46 Rhodora [Marca 
group. For example, species having small flowers with the O. biennis 
characters should be reckoned as belonging with the biennis series, 
even though they may have foliage more or less resembling 0. Lam- 
arckiana. This distinction is all the more important because the size 
of flower is usually correlated with other important flower differences, 
such as the habit of open- or close-pollination, while any of these 
flower characters may be found combined with any type of foliage. 
This manner of treatment does not mean, of course, that Linnaean 
species should be differentiated on the basis of single characters, for 
obviously that is not what is meant by the species, the unit of system- 
atists. 
Notwithstanding the fact that single characters must be resorted 
to in classifying large series of races under one or another Linnaean 
species, yet this method is not always applicable, for races occur which 
represent such distinct combinations of characters that they are at 
once recognized as worthy of specific rank. 
This is evidently the case with the species to be described in this 
paper. In its flower characters it belongs to the biennis series, yet 
in its foliage and its nearly glabrous character it clearly resembles 
O. argillicola Mack. But it possesses other features, such as the 
clearly subterminal sepal tips, which are reminiscent of another section 
of the genus. 
The plants from which this species is described, were grown this 
year at the John Innes Horticultural Institution, Merton, Surrey, 
from one of several packets of seeds collected at Ithaca, New York, 
by Mr. H. B. Brown in 1909 and sent to me through the kindness of 
Professor W. W. Rowlee of Cornell University. Some of the other 
packets collected from this region gave races very distinct from this 
and resembling much more the ordinary O. biennis forms. 
I at first intended giving this species the very appropriate desig- 
nation O. angustifolia, but since that name is now a synonym, having 
been used by Miller, I have substituted O. angustissima. "Type 
specimens from plants grown this year, are to be found in the British 
Museum (Natural History), London. The accompanying photo- 
graphs, kindly taken by E. J. Allard, illustrate a rosette and two flower- 
ing shoots together with three leaves from the mature rosette. The 
description is as follows: 
Oenothera angustissima, sp. nov. 
Leaves of mature rosette:— Length about 29 cm., greatest width 
