OXALIDE.^. 55 



side curling back but remaining attached to the central 

 axis. 



About 300 species, chiefly in South Ahica, but also in 

 tropical South America. A few in Europe, Asia, tropical Africa 

 and North America. Several have been introduced as garden 

 plants, and because of the difficulty of eradicating the bulbs 

 some have become very troublesome weeds. 



The name is an old Greek o?ie, fro7n oxus, sharp, mid als, salt, in 

 allusion to the taste of the leaves. 



The leaflets fold inwards and downwards at night, showing as marked a 

 sleep-movement as occurs in the family leguminos/E. Charles Darwin 

 found that if such movement was prevented the leaves suffered (perhaps from 

 excessive radiation of heat to the sky, i.e., from cold), and thus demonstrated 

 the usefulness, to the plant, of this habit. The stamens and styles are 

 often of three different lengths, some plants of a species having short 

 styles and five medium and five long stamens, others with medium styles 

 and short and long stamens, others with long styles and short and medium 

 stamens. Charles Darwin showed by experiment that this was connected 

 with the cross-fertilization of the seeds by insects, pollen from long anthers 

 producing on the long st>led ovaries (necessarily of different plants) 

 better results than on short styled flowers (possibly on the same plant), 



[ No stem above ground, leaves and flower-stalks from a 



^J bulb d 



\ Stem above ground bearing leaves and flowers, creeping 

 [ and erect ^ l^ 



r Flowers solitary i to iJ4 inches red ; leaflets ^^ to i inch ; 



, J bulb or tuber dark and leathery. O. variabilis var rubra. 



I Flowers soilary yellow, or in few flowered simple or com- 



[ pound umbels. ^ . c 



' Leaflets 54 ^^ /^ i^^^h green ; flowers J^ inch pale yellow ; 

 ^, stem creeping slender, yellowish . . O. corniculata. 



j Leaflets J^ to i inch blotched with dark markings ; stem 



[ purplish creeping and erect .... O. pubescens. 



[ Leaflets four with dark markings ; bulb J^ to i inch 

 ^1 O. tetraphylla. 



} Leaflets three, green ; bulb Y^ inch . . O. latifolia. 



[ Leaflets three, spotted red ; flowers yellow O. pes-caprae. 



Oxalis corniculata Linn. ; F.B.I. \ 436, V I ; Yellow 

 Wood-sorrel. A small herb with slender stems running 

 horizontally on the ground. Leaf-stalks I to 3 inches 

 slender ; stipules pale and hairy, adnate to them ; leaflets 

 three, obcordate. Peduncles slender, ending in a single 

 flower, or an umbel ; pedicels ^ inch in the axils of linear 



