Oenothera mexicana |
Oenothera nutans |
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Mexican evening primrose |
nodding evening-primrose |
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Habit | Herbs annual, moderately to sparsely strigillose and densely long-villous, sometimes also becoming glandular puberulent distally. | Herbs biennial, often appearing glabrous to naked eye, usually strigillose and sparsely to moderately villous proximal to inflorescence, hairs translucent and with or without pustules, pustules not red (in fresh material), inflorescence glabrous, glandular puberulent, or strigillose and glandular puberulent. |
Stems | erect to ascending, usually unbranched, or with arcuate lateral branches arising from rosette, 15–40(–60) cm. |
erect, red on proximal parts, green on distal ones, rarely red throughout, unbranched or with branches obliquely arising from rosette and secondary branches arising from main stem, 30–200 cm. |
Leaves | in a basal rosette and cauline, basal 6–10 × 1–2.5 cm, cauline 3–7.5 × 0.8–2 cm; blade usually grayish green, narrowly oblanceolate to narrowly oblanceolate, margins deeply lobed, lobes usually dentate; bracts distalmost erect, revolute. |
in a basal rosette and cauline, basal 10–32 × 3–7 cm, cauline 6–20 × 2–8 cm; blade green to pale green, narrowly oblanceolate to narrowly obovate, or narrowly elliptic, sometimes lanceolate distally, margins usually flat, rarely undulate, bluntly dentate, teeth widely spaced, sometimes sinuate-dentate proximally; bracts caducous. |
Inflorescences | erect, unbranched or with secondary branches just proximal to main one. |
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Flowers | usually 1 opening per day near sunset; buds erect, with free tips erect or appressed, 0.5–2.5 mm; floral tube 23–28 mm; sepals 5–12 mm; petals yellow, fading orange, broadly obovate or shallowly obcordate, 6–15 mm; filaments 4–12 mm, anthers 3–4 mm, pollen 85–100% fertile; style 27–40 mm, stigma surrounded by anthers at anthesis. |
opening near sunset; buds erect, 4–6 mm diam., with free tips terminal, erect, 1.5–6 mm; floral tube 30–43 mm; sepals yellowish green or flushed with red, 10–23 mm; petals yellow to pale yellow, fading pale yellowish white, very broadly obcordate, 14–25(–30) mm; filaments 10–25 mm, anthers 4–10 mm, pollen ca. 50% fertile; style 35–63 mm, stigma surrounded by anthers at anthesis. |
Capsules | cylindrical, sometimes slightly enlarged toward apex, 25–45 × 2.5–3 mm. |
erect or slightly spreading, dull green when dry, narrowly lanceoloid to narrowly ovoid, 12–36 × 3–6 mm, free tips of valves 1–1.5 mm. |
Seeds | ellipsoid to subglobose, 0.8–1.2 × 0.3–0.5 mm. |
1–1.9 × 0.6–0.9 mm. |
2n | = 14. |
= 14. |
Oenothera mexicana |
Oenothera nutans |
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Phenology | Flowering Apr–May. | Flowering Jun–Aug(–Sep). |
Habitat | Open, sandy sites. | Open, often disturbed sites, stream beds, flood plains, slopes, margins of mixed deciduous forests, roadsides, old fields. |
Elevation | 30–200 m. (100–700 ft.) | (200–)400–1700 m. ((700–)1300–5600 ft.) |
Distribution |
TX |
AL; AR; CT; DE; FL; GA; IN; KY; MA; MD; ME; MI; MO; NC; NH; NJ; NY; OH; PA; SC; TN; VA; VT; WV; ON |
Discussion | Oenothera mexicana is known only from southeastern Texas (Atascosa, Aransas, Bexar, Brooks, Burleson, De Witt, Frio, Gonzales, Kenedy, Medina, Newton, Refugio, San Patricio, Waller, and Washington counties). It is self-compatible and autogamous, but not a PTH species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Oenothera nutans is a PTH species and forms a ring of 14 chromosomes or a ring of 12 and 1 bivalent in meiosis, and is self-compatible and autogamous (W. Dietrich et al. 1997). It has plastome III and a BB genome composition. The disjunct occurrences of O. nutans in Arkansas and Missouri probably represent unintentional introductions by humans. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | O. laciniata var. mexicana, O. sinuata var. hirsuta, Raimannia mexicana | O. austromontana, O. biennis subsp. austromontana, O. biennis var. austromontana, O. biennis var. nutans |
Name authority | Spach: Nouv. Ann. Mus. Hist. Nat. 4: 347. (1836) | G. F. Atkinson & Bartlett: Rhodora 15: 83. (1913) |
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