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Howard's evening-primrose

Engelmann's evening-primrose

Habit Herbs acaulescent or sometimes caulescent, moderately to densely strigillose and glandular puberulent, sometimes also sparsely to moderately hirsute; from a taproot, sometimes lateral roots producing adventitious shoots. Herbs winter-annual, conspicuously villous throughout, also strigillose on leaves and distal parts; from a taproot.
Stems

(when present) ascending, longer ones becoming decumbent, leafy, sometimes densely so, 0–10(–30) cm.

erect, unbranched or with few, spreading branches, 30–50(–80) cm.

Leaves

in a basal rosette, sometimes also cauline, (6–)8.5–17(–23) × (0.5–)1–2(–3) cm;

petiole 2–7.5 cm;

blade usually oblanceolate, elliptic to narrowly oblong, rarely lanceolate, margins often undulate, entire or remotely and irregularly pinnately lobed mostly in proximal 1/2, rarely more regularly pinnately lobed and lobing extending to distal 1/2, sinuses usually extending less than 1/2 to midrib, lobes triangular to oblong or linear, (1–)4–9(–13) mm, apex acute to obtuse.

in a basal rosette and cauline, rosette weakly developed or absent, at least during flowering, (1–)2–6(–8) × 1–2(–3) cm;

sessile;

blade lanceolate to oblong lanceolate, proximal ones sometimes oblanceolate, margins coarsely repand-dentate or -pinnatifid.

Flowers

usually 1 or 2, rarely more, opening per day near sunset, strongly and sweetly scented;

buds with unequal free tips 1–3(–4) mm;

floral tube (43–)60–110(–125) mm;

sepals (30–)35–60(–80) mm;

petals brilliant yellow, fading deep red, drying deep reddish purple to reddish brown, usually broadly obovate, rarely subrhombic, (30–)40–60(–73) mm, sometimes with a terminal tooth;

filaments (19–)25–38 mm, anthers 10–17 mm;

style(90–)110–145(–165) mm, stigma exserted beyond anthers at anthesis.

1–several opening per day near sunset;

buds nodding, weakly quadrangular, without free tips;

floral tube 20–30 mm;

sepals 13–21 mm, not spotted or with scattered small, maroon spots;

petals white, fading pink, broadly obovate or obcordate, 15–30 mm;

filaments 14–16 mm, anthers 6–8 mm;

style 40–50 mm, stigma exserted beyond anthers at anthesis.

Capsules

leathery, ovoid, narrowly ovoid, or narrowly lanceoloid to broadly ellipsoid, winged, wings (2–)4–7(–11) mm wide, body (20–)25–50(–80) × 4–6 mm, dehiscent 1/4–1/3 their length;

pedicel 2–6 mm.

widely spreading, woody in age, straight or slightly curved, cylindrical, obtusely 4-angled, especially toward base, tapering gradually from base to apex, 30–60 × 2–3 mm;

sessile.

Seeds

numerous, usually in 1 row per locule, rarely in 2 rows toward base, obovoid to subcuboid, 3–8 × 2.5–3.5 mm.

numerous, in 1 row per locule, brown, narrowly obovoid, 1–1.5 mm.

2n

= 28, 42, 56.

= 14.

Oenothera howardii

Oenothera engelmannii

Phenology Flowering May–Jul. Flowering Apr–Aug(–Sep).
Habitat Open or rocky areas, in shale, fine-textured sandstones, clays, gypsum, or limestone from High Plains grasslands, open sites in pinyon-juniper woodlands, ponderosa pine-Douglas fir forests. Sandy prairies, dunes, disturbed areas, roadsides.
Elevation (1000–)1500–2300(–3000) m. ((3300–)4900–7500(–9800) ft.) 500–1300 m. (1600–4300 ft.)
Distribution
from FNA
CO; KS; NV; UT; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; KS; NM; OK; TX
[WildflowerSearch map]
[BONAP county map]
Discussion

Oenotherahowardii is known from three disjunct areas: three collections on the High Plains (Baca and Otero counties, Colorado, and Hamilton County, Kansas); open yucca-juniper grassland, rocky slopes or disturbed areas on shale substrates along the Colorado counties of Boulder, Denver, Jefferson, and Larimer, and just over the state line in Wyoming; and, common to scattered, mostly on rocky slopes but also in shaded canyon sites on fine-textured red sandstones, clays, gypsum, chalky white degraded limestone or limestone in pinyon-juniper woodland to ponderosa pine-Douglas fir forest in southern Utah and eastern Nevada.

A. Nelson intended to publish Lavauxia howardii as a new combination and base it on Oenothera howardii M. E. Jones (1893), which was not validly published at the time, but inadvertently published L. howardii as a new species. Oenothera howardii (A. Nelson) W. L. Wagner is an isonym.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Oenothera engelmannii is self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010). It has a relatively narrow distribution in sandy areas of eastern New Mexico and western Texas, extending to southeastern Colorado, western Oklahoma, and southwestern Kansas. The flower size seems to vary, with larger flowers in eastern New Mexico and considerably smaller flowers in the eastern part of its range.

(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. Megapterium Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra
Sibling taxa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. elata, O. engelmannii, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. primiveris, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. elata, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. howardii, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. primiveris, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
Synonyms Lavauxiahowardii a. Anogra pallida var. engelmannii, A. engelmannii
Name authority (A. Nelson) M. E. Jones ex Prain in B. D. Jackson et al.: Index Kew., suppl. 3: 121. (1908) — (as howardi) (Small) Munz: Amer. J. Bot. 18: 316. (1931) — (as engelmanni)
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