F1LICES. 465 



smaller than the sterile, but having a thicker stipe ; segments incurved and filled 

 with the confluent son'. Common Ostrich-fern. 



15. DICKSONIA. L'Herit. Dicksonia. 

 (In honor of James Dickson, an English botanist.) 

 Sori small, roundish or dot-like, distinct, marginal. Indit- 

 sium coriaceous or membranaceous, formed in part of the lobule 

 of the frond and of the proper indusium more or less united, 

 2-valved or entire, sometimes cup-shaped. 



D. pilosiuscula Wiltd. : frond bipinnate ; pinnse lanceolate, sessile ; pin- 

 nules decurrent, ovate-oblong, pinnatifid; segments incised-toothed ; sori 

 solitary, minute ; indusium cup-shaped. D. pundiloba Hook. Nephrodium 

 punctilobum Mich. Aspidium punctilobum, Willd. 



Moist shady places. Can. to Virg. ; common. July. l^.. Frond 15 20 inches 

 high, lance-oblong, somewhat hairy, pale yellowish-green and rather delicate. 

 Stipe and rachis somewhat hairy, pale green. Sori solitary, minute, near the 

 divisions of the segments. Hairy Dicksonia. 



II. OSMUNDEJE. Capsules destitute of a ring, reticulated, striated 

 with rays at the apex, opening lengthwise and usually externally. 



16. OSMUNDA. Linn. Flowering Fern. 



(Etymology uncertain.) 



Spore-cases subglobose, pedicellate, radiate-striate or wrin- 

 kled, half 2-valved, in terminal paniculate racemes, or clustered 

 on the contracted frond. Indusium none. 



1. O. Claytoniana Linn.: frond pinnate; pinnae pinnatifid; segments 

 oblong, entire ; some of the intermediate pinnae fertile. O. interrupta 

 Mich. 



Low wet grounds. Can. to Virg. ; common. June. 7J.. Stipe nearly smooth, 

 6 8 inches long. Frond 18 24 inches long, linear-oblong in its outline ; pinna 

 mostly opposite, 2 or 3 of the central pairs contracted into pinnate clusters of 

 dark brown spore-cases. Interrupted Flowering-fern. 



2. O. spectabilis Linn. : frond bipinnate, fruit bearing at the summit ; 

 pinnules lance-oblong, nearly equal at the base, subpetiolate, serrulate ; 

 raceme large, decompound, smooth. O. regalis Mich. 



Moist meadows and thickets. Can. to Flor. July. "11-. Fern 34 feet high, 

 smooth, grayish-green, with numerous spreading branches. Raceme terminal, 

 48 inches long. Smaller and of a more rigid texture than the foreign O regalis, 

 and also differing from it in having the pinnules distinct and without the auricle 

 on the lower side. Flowering-fern. 



3. O. cinnamomea Linn. : sterile frond pinnate ; pinnae elongated, pin- 

 natifid ; segments ovate-oblong, entire ; fertile frond bipinnate ; pinnae con- 

 tracted, and with the stipe woolly. 



var. frondosa Torr. : frond leafy below, fruit-beanng at the summit ; 

 stipe less woolly. O. Claytoniana Conrad not of Linn, (according to 

 Torr.} 



