LEGUMINOS^. 



467 



the same aestivation (Figs. 508-510) ; but in reality there is not a 

 single characteristic which absolutely distinguishes them from the 

 Papilionacea?. The majority are aborescent ; the leaves as a rule 

 are pinnate or bi-pinnate. The flower is 5-merous, most frequently 

 perigynous and slightly zygomorphic ; the calyx is free or 

 gamosepalous, the corolla polypetalous with ascending imbricate 

 (Estivation (i.e. the two lowest petals envelop the lateral ones, 

 and these again the posterior; Fig. 508) ; 10 free stamens; fruit 

 various. 



Cassia (Figs. 508-510) is the largest genus (about 200 species) ; 

 it has an almost hypogynous, zygomorphic flower with 5 free 

 sepals and petals ; of the 10 stamens the 3 posterior are generally 

 barren, the others are of very unequal length and open at the 

 apex by pores (Fig. 509). In some (the Senna group) the fruit is 



?iGr. 508. Floral diagram. 



FIGS. 608-510. Cassia flo rib urc da. 

 FIG. 509. Flower. FIG. 510. The same in long. sect. 



a flat, short, thin, dehiscing pod ; in others (Cathartocarpus) it is 

 round, long, woody or fleshy, indehiscent, and divided internally 

 by more or less fleshy transverse walls into as many cells as there 

 are seeds. The following also have DEHISCENT FRUITS : Bauliinia 

 (often lianes, tropical climbers with tendrils [stem-structures] and 

 anomalous stems), Copaifera, Hce.matoxylon (whose pod does not 

 dehisce along the suture, but laterally), Cercis (simple leaves; the 

 corolla resembles that of the Papilionacea3, but the posterior petal 

 is the smallest, and is enveloped by the 2 lateral ones, which are 

 enveloped in their turn by the 2 anterior). FRUIT INDEHISCENT: 

 Tamarindu* indica ; -the pod is almost round, often a little 

 abstricted between the seeds ; the wall is formed by a thin, 

 brittle external layer, enclosing an acid pulp ; well-dey eloped 



