EVENINGPRIMROSE NIGHT WILLOWHERB
(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
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.
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