POLYPETAL^— PAPILIONACE^ 137 



carpels open, and the seeds are violently thrown out as the strips 

 of the beak contract, so that their fruits are explosive capsules. 



OXALIDACE^ffi (Woodsorrel Family) 



This family is often included in the Geraniaceae. The 

 typical floral formula is the same in both families K5 C5 A5 + 5 

 G^). The Oxalidacese differ from Geranium in the following 

 respects : — (i.) The leaves are compound. (ii.) Often there 

 are more than two ovules in each of the five chambers of the 

 ovary. (iii.) There are five styles, (iv.) The capsular fruit 

 has no "beak." 



Type: WOODSORREL {Oxalis acetoselld). 



Herb with a rhizome, which is a true axis and not a 

 sympode. The leaves are compound, digitate, with three 

 leaflets. Note their day- and night- movements (figs. 249, 

 250). Inflorescence is cymose. Flowers @ white, (i.) The 

 petals are contorted in the bud. (ii.) The five nectaries are 

 opposite the petals, and lie between them and the five outer 

 stamens, (iii.) The plant produces small cleistogamic flowers 

 in addition to ordinary white ones. (iv.) The fruit is a 

 capsule dehiscing along the dorsal sutures : the seeds are 

 ejected violently from it by the elastic contraction of a white 

 fleshy coat which envelops each seed separately like an 

 outer testa. 



PAPILIONACEiE (Pea Family). 



Herbs or shrubs. Leaves alternate, stipulate, usually com- 

 pound. Flowers irregular, cyclic, weakly perigynous. Sepals 

 five, gamosepalous. Petals five, polypetalous, consisting of a 

 standard, two wings, and a kejel. Stamens ten, weakly 

 perigynous; filaments of all, or of all but one, combined. 

 Carpel one, superior. Fruit usually a legume. Seed non- 

 endospermic; 



Types : GARDEN PEA {Pisum sativum) : WHITE 

 CLOVER (Trifolium repens). 



Vegetative characters. — Herbs, with alternate compound 

 stipulate leaves. The Clover is a creeping perennial, its leaves 

 (figs. 251, 252) having three leaflets and two small stipules 



