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1913]  Bartlett,— Systematic Studies on Oenothera,— ITI 85 
Free tips of the calyx segments bright red. Petals of very delicate 
texture, somewhat plicate, quickly wilting. 
Oenothera nutans. Rosette leaves crinkled, red-spotted, with red- 
dish mid-vein, not becoming uniformly red in the winter, outer ones 
slightly sinuate-dentate. Stem red and green, channeled, with red- 
tuberculate hairs. Leaves moderately pubescent on both sides. 
Bracts yellowish-green or nearly colorless, short, quickly deciduous. 
Free tips of the calyx segments green. Flower of delicate texture, 
quickly wilting and then nodding; petals somewhat plicate. 
Oenothera pycnocarpa. Rosette leaves flat or only somewhat 
crinkled, green, white-nerved, outer ones deeply pinnatifid. Stem 
green, nearly terete, with red-tuberculate hairs. Leaves rather 
densely pubescent on both sides. Bracts leaf-like, persistent. Free 
tips of the calyx segments green. Flowers of firm texture, not wilting 
quickly, and not noticeably nodding when wilted. Petals not plicate. 
Oenothera angustissima, is not closely related to the two other 
species. It has its nearest allies in two undescribed species which are 
known in Maryland and Virginia and which doubtless have a wider 
distribution. 
Oenothera nutans and Oenothera pycnocarpa would be placed by 
most botanists in Oenothera biennis. Both of them differ from that 
species, as it is interpreted in the last article of this series, in the mode 
of branching. Oe. biennis has either an inflorescence-bearing branch 
or a flower in every axil. The leaves grade uniformly into the bracts 
so that the lower flowers are much exceeded in length by the leaf-like 
bracts which subtend them. Oe. nutans and Oe. pycnocarpa agree 
in that the long basal inflorescence-bearing branches are separated 
from the inflorescence of the primary stem by an interval in which 
the leaf-axils are occupied by abbreviated, frequently rosette-like, 
vegetative branches. Prof. Atkinson has in preparation a paper 
on hybrids of these two species which will include illustrations of the 
type plants. 
Bureau or PLANT Inpustry, Washington, D. C. 
