SEED-BEARING PLANTS 461 



The bright shining, yellow petals vary in number from 

 five to eight, and are much longer than the sepals; each 

 has a little scale at its base concealing a nectar-gland. The 

 simple pistils (carpels) are grouped in a round head, 

 surrounded by the numerous stamens (Figs. 344 and 345). 



FIG. 344. Plant of a buttercup (Ranunculus sp.). 



409. Spiral and Cyclic Arrangement. It will be re- 

 called that in the lower type of flower, characteristic of 

 the Gymnosperms, the sporophylls are arranged in spirals 

 on the flower axis. A study of the flower in Angiosperms 

 discloses a tendency for the flower parts to occur in 

 circles; the higher the plant in the system of classification 

 the more completely is the cyclic arrangement realized. 

 In the Crowfoot family there are some species, especially 



