XVI ANALYTICAL KEY. 



Class II. GYMN0SPERM2E. Ovules naked upon a scale or 

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



shrubs. 



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

 double integument with small terminal orifice : nearly naked 

 dioecious shrubs. Gnetace.«, 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<£, 91 



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

 terminal spikes. 

 Spores of two kinds : leaves with ligules. . . Selaginelue, 92 

 Spores of one kind : leaves without ligules. . Ltcopodiace^, 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. .... Rhizocarpe^j, 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^j, 97 



