142 OUR NATIVE FERNS AND THEIR ALLIES. 



ana {Drictninond); Aspalaga, Florida {Curtiss, No. 3799 in 

 part). 



** Sfems densely tufted, rolling into a nest-like ball when dry ; 

 roots confined to base of stents. 



7. S. lepidophylla Spring. Stems 2' — 4' long, densely 

 Lufted, pinnatel)' branched to the base, the pinnae ascending, 

 sub-flabellately compound ; leaves of the lower plane closely 

 imbricate, ascending, obliquely ovate, obtuse, thick, rigid, mi- 

 nutely ciliate, green above, paler below, becoming reddish-brown 

 in age ; leaves of upper plane nearly as long, obliquely ovate, 

 obtuse; spikes 3" — 6" long, quadrangular; bracts deltoid, 

 acutely keeled. Texas to Arizona. 



8. S. Pringlei Baker. Outer stems 3' — 4' long, the inner 

 gradually shorter, flabellately branched, light green above, pale 

 below ; branchlets close, i" — 2" wide ; leaves of the lower plane 

 crowded, oblong, about i' long, including the conspicuous horny 

 white awn ; leaves of upper plane slightly smaller, somewhat 

 oblique; spikes short with uniform bracts. Chenate Moun- 

 tains, Texas {Nealley). 



S. pi I if era A. Br. is reported by Mr. Baker from Texas, but 

 it has not been found there recently. 



ORDER VIII. ISOETACEiE. 



Plant-body consisting of a bilobed or trilobed trunk emitting 

 dense tufts of roots, and sending up a compact rosette of rush- 

 like leaves, submerged, amphibious or sometimes growing in 

 moist soil. Sporangia sessile in the a.xils of the leaves, some 

 containing macrospores and others microspores. Contains a 

 single genus widely distributed. 



I. ISOETES L. QuiLLWORT. 

 Stem or trunk a more or less depressed, fleshy corm, rooting 

 just above its bilobed or trilobed base, covered above with the 

 dilated and imbricated bases of the awl-shaped or linear leaves. 

 Sporangia large, orbicular or ovoid, plano-convex, very thin, 

 .sessile in the axils of the leaves and united at the back with 

 their excavated bases ; those of the outer leaves filled with 

 spherical macrospores ; those of the inner leaves filled with 

 minute and powdery, grayish, obliquely oblong and triangular 



