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Howard's evening-primrose

Fendler evening primrose, Hartweg's sundrops

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 perennial, sometimes suffrutescent, strigillose, glandular puberulent, glabrous, hirtellous, or short-pilose; from a stout taproot.
Stems

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

1–many, erect to ascending, unbranched to densely branched, 4–60 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.

0.3–6.5 × 0.04–1.2 cm, sometimes fascicles of small leaves 0.1–1.5 cm present in non-flowering axils;

petiole 0–0.2 cm;

blade elliptic, lanceolate, linear, or filiform to ovate or oblanceolate, usually not much reduced distally, proximalmost leaves sometimes obovate to spatulate, base attenuate to obtuse, truncate, or subcordate, sometimes clasping, margins entire or serrate, often undulate, apex acute.

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.

usually 1 per stem opening per day in afternoon or near sunset;

buds with free tips 0.5–6 mm;

floral tube 16–50(–60) mm, funnelform in distal 1/2 or less;

sepals 7–28 mm;

petals yellow, fading pale pinkish or pale purple, 10–35 mm;

filaments 4–13 mm, anthers 5–13 mm, pollen 85–100% fertile;

style 25–65(–75) mm, stigma yellow, quadrangular, usually exserted beyond anthers.

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.

6–40 × 2–4 mm, hard, promptly dehiscent throughout their length.

Seeds

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

obovoid, 1–2.5 mm.

2n

= 28, 42, 56.

= 14, 28.

Oenothera howardii

Oenothera hartwegii

Phenology Flowering May–Jul.
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.
Elevation (1000–)1500–2300(–3000) m. ((3300–)4900–7500(–9800) ft.)
Distribution
from FNA
CO; KS; NV; UT; WY
[WildflowerSearch map]
[BONAP county map]
from USDA
c United States; sw United States; n Mexico
[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.)

Subspecies 5 (5 in the flora).

Oenothera hartwegii consists of five intergrading subspecies, which are generally locally common on rocky, sandy, gypsum, or limestone soil in arid to relatively mesic open areas, in southeastern Colorado, southwestern Kansas, western Oklahoma, Texas (except eastern part), New Mexico, southeastern and east-central Arizona, and in Mexico from Chihuahua, northern Coahuila, and northwestern Tamaulipas south to Aguascalientes. H. F. Towner (1977) found that O. hartwegii is self-incompatible and usually vespertine; two of the subspecies (filifolia and maccartii) open early in the afternoon and are pollinated both day and evening.

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

Key
1. Leaves (except proximalmost): blade base truncate or subcordate and clasping; plants densely pubescent with mixture of hair types, but always short-pilose and usually also hirtellous, sometimes also strigillose, especially on leaves, or glandular puberulent distally.
subsp. pubescens
1. Leaves: blade base attenuate or obtuse; plants glabrous, sparsely strigillose, or glandular puberulent.
→ 2
2. Plants usually glabrous throughout, sometimes glandular puberulent on distal parts, especially on ovary.
subsp. fendleri
2. Plants strigillose and/or glandular puberulent, especially on distal parts.
→ 3
3. Plants glandular puberulent throughout, more densely so on distal parts, sometimes also sparsely strigillose on ovary and leaves; leaf blades filiform to narrowly lanceolate.
subsp. filifolia
3. Plants usually strigillose, rarely glandular puberulent; leaf blade narrowly lanceolate to oblanceolate, sometimes linear.
→ 4
4. Leaf blades narrowly lanceolate, sometimes linear, margins entire or shallowly and sparsely serrulate, sometimes undulate; plants sparsely to densely strigillose throughout.
subsp. hartwegii
4. Leaf blades usually narrowly lanceolate to lanceolate or oblanceolate, rarely linear, margins subentire or serrulate, usually crinkled-undulate; plants usually sparsely strigillose, sometimes glandular puberulent.
subsp. maccartii
Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Megapterium Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Calylophus > subsect. Salpingia
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. 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. 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
Subordinate taxa
O. hartwegii subsp. fendleri, O. hartwegii subsp. filifolia, O. hartwegii subsp. hartwegii, O. hartwegii subsp. maccartii, O. hartwegii subsp. pubescens
Synonyms Lavauxiahowardii a. Calylophus hartwegii, Galpinsia hartwegii, Salpingia hartwegii
Name authority (A. Nelson) M. E. Jones ex Prain in B. D. Jackson et al.: Index Kew., suppl. 3: 121. (1908) — (as howardi) Bentham: Pl. Hartw., 5. (1839) — (as hartwegi)
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