POLYPODIACEAE 5 



ovate-lanceolate, short-stalked, somewhat leathery, smooth and manifestly glossy ; midrib 

 distinct, with oblique parallel veins: sporophylls long-stalked, overtopping the leaf. 



In dry soil, western and southern Texas and adjacent Mexico. 



2. Ornithopteris adiantifplia (L.) Bernh. Leaf-blades triangular-ovate, 12-20 cm. 

 long, on usually elongated petioles, slightly pubescent, pinnately decompound ; ultimate 

 segments obovate or cuneate, entire or lobed, striate above with numerous flabellate veins. 



In sandy soil or coral rock, peninsular Florida. Also in the West Indies and Mexico. 



FAMILY 4. CERATOPTERIDACEAE Underw. FLOATING FERN FAMILY. 



Aquatic succulent plants, floating, or rooting in the mud. Leaves of two 

 kinds, some with flat blades, the sporophylls narrowed, with broadly reflexed 

 margins meeting at the midrib. Sporanges scattered, sessile, each with a broad 

 complete partial or obsolete ring. Sori seated on tw6 or three veins that run down 

 the length of the leaf-blade, nearly parallel to both the edge and the midrib. 



1. CERATOPTBRIS Brongn. 

 Characters of the family. FLOATING FERN. 



1. Ceratopteris thalictroides (L. ) Brongn. Leaves tufted ; petioles inflated, filled 

 with large air-cavities ; blades floating, 15-35 cm. long, simple or only slightly divided 

 when young, 2-pinnate at maturity : sporophylls 2-3-pinnate, erect or ascending, the ulti- 

 mate segments pod-like. 



In deep or shallow water, peninsular Florida and Louisiana. Also widely distributed in the tropics. 



FAMILY 5. POLYPODIACEAE R. Br. FERN FAMILY. 



Plants various in habit. Rootstocks creeping or horizontal, elongated, or 

 short and erect. Leaves various, coiled in vernation : blades entire, pinnate, 

 pinnatifid or decompound. Sporanges borne in clusters (sori) on the lower side 

 or margins of the leaf-blades, stalked, provided with a vertical ring, open trans- 

 versely. Sori frequently with a membranous covering (indusium). Prothallia 

 green. 



A. Spqriferous leaf-blades flat, or their edges merely revolute. 

 Sori without indusia. 



Sori covering the leaf-blades or portions of them with a uniform layer. 1. ACROSTICHUM. 



Sori more or less separated from each other. 



Sori roundish, not more than twice as long as broad. 



Leaves with petioles jointed to the rootstocks ; blades entire, pin- 

 natifid or 1-pinnate. 



Veins free ; leaf-blades (in our species) pinnatifid or pinnate. 2. POLYPODIUM. 



Veins copiously anastomosing. 



Veins forming regular ample areolae : leaf-blades pinnatifid. 3. PHLKBODIUM. 

 Veins, or those parallel to the margins, forming irregular areo- 

 lae : leaf-blades simple. 



Leaves ample : veins parallel to the margins with interven- 

 ing finer areolae. 4. CAMPYLONEURON. 

 Leaves relatively small: veins with irregular areolae through- 

 out. 5. PHYMATODES. 

 Leaves not jointed to the rootstocks : blades (in our species) 2-3-pin- 



natifid or ternate. 



Veins free. 25. PHEGOPTERIS. 



Veins connivent, the branches of contiguous groups uniting to form 



one or more arches. 26. GONIOPTERIS. 



Sori linear. 



Leaf-blades simple. 



Leaves with very narrow grass-like blades : veins indistinct. 6. VITTARIA. 



Leaves with expanded blades : veins markedly anastomosing. 7. CHEILOGRAMMA. 



Leaf-blades 1-4-pinnate : sori marginal. 13. NOTHOLAENA. 



Sori with indusia. 



Indusia formed of the partially altered margin of the leaf-blade. 



Sporanges at the ends of veins, borne in a reflexed portion of the leaf- 

 blade. 10. ADIANTUM. 

 Sporanges borne on a continuous vein-like receptacle connecting the 



apices of the veins. 



Indusia single, formed of the altered leaf-margin. 8. PTERIS. 



Indusia double, a membranous one arising within the receptacle. 9. PTERIDIUM. 



Sporanges at the apices of unconnected veins or near them. 



Sori mostly forming a continuous indusium around the leaf-segments. 11. PELLAEA. 

 Sori minute; indusium usually interrupted, if continuous, leaf-seg- 

 ments small and bead-like. 12. CHEILANTHES. 

 Indusia specially developed, not from the leaf-margins : sori dorsal. 

 Sori linear or oblong : indusia more than twice as long as broad. 



