FILICES. 121 



very minute, divided almost to the centre into a few beaded 

 hairs. Arizona, Utah, Colorado, Oregon, and northward. 



6. W. Mexicana Fee. Stipes 2' 3' long, smoothish or 

 with a few scattered scales ; fronds 3' 9' long, lanceolate ; 

 pinnae sub-opposite, triangular-lanceolate, pinnately divided 

 into finely-toothed segments, the teeth in young fronds ending 

 in delicate, semi-transparent, ciliated tips ; sori near the mar- 

 gin, broad, confluent ; receptacles dot-like, scales of indusium 

 four, laciniate, narrow, dividing at the end into articulated 

 hairs ; sporangia nearly sessile. Arizona, New Mexico. 



2. HYPOPELTIS Torr. Indusium conspicuous, at first en- 

 closing the sporangium, but early opening at the top and splitting 

 into several spreading jagged lobes. 



7. W. obtusa Torr. Stipes not jointed, 3' 6' long ; fronds 

 broadly lanceolate, minutely glandular-hairy, 6' 12' high, 

 nearly bipinnate; pinnae rather remote, triangular-ovate or ob- 

 long, pinnately parted ; segments oblong, obtuse, crenately 

 toothed, the lower ones pinnatifid ; veins forked. (W. Perrin- 

 iana H. & G., Aspidium obtusum Willd., Cheilanthes crenata 

 Kunze, Hypopeltis obtitsa Torr.) Smaller and more glandular 

 forms are var. glandulosa Eaton (W. Plummcrce Lemmon). 

 New England to Kentucky, Kansas, and Arizona. 



XXV. DICKSONIA L'Her. 



Sori small, globular, marginal or intra-marginal. Sporangia 

 borne in an elevated, globular receptacle, enclosed in a mem- 

 branous, cup-shaped indusium, which is open at the top, and 

 on the outer side partly adherent to a reflexed toothlet of the 

 frond. Named for James Dickson, an English botanist, 1738- 

 1822. Includes about 50 species, more than half of which are 

 arborescent. 



SITOLOBIUM J. Sm. 



i. D. pilosiuscula Willd. Rootstock slender, extensively 

 creeping, naked; stipes stout, chaffless ; fronds i 2| long, 

 5' 9' broad, ovate-lanceolate and pointed, usually tripinnatifid ; 

 pinnae lanceolate, pointed ; pinnules cut into oblong and ob- 

 tuse cut-toothed lobes; rachis and under surface minutely 

 glandular and hairy; sori minute, each on a recurved toothlet, 

 usually one at the upper margin of each lobe. (D. punctiloba 



