Oenothera cordata |
Oenothera hartwegii |
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heartleaf evening primrose |
Fendler evening primrose, Hartweg's sundrops |
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Habit | Herbs annual or biennial, densely to sparsely strigillose, glandular puberulent or sometimes also sparsely villous distally. | Herbs perennial, sometimes suffrutescent, strigillose, glandular puberulent, glabrous, hirtellous, or short-pilose; from a stout taproot. | ||||||||||||||||
Stems | unbranched or branched primarily distally, 25–70 cm. |
1–many, erect to ascending, unbranched to densely branched, 4–60 cm. |
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Leaves | in a basal rosette and cauline, basal 6–12 × 0.7–2 cm, cauline 2–10 ×0.5–3 cm; subsessile; blade narrowly elliptic to oblanceolate, gradually narrowly lanceolate to lanceolate, elliptic, or ovate distally, margins lobed to remotely dentate or subentire; bracts shorter than capsule they subtend, 0.5–1.7 cm. |
0.3–6.5 × 0.04–1.2 cm, sometimes fascicles of small leaves 0.1–1.5 cm present in non-flowering axils; petiole 0–0.2 cm; blade elliptic, lanceolate, linear, or filiform to ovate or oblanceolate, usually not much reduced distally, proximalmost leaves sometimes obovate to spatulate, base attenuate to obtuse, truncate, or subcordate, sometimes clasping, margins entire or serrate, often undulate, apex acute. |
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Inflorescences | open, lax, usually unbranched, mature buds usually overtopping spike apex. |
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Flowers | 1–few per spike opening per day near sunset; buds erect, with free tips erect, 1–3 mm; floral tube nearly straight, 20–40 mm; sepals 15–25 mm; petals yellow, broadly elliptic to rhombic-ovate, 20–30 mm; filaments 17–22 mm, anthers 4–7 mm, pollen 85–100% fertile; style 50–65 mm, stigma usually exserted beyond anthers at anthesis. |
usually 1 per stem opening per day in afternoon or near sunset; buds with free tips 0.5–6 mm; floral tube 16–50(–60) mm, funnelform in distal 1/2 or less; sepals 7–28 mm; petals yellow, fading pale pinkish or pale purple, 10–35 mm; filaments 4–13 mm, anthers 5–13 mm, pollen 85–100% fertile; style 25–65(–75) mm, stigma yellow, quadrangular, usually exserted beyond anthers. |
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Capsules | narrowly lanceoloid, 15–33 × 2–3 mm. |
6–40 × 2–4 mm, hard, promptly dehiscent throughout their length. |
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Seeds | dark brown, ellipsoid, 1–1.4 ×0.4–0.6 mm. |
obovoid, 1–2.5 mm. |
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2n | = 14. |
= 14, 28. |
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Oenothera cordata |
Oenothera hartwegii |
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Phenology | Flowering Apr–Jul. | |||||||||||||||||
Habitat | Sandy, open places in oak woodlands. | |||||||||||||||||
Elevation | 30–200 m. (100–700 ft.) | |||||||||||||||||
Distribution |
TX |
c United States; sw United States; n Mexico
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Discussion | Oenothera cordata is self-incompatible. It occurs in a narrow range in eastern Texas (Austin, Bastrop, Colorado, Fayette, Guadalupe, Goliad, Matagorda, San Patricio, Victoria, Waller, and Wilson). It apparently occasionally hybridizes with O. heterophylla subsp. heterophylla where their ranges come together. Oenothera bifrons D. Don 1838 (not Lindley 1831) pertains here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies 5 (5 in the flora). Oenothera hartwegii consists of five intergrading subspecies, which are generally locally common on rocky, sandy, gypsum, or limestone soil in arid to relatively mesic open areas, in southeastern Colorado, southwestern Kansas, western Oklahoma, Texas (except eastern part), New Mexico, southeastern and east-central Arizona, and in Mexico from Chihuahua, northern Coahuila, and northwestern Tamaulipas south to Aguascalientes. H. F. Towner (1977) found that O. hartwegii is self-incompatible and usually vespertine; two of the subspecies (filifolia and maccartii) open early in the afternoon and are pollinated both day and evening. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||||||||||||||
Parent taxa | ||||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | Calylophus hartwegii, Galpinsia hartwegii, Salpingia hartwegii | |||||||||||||||||
Name authority | J. W. Loudon: Ladies’ Flower-gard. Ornam. Perenn. 1: 167. (1843) | Bentham: Pl. Hartw., 5. (1839) — (as hartwegi) | ||||||||||||||||
Web links |