Oenothera acutissima |
Oenothera coloradensis |
|
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flaming Gorge evening primrose |
Colorado beeblossom |
|
Habit | 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. | Herbs monocarpic perennial, strigillose proximally, short-hirtellous and strigillose distally, leaves sometimes glabrate; from stout, fleshy taproot. |
Stems | (when present) ascending, (1–)several–10, densely leafy, 1–2 cm. |
1–few-branched from base, 50–80(–100) cm. |
Leaves | 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. |
in a basal rosette and cauline, basal 4–18 × 1.5–4 cm, blade very narrowly elliptic, lanceolate, or oblanceolate; cauline 5–13 × 1–4 cm, blade narrowly elliptic, narrowly lanceolate, or narrowly oblanceolate, margins subentire or repand-denticulate. |
Flowers | 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. |
4-merous, zygomorphic, opening at sunset; floral tube 8–12 mm; sepals 9.5–13 mm; petals white, fading pink, rhombic-obovate, 7–12 mm; filaments 6.5–9 mm, anthers 2.5–4 mm, pollen 90–100% fertile; style 19–25 mm, stigma exserted beyond anthers at anthesis. |
Capsules | 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. |
ellipsoid or ovoid, sharply 4-angled, with fairly deep furrows alternating with angles, 6–8.5 × 2–3 mm; sessile. |
Seeds | asymmetrically cuneiform, 2–2.5 mm. |
1–4, yellowish to light brown, 2–3 × 1 mm. |
2n | = 14. |
= 14. |
Oenothera acutissima |
Oenothera coloradensis |
|
Phenology | Flowering May–Jun. | Flowering Jul–Sep. |
Habitat | Restricted to sandy and gravelly, reddish, soil in seasonally wet sites, meadows, depressions, along arroyos, among rocks, in mixed conifer forests, sagebrush scrub. | In wet meadow vegetation of North and South Platte River watersheds on high plains, sloping floodplains, drainage basins in heavy soil. |
Elevation | 1800–2400(–2600) m. (5900–7900(–8500) ft.) | 1500–2000 m. (4900–6600 ft.) |
Distribution |
CO; UT |
CO; NE; WY |
Discussion | 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.) |
Oenothera coloradensis is currently known from fewer than two dozen populations from southern Laramie and Platte counties in Wyoming, northern Weld County, Colorado, formerly near Fort Collins, Larimer County, Colorado, and in western Kimball County, Nebraska. It is federally listed as a threatened species in the United States. The primary threats are agricultural use of habitat, herbicide spraying to control weed species, and livestock trampling and grazing (see W. L. Wagner et al. 2013). Recent study by K. N. Krakos (unpubl.) has determined this species to be self-compatible. P. H. Raven and D. P. Gregory (1972[1973]) described this species as glandular puberulent in inflorescence, which was repeated in the recent revised taxonomy (Wagner et al.); however, examination of specimens show that P. A. Munz (1965) was correct in describing the pubescence of the inflorescence as non-glandular. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 10. | FNA vol. 10. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | O. flava var. acutissima | Gaura coloradensis, G. neomexicana subsp. coloradensis, G. neomexicana var. coloradensis |
Name authority | W. L. Wagner: Syst. Bot. 6: 153, fig. 1. (1981) | (Rydberg) W. L. Wagner & Hoch: Syst. Bot. Monogr. 83: 211. (2007) |
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