Vascular Plants of North Carolina
Account for Narrowleaf Sundrops - Oenothera fruticosa   L.
Members of Oenothera with account distribution info or public map:
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Section 6 » Order Myrtales » Family Onagraceae
AuthorL.
DistributionPresent over the entire state, and presumably occurs in all 100 counties.

This is a widespread species, from eastern Canada south to central FL and LA.
AbundanceCommon nearly statewide, perhaps slightly less numerous in the foothills and mountains.
HabitatThis is a species mainly of dry to somewhat mesic forest borders, open woods, glades and barrens, margins of outcrops, and other similar upland openings and edges.
PhenologyBlooms from April to August, and fruits soon after flowering.
IdentificationThis species is an erect herb that grows to 1-2' tall, with a few small branches in the upper portions. The alternate stem leaves are rather scattered, lanceolate to narrowly elliptic, about 2" long and 1/4" wide, with entire margins. The quite large flowers grow from upper leaf axils, generally in a dense inflorescence, with 4 bright golden-yellow obovate petals that produce a flower about 1.5" across. Each petal has a notch at the apex, thus a flower looks like it has 8 lobes. Normally, this would be a very easy species to identify, as common as it is. However, in the western part of the state the extremely similar O. tetragona is present, in good numbers. That species has its capsules oblong or elliptical, widest near the middle; O. fruticosa has the capsule clavate or obovoid (club-shaped), widest above the middle. Also, O. tetragona has glandular hairs on the capsule, whereas O. fruticosa has hairy not glandular capsules. Lastly, Weakley (2018) says that O. tetragona has leaves more or less dentate, versus generally entire in O. fruticosa. Note that each of these two species has multiple varieties in the state, and these features may not apply to some of the rarer varieties! Of these distinctions, the shape of the capsule is going to be the most useful character -- elliptical/oblong in tetragona versus club-shaped (wider toward the apex) in fruticosa. This is an easily encountered species in the state, and hopefully you can make an identification from the capsules, if any are present. But, if one of these showy, knee-high plants is seen in the eastern two-thirds of the state, is almost surely will be O. fruticosa.
Taxonomic CommentsWeakley (2018) gives three varieties of the species in the state. The nominate var. fruticosa is present commonly statewide; var. microcarpa is rare in the Coastal Plain and found in "Boggy depressions"; and var. unguiculata is uncommon and found only in the Coastal Plain, in "Sandhills, moist to wet loamy savannas" (Weakley 2018).

Other Common Name(s)Southern Sundrops, Narrowleaf Evening-primrose, Yellow Sundrops
State RankS5
Global RankG5
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