26 KEY TO THE FAMILIES. 



Subdivision 2.—ANGIOSPERMS. 



Class L— MONOCOTYLEDONS. 

 A. Marsh or water plants. 



B. Perianth absent ; seeds albuminous. 



Tall aquatic plants : flowers in dense velvety spikes. . Typhaceae 13. 

 Minute floating plants, with leaf-like laminas. often 



bearing roots on the under surface Lemnaceae' 23. 



B. Perianth usually present ; seeds exalbuminous. 



C. Perianth of few segments or wanting ; stamens and 

 carpels usually 1-4 . water-plants. 



Leaves entire ; perianth of 4 segments or wanting Potamogetonaceae 14. 

 Leaves toothed ; female perianth a cup-shaped 



bract Najadaceae 15. 



C. Perianth of 2 petaloid segments; stamens 6-18; 



carpels 3-6 ; water-plants Aponogetonaceae 16. 



C. Perianth of 6 herba ceous segments in 2 whorls ; anthers 



and fertile carpels 6 or 3 ; marsh plants Schetjchzeriaceae 17 



C. Perianth of 6 segments, the inner 3 petaloid ; marsh 

 plants. 



Flowers bisexual ; carpels 6 or more, free; ovary 



superior Alismataceae 18. 



Flowers mostly unisexual ; ovary inferior, 1- 

 celled (Halophila is a marine plant with incon- 

 spicuous perianth) Hydrocharitaceae 19. 



A. Mostly land plants ; sometimes growing near water ; seeds 



albuminous (except in Orchidareae). 



D. Perianth wanting; ovary superior, 1 -celled, 1-ovuled, 



each flower sheltered by small boat-shaped bracts 



called glume* ; leaves narrow (Order Glumiflorae). 



Stems hollow and interrupted by nodes ; leaf-sheaths 



slit downwards , flower enclosed in 2 bracts (Grasses) Gramineae 20. 

 Stems solid, without nodes ; leaf-sheaths not slit ; 



flower in the axil of 1 bract (Sedgt Family) Cyperaceae 21. 



D. Perianth present. 



E. Perianth conspicuous, of 6 segments in 2 rows, all, or 

 the inner ones, petaloid ; flowers usually bisexual. 

 F. Ovary superior, usually 3-celled. 



All the segments or lobes petaloid ; stamens 



usually 6 (Lily Family) Liliaceae 29. 



Outer segments irregular ; 3 inner segments 



united at base, yellow, perfect stamens 3 Xyridaceae 25. 



Three inner segments free, blue Commelinaceae 27. 



F. Ovary inferior. 



G. Flowers regular, or nearly so ; ovary 3-celled. 



Stamens 6 ; anthers opening inwards Amaryllidaceae 30. 



Stamens 3 ; anthers opening outwards (Iris 



Family) Iridaceae 31. 



G. Flowers usually irregular ; stamens and style 

 combined in a column ; ovary 1 -celled 



(Orchids) Orchidaceae 32. 



E. Perianth of glume-like segments, rarely wanting ; 

 ovary superior, 1 -3-celled. 

 H. Flowers bisexual ; segments 6 ; stamens 6 or 3 ; 

 ovules several in each cell ; leaves narrow, mostly 

 radical (Rushes) Jtjncaceae 28. 



H. Flowers bisexular or unisexual ; ovary with 1 

 pendulous ovule in each cell. 



Segments 6 or fewer ; stamens 3 ; leaves mostly 



reduced to sheathing bracts along the stem 



and split open on one side (Rush-like Plants) . . Restionaceae 23. 

 Segments reduced to 1-3 minute scales or absent ; 



ovary 1 or of several superposed carpels ; 



stamen 1 ; leaves filiform, radical ; small 



plants Centrolepidaceae 24. 



Segments small, 4-6 ; stamens 6 ; flowers in a 



head ; leaves radical Eriocaulaceae 26. 



