Oenothera sect. Paradoxus

Herbs perennial, caulescent; from a taproot, lateral roots producing adventitious shoots. Stems weakly erect becoming decumbent, branched or unbranched. Leaves in a basal rosette and cauline, 1–5 cm; blade margins pinnately lobed to sinuate-toothed or dentate. Inflores­cences solitary flowers in axils of distal leaves. Flowers opening near sunset; buds erect, terete, with free tips coherent; floral tube (37–)45–60(–65) mm; sepals splitting along one suture, reflexed as a unit to one side; petals lemon-yellow, fading orange-red to reddish purple, usually elliptic, sometimes oblanceolate; stigma deeply divided into 4 linear lobes. Capsules hard and woody, narrowly ovoid to ovoid, 4-angled, apex tapering to a short, sterile beak, valves with prominent midrib and capsule appearing 8-ribbed, tardily dehiscent 1/3 their length; sessile. Seeds numerous, in 1 or 2 partially overlapping rows per locule, asymmetrically cuneiform to rhombic, irregularly angled, surface minutely beaded. 2n = 14, 28.

Distribution

sw, sc United States, n Mexico.

Discussion

Species 1.

Section Paradoxus consists of a single species, restricted to the Chihuahuan Desert.

Selected References

None.

Lower Taxa

Oenothera havardii