CUP FLOWERS 309 



gamosepalous and nearly regular. The carpel, which is 

 somewhat fleshy when young, on ripening becomes dry 

 and fibrous. This form of fruit is known as a "legume." 



567. It should be noted that the flowers of the plum 

 and the pea are very much alike in plan, the greatest 

 difference being the irregularity of the corolla, and the 

 fewer, united stamens. The pea represents an immense 

 group of plants (Bean Family) of 6,000 to 7,000 species, 

 which appear to have been developed from plum-like 

 ancestors by their corollas becoming irregular. They 

 constitute an evolutionary side line in which irregularity 

 of the corolla ("zygomorphy") has been especially 

 developed with reference to insect agency in pollination. 



568. The flower of the Garden Currant (Ribes) re- 

 minds one a little of that of the Apple. Its cup is deep 

 enough to enclose the ovary of the bicar- 

 pellary pistil. The carpels are united at 

 their margins, so that there is but one 

 cavity with two parietal placentae. The 

 margin of the cup bears the perianth (five 



sepals, five petals) and the five stamens. The ovary, 

 in ripening thickens and softens its wall, becoming a 

 many-seeded berry, a portion of which consists of the 

 thickened cup. 



569. The cup of the Evening Primrose 

 (Oenothera) is very deep, not only en- 

 closing the quadricarpellary ovary, but 

 extending as a tube much beyond it. The 

 carpels are wholly united so that the 

 ovary has four many-seeded cavities. The 

 eight stamens (in two whorls) are borne 

 on the edge of the tubular cup, as are 

 the four large yellow petals and the narrow, greenish 

 sepals. The ripening ovary becomes hard and dry, 



