Oenothera linifolia |
Oenothera acutissima |
|
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threadleaf evening-primrose, threadleaf sundrop |
flaming Gorge evening primrose |
|
Habit | Herbs annual, caulescent, strigillose or glabrous, also often glandular puberulent, especially distally; from a sparsely branched taproot. | Herbs perennial, subacaulescent or very short-caulescent, strigillose mostly along leaf margins and flower parts, also sparsely glandular puberulent, sometimes also sparsely hirsute distally; from a stout taproot, usually with several long, lateral roots often producing adventitious shoots. |
Stems | unbranched or with many ascending branches arising near base, erect, 10–50 cm. |
(when present) ascending, (1–)several–10, densely leafy, 1–2 cm. |
Leaves | 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. |
primarily in a basal rosette, 7–14(–18) × (0.3–)0.5–1(–1.5) cm, moderately thick and stiff; petiole (1.2–)3–5 cm; blade linear to very narrowly elliptic, margins irregularly and coarsely dentate or pinnately lobed, apex long-attenuate. |
Flowers | 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. |
1–3 opening per day near sunset; buds with unequal free tips 1–3 mm; floral tube (53–)60–100 mm; sepals 26–50 mm; petals bright yellow, fading deep reddish orange, drying purplish brown, 28–50 mm; filaments 21–35 mm, anthers 9–11 mm; style 75–143 mm, stigma exserted beyond anthers. |
Capsules | 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. |
leathery in age, oblong-oblanceoloid, narrowly winged, wings oblong, 1–2(–4) mm wide, broadest near apex, 14–18(–22) × 7–8 mm (excluding wings), apex abruptly constricted, dehiscent 1/4–1/3 their length, valve surface with inconspicuous veins; sessile. |
Seeds | clustered in each locule, ovoid, surface minutely papillose, 1 × 0.5 mm. |
asymmetrically cuneiform, 2–2.5 mm. |
2n | = 14. |
= 14. |
Oenothera linifolia |
Oenothera acutissima |
|
Phenology | Flowering Apr–Jun(–Aug). | Flowering May–Jun. |
Habitat | Prairies, open woodlands, open rocky and sandy sites, roadsides. | Restricted to sandy and gravelly, reddish, soil in seasonally wet sites, meadows, depressions, along arroyos, among rocks, in mixed conifer forests, sagebrush scrub. |
Elevation | 0–400 m. (0–1300 ft.) | 1800–2400(–2600) m. (5900–7900(–8500) ft.) |
Distribution |
AL; AR; FL; GA; IL; KS; KY; LA; MO; MS; NC; OK; SC; TN; TX
|
CO; UT |
Discussion | Kneiffia linearifolia Spach (1835) is an illegitimate name based on Oenothera linifolia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Oenothera acutissima is known only from the vicinity of Manila, eastern Uinta Mountains, Daggett and Duchesne counties, Utah, east to areas in and near the foothills of the Douglas and Blue mountains, in Uinta County, Utah, and Moffat County, Colorado. (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. Peniophyllum | Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Lavauxia > subsect. Lavauxia |
Sibling taxa | ||
Synonyms | Kneiffia linifolia, O. linifolia var. glandulosa, Peniophyllum linifolium | O. flava var. acutissima |
Name authority | Nuttall: J. Acad. Nat. Sci. Philadelphia 2: 120. (1821) | W. L. Wagner: Syst. Bot. 6: 153, fig. 1. (1981) |
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