68 OUR NATIVE FERNS AND THEIR ALLIES. 



\\ Rootstock tuberous or globose; plants i' 2^' high. 



6. O. pusillum Nutt. Plants i' 4' high from a short slightly 

 tuberous rootstock; leaf small, cuneate-lanceolate or ovate, \ f 

 long, rising near the base of the stem ; basal veins 3, the midvein 

 branching by lateral veinlets which form narrow areolae with no 

 free veinlets; spikes i' i' long with 6 14 sporangia on either 

 side. (O. nudicaule of former edition not of L. fil., which is an Af- 

 rican plant; O. tenerum Mett.) Georgia to Florida and Louisiana. 



7. O. crotalophoroides Walt. Plants i' 4' high from a 

 large globose rootstock ; leaf \' ij' long, concave, broadly ovate 

 and cordate at base, the apex acute ; basal veins 5, the midvein 

 rarely branched, the lateral freely anastomosing, forming short 

 hexagonal areolae with rarely a free veinlet; spike short, broad, 

 ' i' long with 41 1 sporangia on either side. (O. bulbosiun 

 Michx.) South Carolina to Florida and Texas. 



II. CHEIROCLOSSA Presl. 



Sporangia large, coriaceous, coherent in two ranks on the 

 edges of simple or rarely forked spikes. Leaf palmately lobed, 

 irregular, bearing several spikes at or below its base. Veins 

 anastomosing. Spores copious. Epiphytic. Name from Gr. 

 Xeip, hand, and yXo<r<ra, tongue. A single tropical species. 



i. C. palmata (L.) Presl. Rootstock thick, tuberous, cov- 

 ered with fine woolly chaff ; leaf fleshy, 4' 8' long, on a stem 

 nearly as long, palmately divided into 2 9 broadly spreading 

 lobes, rarely simple and lanceolate ; basal veins 5 8, repeatedly 

 branching and anastomosing, forming long hexagonal areolae 

 without free veinlets; spikes i 16, on short stalks, i' or more 

 long; spores large. On palmettos, Florida and tropical America. 



III. BOTRYCHIUM Swz- GRAPE-FERN. 

 Rootstock very short, erect, with clustered fleshy roots, the 

 bud for the next year's growth usually imbedded in the base of 

 the stipe. Sterile segment of frond pinnately or ternately di- 

 vided or compound. Fertile segment i 3-pinnate, with double 

 rows of sessile, naked sporangia. Veins free. Spores copious, 

 sulphur-yellow. Name from Gr. fforpvs, a bunch of grapes, 

 alluding to the clustered sporangia. Contains about thirty 

 species, of which fifteen are found in our limits. 



