690 FILICES (FERNS.) 



decurren* on the margined or winged rhachis ; indusium tapering or acute at 

 the free end. Shaded cliffs and rocky woods ; common and greatly varying 

 in the shape and cutting of the pinnules. July. (Eu.) 



15. O NOG LEA, L. (PI. 16 and 19.) 



Sporangia borne on elevated receptacles, forming roundish sori imperfectly 

 tovered by very delicate hood-shaped indusia attached to the base of the re- 

 ceptacles. Fertile fronds erect, rigid, with contracted pod-like or berry-like 

 divisions at first completely concealing the sporangia, and at last, when dry 

 and indurated, cracking open and allowing the spores to escape. Sterile 

 fronds foliaceous. Rootstocks creeping and constantly forming new plants. 

 (Name apparently from ovos, a vessel, and K\C(W; to close, from the singularly 

 rolled up fructification.) 



1. ONOCLEA proper. Sterile frond with anastomosing veins. 



1. O. sensibilis, L. (SENSITIVE FERN.) (PI. 19, fig. 1, 2.) Fronds 

 scattered; the sterile ones long-stalked (2-15' long), triangular-ovate, pin- 

 natifid into a few oblong-lanceolate sinuately lobed or nearly entire segments ; 

 veins reticulated with fine meshes ; fertile fronds contracted, closely bipinnate, 

 the pinnules rolled up into berry-like bodies. Moist meadows and thickets, 

 very common and variable. July. Imperfectly fertile fronds sometimes 

 occur, with the still foliaceous pinnae cut into obovate segments with free veins 

 and abortive sori ; the so-called var. OBTUSILOB\TA. 



2. STRUTHI6PTERIS. Sterile frond with free veins. 



2. O. Struthi6pteris, Hoffmann. (PI. 16, fig. 1-5.) Fronds growing 

 in a crown ; sterile ones short-stalked (2-10 high), broadly lanceolate, nar- 

 rowed toward the base, pinnate with many linear-lanceolate, pinnatifid pinnae ; 

 veins free, the veinlets simple; fertile frond shorter, pinnate with pod-like 

 or somewhat necklace-shaped pinnae. (Struthiopteris Germanica, Willd.) 

 Alluvial soil, common northward. July. The rootstock sends out slender 

 underground stolons, which bear fronds the next year. (Eu.) 



16. WOOD SI A, R. Brown. (PI. 19.) 



Fruit-dots round, borne on the back of simply-forked free veins ; the very 

 thin and often evanescent indusium attached by its base all around the recep- 

 tacle, under the sporangia, either small and open, or else early bursting at the 

 top into irregular pieces or lobes. Small and tufted pinnately-divided ferns. 

 (Dedicated to Joseph Woods, an English botanist.) 

 * Stalks obscurely articulated some distance from the base ; fronds chaffy or 



smooth, never glandular ; indusium divided nearly to the centre into slender 



hairs which are curled over the sporangia. 



1. W. Ilv6nsiS, R. Brown. Frond oblong-lanceolate (2- 6' long by 12- 

 18" wide), smoothish and green above, thickly clothed underneath as well as 

 the stalk with rusty bristle-like chaff, pinnate ; the pinnae crowded, oblong, ob- 

 tuse, sessile, piunately parted, the numerous crowded segments oblong, obtuse, 

 obscurely crenate ; the fruit-dots near the margin, somewhat confluent when 

 old. Exposed rocks; common, especially northward, and southward in the 

 Alleghanies. June. (Eu.) 



