Oenothera humifusa |
Oenothera linifolia |
|
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seabeach evening-primrose |
threadleaf evening-primrose, threadleaf sundrop |
|
Habit | Herbs annual or short-lived perennial, densely strigillose, sometimes also villous, also becoming glandular puberulent distally. | Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. |
Stems | erect to decumbent, much branched, 10–50(–90) cm. |
unbranched or with many ascending branches arising near base, erect, 10–50 cm. |
Leaves | in a basal rosette and cauline, basal 4–8 × 0.7–1 cm, cauline 1–7 × 0.3–1.5 cm; blade usually grayish green, narrowly oblong to narrowly elliptic or narrowly obovate, margins remotely shallowly dentate to subentire; bracts spreading, flat. |
in a basal rosette and cauline, basal 1–2(–4) × 0.2–0.6 cm, petiole 0.2–1(–1.5) cm, blade ovate to obovate or narrowly elliptic; cauline 1–4 × less than 0.1 cm, sessile, blade linear or filiform. |
Flowers | usually 1 opening per day near sunset; buds erect, with free tips erect and appressed or slightly spreading, 0.5–2 mm; floral tube 15–35 mm; sepals3–11 mm; petals yellow, very broadly obovate or obcordate, 4.5–16 mm; filaments 4–11 mm, anthers 2–5.5 mm, pollen ca. 50% fertile; style 23–45 mm, stigma surrounded by anthers at anthesis. |
usually 1–3 opening per day near sunrise; buds without free tips; sepals 1.5–2 mm; petals bright yellow, fading pink, obcordate to obovate, 3–5(–7) mm; filaments 1–2 mm, anthers 0.5–1 mm; style 1–2 mm, stigma surrounded by anthers at anthesis. |
Capsules | cylindrical, sometimes slightly enlarged toward apex, 15–45 × 2–3 mm. |
ellipsoid-rhombic to subglobose, 4-angled, 4–6(–10) × 1.5–3 mm, stipe 0–4 mm, valve midrib raised at distal end, indehiscent or tardily dehiscent distally; sessile. |
Seeds | usually ellipsoid to broadly ellipsoid, rarely subglobose, 1–2 × 0.5–0.9 mm. |
clustered in each locule, ovoid, surface minutely papillose, 1 × 0.5 mm. |
2n | = 14. |
= 14. |
Oenothera humifusa |
Oenothera linifolia |
|
Phenology | Flowering Apr–Nov. | Flowering Apr–Jun(–Aug). |
Habitat | Dunes, open sandy places along or near Atlantic coast. | Prairies, open woodlands, open rocky and sandy sites, roadsides. |
Elevation | 0–10 m. (0–0 ft.) | 0–400 m. (0–1300 ft.) |
Distribution |
AL; DE; FL; GA; LA; MD; MS; NC; NJ; PA; SC; VA; Dunes; open sandy places along or near Atlantic coast; West Indies (Cuba); Bermuda
|
AL; AR; FL; GA; IL; KS; KY; LA; MO; MS; NC; OK; SC; TN; TX
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Discussion | Oenothera humifusa is a PTH species and forms a ring of 14 chromosomes in meiosis, and is self-compatible and autogamous (W. Dietrich and W. L. Wagner 1988). The inland collection from Iredell County, North Carolina, presumably represents an introduction. There are two geographically separated morphological forms of O. humifusa. Plants of one form are somewhat decumbent, with subentire cauline leaves and bracts; this form occurs in the southern part of the range. The other form is more upright, with more deeply divided leaves; it occurs from North Carolina northward. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Kneiffia linearifolia Spach (1835) is an illegitimate name based on Oenothera linifolia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Oenothera > subsect. Raimannia | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Peniophyllum |
Sibling taxa | ||
Synonyms | O. niveifolia, O. sinuata var. humifusa, Raimannia humifusa | Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium |
Name authority | Nuttall: Gen. N. Amer. Pl. 1: 245. (1818) | Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) |
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