Part 1, 1909] SCHIZAEACEAE 39 
or distichous and dorsal upon a creeping rhizome, mostly erect or ascending, the laminae 
mostly free-veined, pinnatifid to pinnately decompound, some of them wholly fertile (the 
fronds thus dimorphous), or with only the basal pair of pinnae fertile, these usually elon- 
gate and erect or nearly so, commonly surpassing the sterile portion of the lamina; spo- 
rangia borne in a close single row upon either side of the ultimate divisions of the fertile 
pinnae, these usually either very slender and semi-terete (the sporangia thus non-indusi- 
ate), or narrowly foliose and functioning as indusia; spores triplanate. 
Type species, Osmunda Phyllitidis 1. 
Fronds in several ranks, only the basal pinnae fertile. 
Fertile pinnae at or near the base of the sterile lamina; indusium wanting. 
Veins anastomosing or casually connivent. 
Veins copiously anastomosing, the areolesample; pinnae rounded 
at the base. 1. A. Phyllitidis. 
Veins mostly free, casually connivent; pinnae smaller, mostly 
cuneate. 2, A.Underwoodiana. 
Veins invariably free. 
Pinnae not incised. 
Sterile lamina obtuse or truncate, less than 10 cm. long. 
Stipes of fertile fronds much shorter than the sterile fronds. 3. A. humilis. 
Stipes of fertile fronds mostly surpassing the sterile fronds. 
Leaf-tissue rigidly coriaceous, lustrous above ; margins 
subentire or undulate. 4. A. oblongifolia. 
Leaf-tissue membranous, opaque ; margins denticulate- 
crenate. 5. A. obovaia. 
Sele lamina acutish to acuminate, usually more than 10 cm. 
ong. 
Sterile lamina of a deltoid type; leaf-tissue long-pilose, 
especially above. 6. A. hirta. 
Sterile lamina oblong-lanceolate ; leaf-tissue glabrate or mi- 
nutely hispid above. 
Sterile lamina about 17 cm. long, 5.5 cm. broad, shorter 
than the fertile pinnae. 7. A, affinis. 
Sterile lamina 27-29 cm. long, 9 em. broad, much longer 
than the fertile pinnae. 8. A. Donnell-Snitthiz. 
Pinnae (at least the lower ones) incised, cleft, or pinnatifid. 
Pinnae deeply cleft, the segments distant and narrow. 9. A. hirsuta, 
Pinnae crenately incised or lobed, the lobes often shallow. 
Pinnae narrowly oblong to oblong-lanceolate, the lower 
ones lightly crenately incised. 10. A. pastinacaria. 
Pinnae broadly oblong to rhombic-ovate, the lower ones 
crenately lobed. 11. A. jaliscana. 
Fertile pinnae borne distinctly below the base of the sterile lamina ; 
indusiate. 
Fertile pinnae flattish, 7. ¢., the divisions not paniculate. 
Plants small, less than 5 cm. high. 12. A. Brandeget. 
Plants 50 cm. or more high. 13. A. aspera. 
Fertile pinnae greatly altered, the divisions paniculate. 
Pinnules of the sterile frond mostly anadromous, only those of 
the upper third of the lamina catadromous. 
Pinnules very obliquely incised or pinnatifid, the segments 
humerous, narrow, acute, serrate or pinnately incised. 14. A. anthriscifolia, 
Pinnules pinnately parted, the segments fewer, broader, ob- 
tuse, crenate or crenately lobed. 15. A. guatemalensis. 
Pinnules of the sterile frond mostly catadromous, only those of 
the basal pinnae anadromous. 
Stipe and rachis light-stramineous; fertile pinnae ascending, 
much shorter than the sterile lamina. 16. A. Roset. 
Stipe and rachis fuscous-stramineous; fertile pinnae erect, . 
surpassing the sterile lamina. 17. A. Karwinskyana. 
Fronds distichous, dorsal, dimorphous, or, if only the basal pinnae fertile, 
these remote from the sterile lamina; indusiate. 
Fronds dimorphous, 7. ¢., wholly fertile or sterile. 
Small or slender plants, the leaf-tissue firmly membranous. 
Sterile lamina bipinnate only at the base; segments narrowly eee 
obovate, long-cureate. _ 18. A. Wrightit. 
Sterile lamina bipinnate or tripinnatifid; segments rhombic- : : 
ovate to rhombic-oblong. . . A, cicularia. 
Stouter plants, the leaf-tissue rigidly coriaceous. : : 
Segments subentire or nearly so; fertile fronds 10-22 cm. long. 20. A. portoricensis. 
Segments sharply inciso-denticulate ; fertile fronds 25-45 cm. 
long. 21. A. aurila, 
g. F F 
Fronds not dimorphous, 7. ¢., only the basal pinnae fertile. 
Sterile lamina simply pinnate. . \ 
Leaf-tissue membrano-chartaceous, the veins elevated on both 
