KEY TO THE FAMILIES 



xiii 



KEY TO THE FAMILIES. 



Plants without flowers or seeds, but with spores 



which are borne in sporanges. 

 Plants not aquatic and leaves not linear and 



Sporanges in terminal spikes or panicles or 



on the back of a leaf. 

 Fronds erect in vernation. 

 Fronds circinate in vernation. 

 Sporanges opening vertically. 

 Sporanges opening transversely 

 Sporanges beneath scales in a terminal 



spike. 



Plants small floating aquatics. 



Plants with the leaves all linear and basal. ISOKTACEAE, 6. 

 Plants with flowers and seeds. 

 Ovules naked. 



Ovules enclosed in an ovary. 

 Seed with one cotyledon ; stems not differ- 

 entiated into pith, wood and bark ; 

 leaves usually parallel- veined. I. 



Seeds with two cotyledons ; stems differ- 

 entiated into pith, wood and bark ; 

 leaves usually netted-veined. II. 



OPHIOGLOSSACEAE, 1. 



OSMUNDACEAE, 2. 

 POLYPODIACEAE, 2. 



EQUISETACEAE, 6. 

 SALVINIACEAE, 5. 



PlNACEAE, 7. 



I. 



Carpels one or more, distinct. 

 Plants with true leaves. 

 Perianth of bristles or scales. 

 Flowers in terminal spikes. 

 Flowers in terminal round heads. 

 Perianth corolla-like. 



Leaves with parallel veins. 

 Carpels one-four. 

 Carpels numerous. 

 Leaves with netted veins. 

 Perianth none ; flowers in the axils of 



chaffy scales. 

 Glumes one for each flower ; fruit an 



achene ; stems solid. 

 Glumes two for each flower ; fruit a 



grain ; stems usually hollow. 

 Perianth none ; flowers not in the axils 



of chaffy scales. 



Minute floating plants with no leaves. 

 Carpels united into a compound ovary. 

 Ovary superior. 

 Perianth segments all green. 

 Herbs. 

 Climbing vines. 



TYPHACEAE, 7. 

 SPARGANIACEAE, 8. 



NAIADACEAE, 8. 

 ALISMACEAE, 9. 

 ARACEAE, 54. 



CYPERACEAE, 39. 

 GRAMINEAE, 11. 



ARACEAE, 54. 

 LEMNACEAE, 54. 



JUNCACEAE, 57. 

 SMILACEAE, 62. 



