FLOWERS. 47 



as knotted water parsnep ; simple, when single flow- 

 ered, as in stone parsley ; and compounded, when 

 each main ray, as in fennel, branches at the summit 

 into a second and smaller umbel l . The focus of the 

 main rays has often below it one or more small flower- 

 scales, sometimes termed a fence 2 , and a similar smaller 

 flower-scale 3 often occurs at the junction of the smaller 

 umbels. 



Flowers. Centripetal evolution, a, tuft (clover) ; 6, catkin 

 (poplar) ; d, spike (foxglove) ; e, cylindrical spike (plantain) ; /, 

 forked spike (heliotrope) ; g, panicle (oats) j A, umbel with its 

 fence (carrot). 



(1) In Latin, Umbellula. 

 (2) In Latin, Involucrum. (3) In Latin, Involucellum. 



