1913] Bartlett,— Systematic Studies on Oenothera 53 
of 1.3 mm. near the base to 3 mm. at the orifice, sparsely pubescent 
with a few arcuate hairs of type II and more numerous perpendicular 
hairs of type III. Calyx segments deflexed in pairs, about 23 mm. 
long and 4 mm. wide above the base, bearing slender, strictly terminal, 
red-tipped free appendages 3 mm. long, moderately pubescent, hairs 
of type II sparse near base but very abundant on the free calyx-tips, 
hairs of type III predominant except on the free tips, where they are 
lacking, hairs of type IV abundant on the free tips but absent else- 
where. Petals yellow, becoming darker on fading with a reddish area 
at the base, obcordate, 20 mm. long, 27 mm. wide. Stigma lobes 6-7 
mm. long, appressed, lying at the center of the unopened bud (there- 
fore shorter than the corolla after expansion) surrounded by the 
slightly longer anthers. Capsules loosely aggregated but still over- 
lapping in the lower part of the fruiting spike, rather more densely 
aggregated above, mostly between 23 and 27 mm. in length, shorter 
than the subpersistant foliaceous bracts except above, subquadrangu- 
lar, apices of the valves neither spreading nor conspicuously emargi- 
nate, sparsely pubescent with arcuate hairs of type II and densely 
viscid-puberulent with very short hairs of type III. Seeds light 
brown, rather large, 1.7 to 2 mm. long.— Seed received in 1910 from 
Professor de Vries with data as follows: “Oenothera biennis. Pure 
seed, fertilized by myself in my garden from plants whose parents 
were collected in the sand-dunes of Holland.... The pure race,— the 
biennis often contains the var. sulphurea.” Plants set out at Beth- 
esda, Md., in the spring of 1911 did not flower during that season and 
were winter-killed. Sister plants, however, flowered in the garden 
of Prof. B. M. Davis at the Bussey Institution, and were self-polli- 
nated by him. Their progeny, forced by being started in the green- 
house in the winter and set out early in the spring, flowered in 1912 
both at Philadelphia and Bethesda. Herbarium specimens; Bartlett 
2723, 3113 and 3160. 
Oenothera biennis var. sulphurea de Vries in litt. Formae speciei 
typicae omnino similis floribus pallidioribus sulphureis exceptis. An 
Lysimachia corniculata non papposa, Virginiana, major, flore sulphureo. 
Herm. (Hort. Lugd.-Bat. Cat. p. 396. 1687) et Lysimachia lutea. 
corniculata flore sulphureo Herm. (Florae Lugd.-Bat. Flores, p. 95.. 
1690) et Oenothera foliis ovatolanceolatis denticulatis, floribus lateralibus: 
in summo caulis, var. a, Linn. (Hort. Cliff. p. 144. 1737)? — Occur~ 
ring with the typical form in the sand-dunes of Holland. 
Bureau or PLaNT Inpustry, Washington, D. C. 
EXPLANATION OF THE PLATES. 
Plate 102. Lower figure: Oenothera biennis, mature rosette of a plant grown 
as an annual. 
Upper figure: The same plant in flower, showing the long branches of the 
lower axils and the simple inflorescence of the main axis. 
Plate 103. Branch and lower leaf of the same plant. 
Photographs by B. M. Davis, of “11.16 a biennis H,” in cultures grown 
from seeds of de Vries at the University of Pennsylvania, 1911. * 
