XVI ANALYTICAL KEY. 



CLASS II. GYMNOSPERM.E. Ovules naked upon a scale or 

 bract, or within open integuments. Mouoacious or dioecious trees or 

 shrubs. 



Male flowers in aments: female subsolitary, the ovule within a 

 double integument with small terminal orifice : nearly naked 

 dioscious shrubs. GNETACE^S, 89 



Female flowers in aments, becoming dry cones or berry-like : 

 ovules naked at the base of a scale : from shrubs to trees of 

 the largest size ; with needle or scale-like leaves. . . CONIFERS, 90 



SERIES II. PTERIDOPHYTA, or the FERN GROUP. Plants 

 without true flowers or seeds, but reproducing by spores ; and with a 

 distinct axis containing fibro- vascular bundles. 



Stems solid, leafy : sporangia in the axils of simple leaves or bracts. 

 Leaves long and grass-like from a corm-like trunk: spores 



of two kinds . * . ISOET^C, 91 



Small leaves imbricated upon a moss-like stem : sporangia in 



terminal spikes. 



Spores of two kinds : leaves with ligules. . . SELAGINELL^, 92 

 Spores of one kind : leaves without ligules. . LYCOPODIACE^E, 93 

 Stems solid, subterranean, bearing long-petioled often com- 

 pounded leaves (fronds). 

 Aquatics: leaves circinately developed: sporangia in fruits 



borne on the stem or petioles. .... RIIIZOCARPE.E, 94 

 Terrestrial : leaves erect in vernation : sporangia in special 



spikes or panicles OPHIOGLOSSACE^, 95 



Terrestrial : leaves circinate in vernation : sporangia on the 



under surface or margins of the leaves. . . . FILICES, 96 

 Stems hollow, jointed, and striate : leaves reduced to a toothed 

 sheath at the joints: sporangia in a terminal spike or 

 cone. . . . . . . . . . EQUISETACE.E, 97 



