Oenothera laciniata Hill.

Cut-leaved Primrose

Oenothera laciniata plant

Family - Onagraceae

Stems - From a big taproot, multiple from the base, ascending, herbaceous, solid, green, branching, to +50cm long, antrorse puberulent and antrorse villous (especially near the apex) (the hairs villous hairs with pustulate bases).

Leaves - Alternate, sessile or with short petioles to 2-3mm long, laciniate, oblong to elliptic or lanceolate in outline, to 9-10cm long, +/-2cm broad, pubescent with short and long hairs as the stem, flat-green above and below. The translucent-whitish midrib contrasting with the leaf tissue. Margins ciliate.

Oenothera laciniata leaves

Inflorescence - Sessile flowers from the leaf axils, one flower per leaf.

Flowers - Petals 4, pale yellow, obcordate, to 1.5cm broad and long, glabrous, borne at the apex of the flora tube. Stamens 8, erect, exserted, borne at the apex of the floral tube. Filaments glabrous, yellow, +/-1cm long. Anthers yellow, 5mm long, dorsifixed. Style 1, to +/-3.5cm long, translucent basally, yellowish apically, glabrous, mostly included in the floral tube but exserted +/-1cm. Stigmas yellow, 4, spreading, 5-7mm long. Sepals 4, linear-subulate, to -2cm long, +/-3mm broad at the base, glabrous internally, villous and glandular pubescent externally, remaining joined at the apices and reflexed to one side at anthesis. Floral tube to +/-2.5cm long, -2mm in diameter, villous and with short, glandular hairs, with a reddish tinge. Ovary cylindric, villous and with short antrorse puberulent hairs, 1.2cm long, -2mm in diameter (in flower), quickly expanding in fruit, green, 8-ribbed, with many ovules.

Oenothera laciniata calyxCalyx.

Oenothera laciniata flower

Flowering - May - October.

Habitat - Fallow fields, alluvial soils, roadsides, railroads.

Origin - Native to U.S.

Other info. - This species can be found throughout Missouri. The plant is low growing and easy to ID in the field because of its toothed leaves and pale yellow flowers. The flowers of this species open at night and close when hit by strong sunlight.
Although typically hairy as mentioned above, this species can sometimes be glabrate.

Photographs taken in Gainesville, FL., 6-19-02.