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butte primrose, fragrant evening primrose, rock rose

Habit Herbs acaulescent or short-caulescent, glabrous or densely strigillose or hairs sometimes ± spreading, rarely sparsely glandular puberulent on flower parts. Herbs (annual or perennial), [shrubs].
Stems

(if present) usually unbranched, rarely with 1–several short laterals, 0–6(–21) cm.

Leaves

(2.8–)7–16(–21) × (0.3–)1–3(–5) cm;

petiole (1–)3–7(–10) cm;

blade obovate to linear-oblanceolate, margins coarsely and irregularly serrate or dentate, sometimes pinnately lobed or subentire.

alternate or basal;

stipules absent.

Flowers

floral tube (20–)40–60(–85) mm;

sepals (15–)24–35(–40) mm;

petals fading rose pink to dark rose purple, (16–)25–40(–48) mm;

filaments (12–)15–24(–26) mm, anthers 9–12 mm;

style (45–)60–120 mm.

usually actinomorphic, rarely slightly zygomorphic (in Oenothera), (3 or)4-merous;

stamens 2 times as many, or rarely as many, as sepals;

pollen usually shed in monads, rarely tetrads (Chylismia sect. Lignothera).

Fruit

a dry capsule, usually dehiscent, sometimes indehiscent.

Capsules

falcate or sigmoid, becoming nearly straight at maturity, asymmetrical and often somewhat flattened, lanceoloid to ovoid, (10–)20–40(–50) × 4–6 mm, valve margins with prominent, sinuate ridge with 5–10 peaks, or nearly distinct tubercles;

pedicel 0.5–3 mm.

Seeds

narrowly obovoid, 2.5–3.9 × 1.2–1.7 mm embryo 1/2–2/3 of seed volume, surface papillose;

seed collar oblong, membrane depressed deeply into raphial cavity, margin usually sinuate only distally, sometimes sinuate throughout.

few to numerous, without hairs or wings, [very rarely with asymmetrical dry wing (Xylonagra)], or with dry (Oenothera), erose or smooth wing, or with thick, papillate wings (Chylismiella).

2n

= 14.

Oenothera cespitosa subsp. cespitosa

Onagraceae tribe Onagreae

Phenology Flowering May–Jul(–Aug).
Habitat Scattered or forming colonies in open sites, loose to hard, compacted clay, sandy soil, rocky slopes of shale, volcanic, or fine sandstone, gumbo flats, badlands, bluffs, exposed rocky ridges, roadcuts, grasslands, sagebrush, shadscale scrub, exposed sites in montane conifer forests.
Elevation 800–3100 m. (2600–10200 ft.)
Distribution
from FNA
CO; ID; MT; ND; NE; NV; OR; SD; UT; WA; WY; AB; MB; SK
North America; Mexico; Central America; South America; West Indies
Discussion

Genera 13, species 265 (12 genera, 199 species in the flora).

Onagreae account for more than half the total genera in Onagraceae and diversified from a center in southwestern North America (L. Katinas et al. 2004). Delimitation of the tribe by W. L. Wagner et al. (2007) differs from previous ones by the exclusion of Gongylocarpus, now in its own tribe, by the segregation of eight genera (Camissoniopsis, Chylismia, Chylismiella, Eremothera, Eulobus, Neoholmgrenia, Taraxia, and Tetrapteron) from Camissonia, and by the inclusion of three previously separate genera (Calylophus, Gaura, and Stenosiphon) in Oenothera. Within the branch of the family that lacks stipules (Gongylocarpeae, Epilobieae, and Onagreae), the last two tribes form a clade that has very strong molecular support (R. A. Levin et al. 2003, 2004), but no obvious morphological synapomorphy. The clade may be defined by a cytogenetic change from the base chromosome number of x = 11 found in Circaeeae, Gongylocarpeae, and Lopezieae, to x = 18 in Epilobieae, and x = 7 in Onagreae; however, these changes could also have occurred independently. Other than the new chromosome number x = 7, the only apparent morphological synapomorphy for Onagreae alone is pollen with prominent apertural protrusions (J. Praglowski et al. 1987, 1989), a character state also found in Circaeeae (Praglowski et al. 1994). The monophyly of Onagreae has moderate (Levin et al. 2004) to strong support (V. S. Ford and L. D. Gottlieb 2007).

(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. Pachylophus > Oenothera cespitosa Onagraceae > subfam. Onagroideae
Sibling taxa
O. cespitosa subsp. crinita, O. cespitosa subsp. macroglottis, O. cespitosa subsp. marginata, O. cespitosa subsp. navajoensis
Subordinate taxa
Synonyms O. cespitosa subsp. montana, O. cespitosa var. montana, O. cespitosa subsp. purpurea, O. cespitosa var. purpurea, O. marginata var. purpurea, O. montana, O. scapigera, Pachylophus canescens, P. glaber, P. montanus
Name authority unknown Dumortier: Fl. Belg., 89. (1827)
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