EVENING PRIMROSE FAMILY ONAGRACEAE 
COMMON EVENING PRIMROSE 
Oenothera biennis L. 
The Common Evening Primrose grows abundantly in open 
places, usually in rather dry soil, from Labrador to Florida and 
west to Minnesota and Texas. This is a biennial that produces 
the first year only a rosette of 
leaves and a strong root. 
The fleshy root is said to have 
been used as a table vegetable 
long before potatoes were cul- 
tivated so universally. The 
rosette of leaves remains green 
all winter and in the spring 
there is produced an upright, 
leafy, more or less branched 
shoot that grows 1-6 feet high 
and bears the flowers and fruits. 
In Illinois this Evening 
Primrose begins blooming in 
June and continues until stop- 
ped by the frosts of October. 
y The beautiful and fragrant 
‘WN flowers open at sundown and 
ee \ are interesting to watch. They 
VSS close the following day and 
| Va so are pollinated by night- 
fe 
flying moths. The 4 bright 
yellow petals and 8 stamens 
are inserted on the long and 
narrow calyx tube, which is terminated by 4 narrow reflexed 
lobes. The style is slender and the stigma 4-lobed. The mature 
capsules are three-quarters to 1% inches long and are covered 
with short hairs. They contain as many as 40 seeds each, and a 
mature plant once examined was thus found to produce 500,000 
seeds. 
The Northern Evening Primrose, Oenothera muricata L., is 
commonly associated in this state with the above species, and is 
usually mistaken for it. However, it grows not more than 3 feet 
high instead of having the 6-foot range of the Common Evening 
Primrose, its leaves are narrower and more nearly entire, and above 
all, the hairs on its stems rise from reddish glands. 
210 
