146 



PARTICULAR FORMS OF FLOWERS 



answer in all ways to this description. The term perianth 

 is used in other plants than the Liliacese. 



296. Papilionaceous Flowers. In the pea and bean 

 tribes the flower has a special form 

 (Figs. 245, 246). The calyx is a shal- 

 low 5-toothed tube. The corolla is 

 composed of four pieces, the large 

 expanded part at the back, 

 known as the standard or 

 banner; the two hooded side 

 pieces, known as the wings', 

 the single boat-shaped part 



246. Flowers of alfalfa, 

 enlarged. 



247. 



Cassia flower, beneath the wings, known as 



showing the _. , . . 



the keel. The keel is sup- 



separate 



keel petals. posed to re p re s en t two united 



petals, since the calyx and stamens are in 5's or multiples 

 of 5; moreover, it is of two distinct parts in cassia (Fig. 

 247) and some other plants of the pea family. Flowers of 

 the pea shape are papilionaceous 

 (Latin papilio, a butterfly). 



297. Flowers of the pea and its 

 kind have a peculiar arrangement 

 of stamens. The stamens are 10, 

 of which 9 are united into a tube 

 which incloses the pistil. The tenth 

 stamen lies on the upper edge of the 

 pistil. The remains of these sta- 

 mens are seen in Fig. 206. The sta- 

 mens are said to be diadelphous ("in 

 two brotherhoods") when united into 

 two groups as in this case. Stamens 

 in one group would be called mona- 

 delphous, and this arrangement 



OCCUrS in SOme members Of the 

 T . < -1 



Legummosse or pea family. 



fruits, 

 "cheeses 



plant." 



a, gives the names 

 and "shirt button 



