412 ORDER OXALIDE^E, OR WOOD-SORREL TRIBE. 



is undeveloped. The ovarium is made of five carpels clustered 

 together, their cavities remaining separate ; the stigma is sessile 

 on its top, as in the Poppy (. 523), and exhibits a greater or 

 less division into five parts. The Balsams usually grow in damp 

 places among bushes ; and one or two species are found in nearly 

 every quarter of the globe. 



577. Another small order, allied to the Geranium tribe, is 

 that of OXALIDE^E, or Wood Sorrel tribe ; which is chiefly de- 

 serving of notice, on account of an important product yielded by 

 some of its species. The Wood Sorrel (Oxalis) and its allies 

 are herbaceous plants, which abound most in the warmer tem- 

 perate regions, especially in America and at the Cape of Good 

 Hope; but two species are found in the woods and shady places 

 of this country. In the structure of their flowers, they differ 

 but little from Geraniaceae ; their calyx and corolla each con- 

 sisting of five equal leaflets ; their stamens being ten in number, 



arranged in two rows, of 

 which the outer one is the 

 longest ; and their ovaria 

 consisting of five adherent 

 carpels. The stamens are 

 generally united at the 

 base, however, into a single 



FIG. 152. DIAGRAM OF THE FIXHVER OF Ox- , ,, ., , 



AMDK^E. bundle ; there is no central 



axis in the midst of the 



carpels ; the styles are distinct ; and there is a minute but im- 

 portant difference in the structure of the seed. They are further 

 distinguished by the division of their leaves, which are generally 

 compound ; and, if simple, become so merely through the want 

 of development of some of the segments. In this group, as in 

 the Balsaminese and Geraniacese, there is a provision for the 

 scattering of the seeds by the sudden rupture of their integument, 

 which possesses elasticity enough to expel them with some force. 

 The Wood-Sorrel is one of the plants whose leaves droop very 

 evidently at night. The property which is most characteristic 

 of the Oxalideae is the acid nature of their juices, which is chiefly 

 to be noticed in the common Wood Sorrel of this country. The 



