certain North American Convattariaceae. 
257 
Kansas and Minnesota. The striking distinctions are in the presence or 
absence of papillae on the perianth segments, and in the ventral surface of 
the leaves being glaucous or pubescent. U. grandiflora may possibly be 
a cell-giant of U. perfoliata which has since undergone two or three muta¬ 
tions, such as (1) loss of papillae from the perianth segments and (2) 
acquiry of pubescence instead of glaucousness. 
The genus Octkesia was formerly included in Uvularia^ to which it is 
closely related. It includes four species occupying much the same area as 
Uvularia. The common ancestor of the two genera probably had the 
sessile leaves and ovoid fruits of Disporum. One or more mutations pro¬ 
duced from this stock the perfoliate leaves of Uvularia, while another series 
of mutations led to the peculiar winged capsules, angular stem, and other 
features of Oakesia . The great similarity of the two genera in habit and 
flowers shows that there has been little extinction between them. 
The only other genus to which reference will be made here is Strep - 
topus , in which three American species are recognized. .S', amplexifolius 
and 5 . roseus make an excellent pair of species, as pointed out elsewhere. 1 
5 . longipes , Fernald, described in 1906, is at present known only from 
Michigan, New Hampshire, and Campobello Island, New Brunswick. It 
differs from .S', roseus chiefly in having trigonous instead of subglobose 
berries. The flowers may also be paler and the root-stocks longer and more 
slender, but these are fluctuating and inconstant characters. This form has 
probably originated from .S', roseus through a mutation, and furnishes a very 
good instance of a germinal change in which the main difference has arisen 
in one organ, with minor, more or less fluctuating differences in other parts 
of the plant. 
Most of the specific and generic characters considered in this paper as 
differentiating the members of the Convallariaceae are such as are unlikely 
to be of any advantage to the plant. They probably appeared as germinal 
variations, and have since been perpetuated and have enlarged in various 
directions their area of occupation. 
1 On Pairs of Species. Bot. Gaz., vol. Ixi, 1916, p. 185, Figs. 4, 5. 
S 
