122 OUR NATIVE FERNS AND THEIR ALLIES. 



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

 liairs. 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 (Spreng.) Torr. Stipes 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 obtusa Torr.) Smaller and more glandular 

 forms are var. glandulosa Eaton (^W. PlummercB Lemmon). 

 New England to Kentucky, Kansas, and Arizona. 



XXXI. DENNST^EDTIA Bernh. 



Sori small, globular, marginal or intramarginal. 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 Dennstaedt, a German botanist, 1738-1822. Includes 

 about 20 species, long confused with the arborescent genus 

 Dicksonia. 



% SiTOLOBIUM J. Sm. 



I. D. punctilobula (Michx.) Bernh. Rootstock slender, 

 creeping, naked; stipes stout, chaffless ; fronds 1° — 2|° long, 

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

 pinnae lanceolate, pointed ; pinnules cut into oblong and obtuse 

 cut-toothed lobes ; rachis and under surface minutely glandular 

 and hairy. {Dicksonia punctilobula Gray and former editions ; 

 D. pilosiuscula Willd.) Canada to Alabama. 



