(Onagra biennis; Qenothera biennis of Gray) Evening-primrose


Flowers - Yellow, fragrant, opening at evening, 1 to 2 in.

across, borne in terminal leafy-bracted spikes. Calyx tube

slender, elongated, gradually enlarged at throat, the 4-pointed

lobes bent backward; corolla of 4 spreading petals; 8 stamens; 1

pistil; the stigma 4-cleft. Stem: Erect, wand-like, or branched,

to 1 to 5 ft. tall, rarely higher, leafy. Leaves: Alternate,

lance-shaped, mostly seated on stem, entire, or obscurely


Preferred Habitat - Roadsides, dry fields, thickets,


Flowering Season - June-October.

Distribution - Labrador to the Gulf of Mexico, west to the Rocky


Like a ballroom beauty, the evening primrose has a jaded,

bedraggled appearance by day when we meet it by the dusty

roadside, its erect buds, fading flowers from last night's

revelry, wilted ones of previous dissipations, and hairy oblong

capsules, all crowded together among the willow-like leaves at

the top of the rank growing plant. But at sunset a bud begins to

expand its delicate petals slowly, timidly - not suddenly and

with a pop, as the evening primrose of the garden does.

Now, its fragrance, that has been only faintly perceptible during

the day, becomes increasingly powerful. Why these blandishments

at such an hour? Because at dusk, when sphinx moths, large and

small, begin to fly (see Jamestown weed), the primrose's special

benefactors are abroad. All these moths, whose length of tongue

has kept pace with the development of the tubes of certain white

and yellow flowers dependent on their ministrations, find such

glowing like miniature moons for their special benefit, when

blossoms of other hues have melted into the deepening darkness.

If such have fragrance, they prepare to shed it now. Nectar is

secreted in tubes so deep and slender that none but the moths'

long tongues can drain the last drop. An exquisite, little,

rose-pink twilight flyer, his wings bordered with yellow,

flutters in ecstasy above the evening primrose's freshly opened

flowers, transferring in his rapid flight some of their abundant,

sticky pollen that hangs like a necklace from the outstretched

filaments. By day one may occasionally find a little fellow

asleep in a wilted blossom, which serves him as a tent, under

whose flaps the brightest bird eye rarely detects a dinner. After

a single night's dissipation the corolla wilts, hangs a while,

then drops from the maturing capsule as if severed with a sharp

knife. Few flowers, sometimes only one opens on a spike on a

given evening - a plan to increase the chances of

cross-fertilization between distinct plants; but there is a very

long succession of bloom. If a flower has not been pollenized

during the night it remains open a while in the morning.

Bumblebees now hurry in, and an occasional hummingbird takes a

sip of nectar. Toward the end of summer, when so much seed has

been set that the flower can afford to be generous, it distinctly

changes its habit and keeps open house all day.

During our winter walks we shall see close against the ground the

rosettes of year-old evening primrose plants - exquisitely

symmetrical, complex stars from whose center the flower stalks of

another summer will arise.

Floriform sunshine bursts forth from roadsides, fields, and

prairies when the COMMON SUNDROPS (Kneiffia fructicosa; formerly

Qenothera fructicosa) - is in flower. It is first cousin to the

similar evening primrose of taller, ranker growth. Often only one

blossom on a stalk expands at a time, to increase the chances of

cross-fertilization between distinct plants; but where colonies

grow it is a conspicuous acquaintance, for its large, bright

yellow corollas remain open all day. Bumblebees with their long

tongues, and some butterflies, drain the deeply hidden nectar;

smaller visitors get some only when it wells up high in the tube.

As the stigma surpasses the anthers, self-fertilization is

impossible unless an insect blunders by alighting elsewhere than

on the lower side, where the stigma is purposely turned to be

rubbed against his pollen-laden ventral surface when he settles

on a blossom. Unable to reach the nectar, mining and leaf-cutter

bees, wasps, flower flies, and beetles visit it for the abundant

pollen; and the common little white cabbage butterfly (Pieris

protodice) sucks here constantly. The capsules of the sundrops

are somewhat club-shaped and four-winged, angled above, with four

intervening ribs between. Range from Nova Scotia to Georgia, west

beyond the Mississippi.

A similar, but smaller, diurnal species (K. pumilla), likewise

found blooming in dry soil from June to August, has a more

westerly range North and South.