KEY TO THE FAMILIES. 



1. Ovules not enclosed in an ovary (GYMNOSPERMAE). 2. 

 Ovules enclosed in an ovary (ANGIOSPERMAE). 4. 



2. Leaves pinnately compound, large. 1 CYCADACEAE. 

 Leaves simple. 3. 



3. Seeds drupe like, surrounded by a fleshy aril. 2 TAXACEAE. 

 Seeds in cones, dry. 3 PINACEAE. 



4. Vascular bundles scattered. Leaves usually parallel veined. 



Flowers usually 3-merous. (MONOCOTYLEDONEAE.) 5 



Vascular bundles in a ring. Leaves usually net veined. 



Flowers usually S-merous. (DICOTYLEDONEAE.) 30 



5. Perianth wanting or rudimentary, or (in Potamogeton) 



anthers with sepal-like appendages. 6. 



Perianth present, or rarely present in male, wanting in female 



flowers. 11. 



6. Flowers in the axils of chaff-like bracts arranged in spike- 



lets. 7. 



Flowers not in the axils of chaff-like bracts, etc. 8. 



7. Stems solid. Leaf sheaths usually not split. Seed not adnate 



to the pericarp. Anthers usually basi-fixed. 



10 CYPERACEAE, 



Stems usually hollow. Leaf sheaths split. Seeds adnate to 



the pericarp. Anthers versatile. 9 GRAMINEAE. 



8. Minute floating aquatics, without differentiation into stem 



and leaves. 13 LEMNACEAE. 



Plants differentiated into stem and leaves. 9. 



9. Ovaries several, separate or rarely 1 (in Zostera a marine 



plant). 5 POTAMOGETONACEAE. 



Ovary solitary. 10. 



10. Flowers surrounded by hairs. Seed coat not fleshy. 



4 TYPHACEAE. 

 Flowers not surrounded by hairs. Seed coat fleshy. 



12 ARACEAE. 



11. Ovary superior. I2. 

 Ovary inferior or half inferior. 24. 



12. Aquatic herbs with carpels 3 — 8, distinct. 



6 APONOGETONACEAE. 

 Carpels solitary or united, or if distinct then stem woody. 13. 



13. Perianth membranous, green or leathery, not petaloid. I4. 

 Perianth, at least the inner whorl, petaloid. 2O. 



14. Flowers in spadices. 15. 

 Flowers not in spadices. 16. 



