 

 tributed in Muse. Alleg. n. 268 (as F. dilatata, var. 2), in Hep. Bor,- 

 Araer. n. 101 (as^ ceolotis), and inHep. Amer. oi. IJfi (as F. ceolotis). 



Frullania riparia was first described from sterile material ; and, 

 although a description of the involucre is added in the Synopsis 

 Hepaticarum, the perianth and antheridial plant are apparently still 

 unknown. In the absence of these data it is not possible to point 

 out definitely the relationships of the species within the genus, but 

 the general characters of leaves and underleaves, the dioicous in- 

 florescence and the position of the female flowers show with little 

 doubt that it is a true Trachycolea. Its nearest relative seems to be 

 the Italian F. Cesatiana De Not.,* which is likewise incompletely 



1 Mem. Accad. delle Sci. di Torino, II, xxii : 383, pi- 5. 1865. 



