Oenothera hexandra (Ortega) W. L. Wagner & Hoch, Syst. Bot Monogr. 83: 212. 2007.

Wagner, Warren L., Krakos, Kyra N. & Hoch, Peter C., 2013, Taxonomic changes in Oenothera sections Gaura and Calylophus (Onagraceae), PhytoKeys 28, pp. 61-72 : 68-69

6. Oenothera hexandra (Ortega) W. L. Wagner & Hoch, Syst. Bot Monogr. 83: 212. 2007.

Basionym.

Gaura hexandra Ortega, Hort. matr. dec. 14. 1797.

Type.

Based on living plants cultivated at the Royal Botanical Garden in Madrid from seeds sent by Sessé from Mexico [erroneously said to be from Cuba] (Holotype: not located).-Mexico. México. Comunidad Temascaltepec, 19 May 1936, G. B. Hin ton 7688 (Neotype, designated, by Wagner et al. 2007: 212: MO-1717467!; Isoneotypes: C, F, G, GH, LL, MICH, NY, US!).

Annual herb from a stout taproot, usually well-branched at the base and above, 15-100 cm tall, villous proximally, the leaves subglabrous to densely short-villous, and becoming subglabrous, strigillose, and/or glandular-puberulent distally. Leaves in a basal rosette and cauline; rosette leaves lyrate, gradually narrowed to the petiole, usually quickly deciduous; cauline leaves 1-9 × 0.1-0.8 cm, linear to very narrowly elliptic or narrowly lanceolate, margin sinuate-dentate to subentire, subsessile. Inflorescence strict to somewhat branched, 7-53 cm long, bracts 2-5 cm long, narrowly lanceolate to ovate. Flowers 3-merous, opening at sunset; floral tube 4.5-7.5 mm; sepals 3-10 mm; petals 4.5-7 mm; staminal filaments 3-6 mm, anthers 1-2 mm, pollen 90-100% fertile; style 9-14.5 mm. Capsule indehiscent, 4.5-8 × 2-4.5 mm, nut-like, hard, woody, not reflexed, the body ellipsoid or narrowly obovoid, broadly winged on the angles and deeply furrowed between the angles, narrowed at the base but not stipitate. Seeds 3, 1.75-3 mm, ovoid, usually flattened on one or several sides by crowding in the fruit, yellowish to reddish brown. Gametic chromosome number: n = 7. Self-compatible and highly autogamous.

Phenology and distribution.

Flowering from March to November. From Durango, Mexico south in the Sierra Madre Occidental to the Trans Mexican Volcanic Belt, where abundant, and in Chiapas, Mexico as well as Guatemala in grasslands, meadows or oak woodlands, or disturbed areas, in sandy soils; 1800-2430 m.