ANALYTICAL KEYS TO THE FAMILIES. 



Plants with woody bundles, reproducing 



by spores. Phylum PTERIDOPHYTA, v. 



Plants with woody bundles, reproducing 



by seeds. Phylum SPERMATOPHYTA, v. 



Phylum PTERIDOPHYTA. 



Leaves few, large; stems mostly underground. 



Leaves 4-foliolate, clover-like; spore cases in closed 



pod-like sporocarps. Marsileaceae, 10. 



Leaves not 4-foliolate; spore cases not in sporo- 

 carps. 

 Spore cases in the tissue of a prominent and 



distinct fertile lobe of the leaf. Ophioglossaceae, 8. 



Spore cases formed of outgrowths from the 



surface of the leaf. Polypodiaceae, 1. 



Leaves numerous, small; stems aerial and under- 

 ground. 

 Leaves whorled; stems jointed, hollow. Equisetaceae, 11. 



Leaves not whorled; stems not jointed, solid. 

 Spore case in the enlarged base of the leaf; 



stems short, corm-like. Isoetaceae, IS. 



Spore case in the axil of the leaf; stems 

 elongated. 

 Spores all alike. Lycopodiaceae, 13. 



Spores of two kinds, large and small. Selaginellaceae, 14. 



Phylum SPERMATOPHYTA. 



Ovules and seeds not in a closed cavity, usually on the face of an open scale- 

 leaf; stigmas none. Class Gymnospermae, v. 

 Ovules and seeds contained in a closed cavity surrounded by one or more 

 closed and modified leaves forming an ovary; stigmas present. 

 Cotyledon one; stem with no distinction into bark, wood and pith {endog- 

 enous); leaves usually parallel-veined; parts of the flowers nearly 

 always in threes. Sub-class Monocotyledones, v. 

 Cotyledons two; stem (with rare exceptions) of bark, wood and pith 

 {exogenous); leaves usually net- veined; parts of the flower in fours, 

 fives or sixes, never in threes. Sub-class Dicotyledones, vi. 



Class GYMNOSPERMAE. 

 Fruit a cone. Pinaceae, 17. 



Fruit drupe-like. Taxaceae, 16. 



Class ANGIOSPERMAE. 



Sub-class MONOCOTYLEDONES. 



Plants small, floating, with no distinction of stem 



and leaves. Lemnaceae, 86. 



Plants with normal foliage. 



