434 ISOfiT^. (QUILLWORT FAMILY.) 



SERIES IT. 



PTERIDOPHYTA (Vascular Cryptogams), or 

 Ferns and their allies. 



Plants destitute of proper flowers, that is, having no sta- 

 mens and pistils, and not producing seeds. A distinct axis 

 containing fibro-vascular bundles, as does the foliage when 

 there is any. Sexual reproduction by means of antheridia 

 and archegonia, one or both of which is formed on a prothal- 

 lus which is developed from the non-sexual spore and upon 

 which the conspicuous but non-sexual plant is produced. 



Class I. LYCOPODINE^. 



Plants with a solid, dichotomously branched, leafy stem, 

 the leaves imbricated and often giving to the lower forms a 

 moss-like appearance, but may be distinguished from moss 

 leaves by their midrib. Sporangia in the axils of simple 

 leaves or bracts. 



Subclass I. HETEEOSPOEE^. 



Producing spores of two kinds, the larger {macrospores) 

 producing a prothallus with archegonia, the smaller (^nicro- 

 spores) producing a prothallus (rudimentary) with sperm-cells. 

 Leaves with ligules. 



Order 91. ISOET^E. (Quillwort Family.) 



Mostly aquatic plants, with a short solid corm-like stem (tninJc) and 

 elongated grass-like leaves, the bases of which are expanded and have 

 thin stipule-like infolded margins (the veluni), which enclose large 

 simple ovoid thin-walled sporangia; the outer ones containing large 

 spherical trivittate macrospores; those of the inner leaves filled with 

 very minute grayish triangular microspores. 



