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Oenothera acaulis

Distribution: Occurring in usually small scattered populations in damp or seasonally wet sites in grassy areas, rocky slopes, old fields, stabilized dunes, and roadsides from Estancia Talinay and La Cebeda in Region Coquimbo, Chile, south to Panquipulli, Region Los Lagos, and from the coast into the western slope of the Andes, sea level to ca. 2600 m.

Habit: Acaulescent or caulescent perennial herb from a stout taproot, the caudex usually several- to many-branched forming a clump, stems green or flushed with red, 0-50(-70) cm long, decumbent, densely to sparsely hirtellous and glandular pubescent also usually mixed with moderate to dense amounts of short-villous hairs, rarely strigillose rather than short-villous, sometimes exclusively short-villous or nearly so.

Leaves: Leaves green, midrid prominent, short-villous and hirtellous, more densely so or confined to the margins and major veins, sometimes exclusively one hair type or the other and then usually more evenly distributed over the surface, also often glandular pubescent, usually more densely so along the margins, narrowly oblanceolate to oblanceolate, (4-)6-15(-23) cm long, (0.6-)1.5-6 cm wide, irregularly pinnatifid into linear or rarely lanceolate lobes, usually with a large terminal lanceolate, elliptic to narrowly oblong lobe, the margins of the lobes subentire to irregulary dentate, apex of lobes acute, tapering to a petiole (0.5-)1.5-6 cm long.

Flowers: Buds with unequal free tips 1-3(-5) mm long. Flowers 1-3 per rosette or stem per day, opening near sunset. Ovary moderately to densely hirtellous, short-villous and often also glandular pubescent or sometimes the hirtellous or short-villous predominant, (6-)10-16 mm long, sessile, floral tube (3.5-)6-15(-17.5) cm long, 0.5-2 mm in diameter medially, flaring to (3-)4-6(-7) mm at the mouth, pubescence same as ovary although usually less dense, sepals green or tinged with red, (1.2-)1.5-3.8 cm long, 2-5 mm wide, pubescence the same as the floral tube and ovary, petals white, fading pink, drying purple, broadly obcordate or obovate, (1.2-)2-5.3 cm long, (1.3-)2.2-5.6 cm wide. Staminal filaments white, 10-20 mm long. Anthers pale yellow, (4-)8-14 mm long, pollen 20%-100% fertile, style whitish, (4.5-)7.3-17(-19.5) cm long, stigma lobes 3-9 mm long, usually elevated above anthers, but sometimes surrounded by them.

Fruit: Capsule narrowly obovoid to clavate or ellipsoid, (10-)13-20(-30) mm long, 5-12 mm in diameter, becoming hard and woody in age, the surface conspicuously wrinkled, constricted to a short beak, the free tips spreading 1-3 mm long, the valves with a triangular wing 2.5-7 mm wide, usually confined to the upper 1/3 of the capsule, rarely extending slightly further, abruptly truncated and absent or nearly so from the lower half, dehiscing to the middle of the wings or slightly less, 1/4-1/3 the length of the capsule.

Seeds: Seeds ca. 40-150 per capsule in two partially overlapping rows or one irregular row, sometimes many of the seeds appear shrivelled and aborted, slightly asymmetrically cuneiform, curved or straight, brown to a dark purplish brown sometimes mottled with lighter areas, 2.5-3.5 mm long, 1.1-2.2 mm wide, 0.7-1.1 mm high, the surface minutely beaded, with a thickish wish at the distal end, the wing extending narrowly along both adaxial margins forming a concave adaxial surface, often the wing slightly larger along one of the margins, the raphe slightly raised.

Chromosomes: Gametic chromosome number, n=7 (ring of 14 chromosomes at meiotic metaphase I, two smaller rings of 6 and 8, ring of 12 and one bivalent, or ring of 4 and 5 bivalents).

Notes: Flowering from September to January,sometimes as late as March. Self-compatible and apparently outcrossing to autogamous, but even the flowers with elevated stigmas selfing as the flowers fade.


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