194 University of California Publications in Botany [^^oi.. 10 



If the Californian species were grouped according to the method 

 outlined above they would segregate into five or six genera, largely 

 on the basis of single characters which are of doubtful generic 

 importance. The appearance of intergrades also presents an objec- 

 tion. For example, Lotus oMongifolius Greene var. cupreus of the 

 subgenus Hosackia, with its short leaves of three to seven leaflets, its 

 small flowers with petal claws approximate, and its few-flowered 

 umbels (mostly 1 to 3), more closely resembles some of the species 

 within the subgenus Acmispon than it does the other species of the 

 subgenus Hosackia. Lotus micranthus Benth. is another of these 

 troublesome species and has been disposed of in different ways by the 

 various authors. 



It has been suggested that the Old World genus Lotus is used in 

 too restricted a sense and that it should be extended to include several 

 other closely related genera. With reference to this point, Greene 

 (1890) states: "Lotus Tetragonolobus, Lotea, Krokeria and Dory- 

 cnium of the Old World along with Acmispon, Anisolotus, Hosackia, 

 and Syrmatium of the New World are even more naturally of one 

 genus than are the various subdivisions of the one genus Trifolium 

 as now everywhere received." If we accept the view that the New 

 World species are not sufficiently diverse to be referred to different 

 genera, but constitute a natural generic group, we have next to con- 

 sider whether the American species are generically distinct from the 

 Old World genus Lotus, as used in the broader sense indicated above, 

 or whether they form merely a part of it. 



As a result of careful study of the literature and of available 

 plant material, we find that the American species as a group possess 

 no constant characters of inflorescence, flower, or fruit which dis- 

 tinguish them generically from the European Loti as conceived by 

 Greene. The most nearly constant character that has been used in 

 separating the two groups relates to the leaves. The typical leaf in 

 the Old World species is pinnately compound with three leaflets at 

 the apex of the rachis and two at the base of the leaf, close to the 

 stem, simulating stipules. The leaves of the New World species are 

 far from uniform in the number and arrangement of the leaflets. 

 They vary from pinnately to subpalmately compound with the leaflets 

 ranging in number from three to fifteen or more. According to the 

 usage adopted in the present paper distinct stipules are always 

 present in the subgenus Hosackia, while in the subgenera Acmispon 

 and Syrmatium the stipules are reduced to glands. The leaves of 



