Download Oenothera - Missouri State University

ONAGRACEAE
Oenothera spp., Primrose*
e – no – the - rah
Description: Around 120 species of
annuals, biennials and perennials with
bright but short-lived flowers with 4
delicate petals and a long basal tube.
 Origin: United States and Canada.
 Height x width: 4 inches to 4 feet,
depending on the species.
 Growth habit: Prostrate to upright,
depending on the species.
 Foliage: Narrow leaves, alternate, and
sessile or stemless, depending on
species.
 Flowers: Four petals, usually yellow but
sometimes white or pink. Individual
flowers are short-lived but plants
produce many flower buds. Flowers of
many of the Oenothera species open in
the evening (“vespertine flowering”) and
are often called evening primrose. Other
species’ flowers are open during the day
and may be referred to sundrops.
Culture: Full sun or partial shade and well-drained soil. Usually drought tolerant.
Pests and problems: Root rot in wet soils is possible with some species.
Uses: Groundcover, trailing over walls and raised beds, border.
Other facts of interest: Plants in the Onagraceae family
bear flowers with 4 or 8 petals and 4 sepals, an
uncommon number. The sepals are reflexed behind
open flowers, resembling pennants in the wind, says
herbaceous plantsman Allan Armitage.
Propagation: Seed, division.
Species:
o O. biennis, Common Evening Primrose. Leafy,
erect branched stems and large yellow flowers
that open in the evening. Plants can reach 8 feet
in height but are usually shorter. Biennials that
often reseed. Native to Eastern North America.
Have naturalized in Europe where they are
called German Rampion.
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o O. fruticosa, Sundrops.
Reddish, slender, hairy
stems with lance-shaped,
sessile, hairy leaves that
are 1 to 3 inches long. Basal
leaves are slightly larger.
Plants can grow more than
1 foot tall. Flower buds are
erect, and open to a
terminal cluster of bright
yellow flowers, 1 to 2
inches wide. Flowers are
open during the day. The
seed capsule is shaped like
a club, tapering to a slender stalk. Native to Eastern North America.
o O. missouriensis, Ozark Sundrops (shown in picture at top of previous page).
Also known as O. macrocarpa. Short reddish stems with upright growing tips
on spreading stems. Leaves have petioles and are 1 to 4 inches long. Plants
are less than 1 foot tall. Flowers, open during the day, are bright to lemon
yellow, up to 5 inches in diameter, and persist for many days. Sepals often
have red spots in the bud stage and may retain the spots when the flowers
open. The seed capsule is
ellipsoid and winged. Not as
heat tolerant as some
primrose species, and should
be mulched in winter. Native
to Missouri and Kansas, south
to Texas.
o O. speciosa, Showy Evening
Primrose/Pink Primrose.
Rhizomatous and spreads
more rapidly than many other
primrose species. Leaves are
linear, 1 to 3 inches long,
pinnately lobed, and softly
hairy. The plant can grow
more than 1 foot tall.
Flowers, open during the day,
are 1 to 2 inches in diameter
and appear in the axils of the
upper leaves. Flowers open
white but mature to a pink
color. Native to the
Southcentral United States.