448 



THE ROSALES 



spirally arranged. Thus, in the live-forever (Sedum), we have a 

 flower that has always been cited as the typical flower of the angi- 

 osperms. It is very regular with five whorls of alternating parts 

 of five members each, i. e.\ 5 sepals, 5 petals, 5 to 10 stamens 

 (one or two whorls) and usually 5 pistils (Fig. 310, A). This type 



D 



FIG. 310. Simple forms of the Resales: A, flower of Sedum, showing the 

 radial symmetry of the flower and five organs in each whorl. B, grass of 

 Parnassus (Parnassia), a member of a closely-allied family. C, flower on 

 first day of bloom, stamens converging over the pistil and encircled by row 

 of modified stamens. D, section of flower, showing slight growth of base of 

 receptacle and consequent adhesion to perianth. This flower is protandrous 

 and the stamens in shedding the spores straighten up one by one on succeed- 

 ing days and curve back towards the petals. The section shows three positions 

 assumed by the stamens. You may calculate the significance of these features. 



closely resembles the arrangement of parts in the buttercups, save 

 for the slight adhesion of the calyx and receptacle (Fig. 310, D). 

 These fleshy plants as illustrated in the houseleek (Fig. 69), hen 

 and chickens, etc., are very common forms of xerophytes. 



