Flower:

Flowers are single in the mid and upper leaf axils along branching stems, about 1 inch across with 4 yellow heart-shaped petals and 8 yellow stamens surrounding a style with a cross-shaped stigma in the center. The stamens and style are typically shorter than the petals.

The 4 sepals behind the flower are up to ~½ inch (5 to 15 mm) long and bend back away from the flower as it develops, pairs typically connected along one edge (connivent) until the flower opens, are yellowish-green and variously hairy, sometimes with glandular hairs. The floral tube, connecting the ovary nestled in the leaf axil and base of the flower, is ½ to 1 3/8 inches (12 to 35 mm) long and resembles a flower stalk. The flowers open in the evening and close up during the heat of the day.

Leaves and stems:

Leaves are basal and alternate, elliptic to oblong to somewhat spatula-shaped in outline, the basal and lower stem leaves up to 6 inches (4 to 15 cm) long, up to about 1 3/8 inch (1 to 3.5 cm) wide, short-stalked, becoming smaller and stalkless as they ascend the stem. Edges are shallowly to deeply lobed, sometimes lobed at the base and more toothed at the tip. The upper surface is hairless to sparsely hairy, the lower more densely hairy. Stems are single, unbranched to many-branched, erect to ascending to sprawling, and variously hairy.

Fruit:

Fruit is a slender, tubular capsule nestled in the leaf axil, ¾ to 2 inches (2 to 5 cm) long, straight to slightly curved, with four small conspicuously flared lobes at the tip.

Inside are many light brown seeds, .9 to 1.8 mm long, pitted all across the surface.

Notes:

There are currently only two herbarium records of Cut-leaved Evening Primrose in Minnesota, the first in 1945, the second in 1991, and both on sandy dunes in the northern Twin Cities metro area, though it was more recently spotted in a nursery production field in Sherburne County. The DNR considers it native to the state even though our two historical populations seem a bit disjunct from the next closest neighbors in Wisconsin and those populations have not persisted; it is not listed as rare but the DNR does track it. A native annual or short-lived perennial that spreads by reseeding, it is considered something of a weedy species in parts of its range and an agricultural pest in parts of California. Traveling through the southern US we spotted it on weedy roadsides in several states. While the flowers resemble those of other Evening Primrose species, the lobed leaves and somewhat ragged growth habit separate it from the rest.