Key 



29 



Page 



Asteraceae . . Asteraceae — 205 



Flowers simple. 

 Stems square. 



(a) Leaves in whorls of 4 or 



7 . . Galium— 199 



(b) Leaves not in whorls of 

 4 of 7 



(1) Petals distinct or near- 

 ly so Houstonia— 198 



(2) Petals united in a tube 

 — See key to Men- 



thaceae Menthaceae — 180 



Stems not square, 

 (x) Petals or lobes of corolla 



4 or none. 



(a) Leaves united at base 



by a fringe of hairs Crusea — 198 



(b) Leaves not united as 

 in (a). 



(r) Spikes cottony Proelichia — 72 



(s) Flowers not in spikes. 



(1) Stamens 2. 



(m) Flowers solitary 

 in each of upper 



leaf -axils Veronica — 192 



(n) Flowers not soli- 

 tary Dianthera — 195 



(2) Stamens 4 Polypremum — 160 



(y) Petals or lobes of corolla 



5 or more. 



(a) Sap milky Asclepiadaceae — 162 



(b) Sap not milky 



(r) Petals distinct or 



nearly so. 



(1) Stems with sticky 



patches Silene— 78 



(2) Stems not sticky, 

 (m) Petals deeply 



notched Alsinaceae — 77 



(n) Petals not deeply 



notched Nemophila — 166 



(s) Petals united at base. 



