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Photo is of parent taxon

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.
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.

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.

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.

2n

= 14.

Oenothera cespitosa subsp. cespitosa

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
Source FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Pachylophus > Oenothera cespitosa
Sibling taxa
O. cespitosa subsp. crinita, O. cespitosa subsp. macroglottis, O. cespitosa subsp. marginata, O. cespitosa subsp. navajoensis
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
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