2 KEY TO PLANTS. 
with 6 perianth-leaves*), usually entire 
and narrow and sessile with a broad 
base. Flowers usually 3-merous. Em- 
bryo with a single cotyledon, rarely 
undivided. Monocotyledons. 
(b) Vascular bundles of the stem nearly always 
collected intoacylinder. Leaves usually 
net-veined, rarely rudimentary or want- 
ing, very rarely parallel-veined, seldom 
sessile with a broad base and at the same 
time entire. Flowers usually 4-5-mer- 
ous. Embryo with 2 cotyledons, rarely 
one of them rudimentary or the embryo 
undivided. (Dicotyledons.) 3. 
3 (a) Perianth-leaves wanting orresembling each 
other (especially in texture and colour), 
rarely somewhat unequal but not more 
than 5. Monochlamydeae. 
(b) Perianth-leaves separated in sepals and 
petals, rarely almost equal but together 
more than 5. 4., 
4 (a) Petals distinct throughout, rarely coherent 
above, but distinct below. Polypetalae. ae 
(b) Petals united below (at least at the base) 
or rarely throughout. Gamopetalae. » 104 
*The former in Aroideae, the latter in Dioscoreaceae, 
Taccaceae and Liliaceae. 
