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fourpoint evening primrose

shortfruit evening-primrose

Habit Herbs biennial, densely to sparsely strigillose, sometimes also sparsely glandular puberulent distally. Herbs acaulescent or sometimes caulescent, strigillose, also hirsute, hairs often with reddish purple pustulate base, glandular puberulent distally; from a woody taproot, sometimes lateral roots producing adventitious shoots.
Stems

sometimes with lateral branches arising obliquely from rosette, 30–100(–150) cm.

(when present) ascending, longer ones becoming decumbent, usually densely leafy, 0–20(–36) cm.

Leaves

in a basal rosette and cauline, basal 6–20 × 0.6–2 cm, cauline 3–15 × 0.8–2.5 cm;

blade narrowly oblanceolate, gradually narrowly elliptic to narrowly lanceolate, oblanceolate, or ovate distally, margins lobed to remotely dentate or subentire;

bracts slightly longer than capsule they subtend.

in a basal rosette, sometimes also cauline, (3.1–)5–21(–34) × (0.3–)1.5–3.5(–5.3) cm;

petiole (0.8–)2.5–11(–15) cm;

blade usually lanceolate to elliptic, rhombic-obovate, sometimes suborbicular or linear, usually irregularly pinnatifid, some sinuses extending nearly to midrib, usually with a large terminal lobe (0.1–)1.5–2(–2.4) cm, margins erose, apex acute to obtuse or rounded.

Inflorescences

dense, usually without lateral branches, mature buds usually not overtopping spike apex.

Flowers

2–several per spike opening per day near sunset;

buds erect, with free tips erect, 0.5–3 mm;

floral tube slightly curved upward to ± straight, 30–45 mm;

sepals 15–30 mm;

petals yellow, broadly elliptic to rhombic-elliptic, 15–35 mm;

filaments 13–25 mm, anthers 3–8 mm, pollen 85–100% fertile;

style 25–50 mm, stigma exserted beyond anthers at anthesis.

usually 1–3, rarely more, opening per day near sunset, weakly scented;

buds with unequal free tips 1–7 mm;

floral tube (90–)120–210(–220) mm;

sepals 38–55 mm;

petals pale yellow to yellow, fading pale orange to pink, drying lavender to purple, usually broadly rhombic-obovate, sometimes obovate, (38–)45–58(–62) mm, distal margin usually erose;

filaments (16–)20–32 mm, anthers (8–)13–21 mm;

style (123–)155–240(–255) mm, stigma exserted beyond anthers at anthesis.

Capsules

narrowly lanceoloid, 13–25 × 2.5–3 mm.

leathery or corky, ovoid to narrowly ellipsoid, ± winged, wings 0–3(–5) mm wide, sometimes capsule with corky thickening between wings, then capsule only 4-angled, body (12–)18–40 × 6–10 mm, dehiscent 1/4 their length;

pedicel 0–3 mm.

Seeds

brown, sometimes flecked with dark red spots, ellipsoid, 1–1.7 × 0.4–0.7 mm.

usually numerous, in 1 or 2 rows per locule, obovoid to subcuboid, 3–5 × 1.8–2.2 mm.

2n

= 14.

= 14.

Oenothera rhombipetala

Oenothera brachycarpa

Phenology Flowering May–Oct. Flowering Mar–Aug.
Habitat Fields, prairies, sandy soil. Rocky sites, usually on limestone, shale, or gypsum, on igneous substrates from canyons and slopes in Chihuahuan Desert scrub, grasslands, oak-pine-juniper woodlands, open sites in ponderosa pine-Douglas fir forests.
Elevation 60–600(–1300) m. (200–2000(–4300) ft.) 1000–2700 m. (3300–8900 ft.)
Distribution
from FNA
AR; CO; IL; KS; MI; MN; MO; NE; NM; OK; SD; TX; WI
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, Sonora)
[WildflowerSearch map]
Discussion

Oenothera rhombipetala is primarily a central plains species that has scattered localities in the Midwest to Illinois, Michigan, and Wisconsin, and barely entering the easternmost parts of Colorado and New Mexico.

Oenothera rhombipetala had a broader delimitation (P. A. Munz 1965) until W. Dietrich and W. L. Wagner (1988) divided it into three species (O. clelandii, O. curtissii, and O. rhombipetala), with both of the split-off species being PTH. Evidence gathered by Dietrich and Wagner showed that these PTH species are geographically separated populations of small-flowered plants, and although they are very close morphologically, their distributions and morphological differences suggest that they were each derived independently from O. rhombipetala. Oenothera rhombipetala is self-incompatible.

Oenothera pyramidalis H. Léveillé is a superfluous name and pertains here.

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

Oenotherabrachycarpa occurs from southeastern Arizona in southern Navajo, southeastern Pima, Graham, Santa Cruz, and Cochise counties, east across southern New Mexico to Val Verde and Pecos counties in trans-Pecos Texas.

(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. Oenothera > subsect. Candela Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Megapterium
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. 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. 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. 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. 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 O. heterophylla var. rhombipetala, O. leona, Raimannia rhombipetala Lavauxia brachycarpa, L. graminifolia, L. wrightii, Megapterium brachycarpum, M. brachycarpum var. wrightii, O. australis, O. brachycarpa var. wrightii, O. cespitosa subsp. australis, O. cespitosa var. australis, O. graminifolia, O. wrightii, Pachylophus australis
Name authority Nuttall ex Torrey & A. Gray: Fl. N. Amer. 1: 493. (1840) A. Gray: Smithsonian Contr. Knowl. 3(5): 70. (1852)
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