4. Oenothera rosea L' Her. ex Ait., Hort. Kew ed. 1. 2: 3. 1789; Clarke in Hook. f., Fl. Brit. Ind. 2: 582. 1879; Raven in Tutin et al., Fl. Eur. 2: 308. 1968; R. R. Stewart, Ann. Cat. Vasc. Pl. W. Pak. & Kashm. 508. 1972.
Peter C. Hoch and Peter H. Raven
Hartmannia rosea (L' HJr. ex Ait.) G. Don in Sweet, Hort. Brit. ed. 3. 236. 1839.
Well-branched perennial herb, flowering the first year, stems ascending, 1-4 dm tall, densely strigillose, rarely mixed with sparse villous hairs. Leaves subentire or sinuate-pinnatifid, elliptic or rarely narrowly ovate, 2-5 x 1-2.5 cm, the petiole 2-25 mm long. Flowers opening near sunrise; mature buds erect. Floral tube 4-8 mm long. Sepals 7-12 mm long; sepal tips 0.1-0.5 mm long. Petals rose to rose-purple, obovate, 4-12 mm long. Style 0.8-1.4 cm long; the stigma surrounded by the anthers at anthesis. Capsule clavate, 1.3-3 cm long, tapering to a sterile stipe-like portion 0.5-2 cm long, the ridge on each valve ± prominent, the valve narrowly winged. Seeds in several indistinct rows in each locule, oblong-obovoid to obovoid, 0.7-0.9 mm long, the surface finely granular, with a dark spot at each end. Self-compatible and self-pollinating. Gametic chromosome number, n = 7 (rings of 14 in meiotic metaphase I).
Type locality: Peru.
Distribution: Native from central and southern Texas, USA, throughout Mexico and Central America to El Salvador, and throughout South America; naturalized throughout the warmer regions of the world. Sandy to clay soils, along creeks or in low weedy places, l000-2000 m elev. According to Stewart (loc. cit. 508. 1972), O. rosea is an old introduction from Mexico, which has run wild in many areas of Pakistan. He lists the following additional localities for which I have not seen specimens: Hazara, Poonch, Kashmir, Jhelum Valley. Fl. Per.: Apr-Sep.
One collection of Oenothera rhombipetala Nutt. ex Torr. & A. Gray has been collected in Afghanistan, Mazar-i-Sharif, Koelz 13192 (NA), and perhaps it may also occur in Pakistan. This species is easily distinguished from the others by its dense terminal spikes 1-3 dm long of yellow flowers, the slender buds 2-4 mm in diameter, rhombic-obovate petals and arcuate-cylindric capsules 12-16 mm long and ca. 2.5 mm in diameter. Oenothera rhombipetala is native in the Great Plains of the United States.