FNA: Oenothera podocarpa vs. Oenothera sessilis

	Oenothera podocarpa	Oenothera sessilis

Habit	Herbs annual, villous proximally, glabrate, strigillose and/or glandular puberulent distally, leaves glabrate to densely villous, glabrate in age; from stout taproot.	Herbs perennial, densely strigillose, glabrate proximally; from fibrous roots.
Stems	ascending to erect, unbranched or well-branched at base and distally, 15–100 cm.	ascending, unbranched to few-branched, 30–65 cm.
Leaves	in a basal rosette and cauline, basal 3–15 × 0.5–1 cm, blade lyrate; cauline 1–9 × 0.1–0.8 cm, blade linear to very narrowly elliptic or narrowly lanceolate, margins sinuate-dentate to subentire.	in a basal rosette and cauline, basal 2.5–7 ×0.7–2.3 cm, petiole 1–1.5 cm, blade oblanceolate, margins subentire, undulate; cauline (3–)6–7(–9) ×(0.3–)0.6–0.8(–1.1) cm, sessile, blade lanceolate to narrowly lanceolate, margins subentire.
Inflorescences		nodding, flowers in axils of distalmost few nodes.
Flowers	4-merous, zygomorphic, opening at sunset; floral tube 6–10 mm; sepals 6–12 mm; petals white, fading pink to red, narrowly obovate, 5.5–9.5 mm, short-clawed; filaments 4–6 mm, anthers 2–3 mm, pollen 90–100% fertile; style 11–19 mm, stigma surrounded by anthers at anthesis.	opening near sunrise; buds with free tips 1–2 mm, connivent to spreading; floral tube 10–15(–20) mm; sepals 10–18 mm; petals bright yellow, fading pale pink, 15–25 mm; filaments 7–9 mm, anthers 5–8 mm, pollen 85–100% fertile; style 10–12 mm, stigma exserted beyond anthers at anthesis.
Capsules	ellipsoid or narrowly obovoid, narrowly 4-winged, furrowed between wings, 6–8 × 2–3 mm, narrowed at base, stipe 0 mm; sessile.	ellipsoid, 4-angled, 8–10 × 3–4 mm, stipe 0–2 mm; sessile.
Seeds	4, yellowish to reddish brown, 2–3 × 1–1.5 mm.	1 × 0.5 mm.
2n	= 14.	= 56.

	Oenothera podocarpa	Oenothera sessilis
Phenology	Flowering (May–)Jun–Oct.	Flowering May–Jun.
Habitat	Disturbed sites, sandy washes, slopes, grasslands, meadows, pinyon-juniper or ponderosa pine woodlands, on volcanic cinders.	Moist remnant prairies in sandy or silty soil.
Elevation	700–2800 m. (2300–9200 ft.)	0–100 m. (0–300 ft.)
Distribution	AZ; NM; Mexico (Chihuahua, Durango, Sonora)	AR; LA; TX
Discussion	Oenothera podocarpa occurs in Arizona from eastern Mohave County south through the mountains of central Arizona to eastern Pima County and the southwestern quarter of New Mexico, and in Mexico southward in the Sierra Madre Occidental to eastern Sonora and throughout the western halves of Chihuahua and Durango. P. H. Raven and D. P. Gregory (1972[1973]) determined O. podocarpa to be self-compatible and primarily autogamous. (Discussion copyrighted by Flora of North America; reprinted with permission.)	Oenothera sessilis is relatively rare within its range and has a narrow overall distribution, occurring in Ashley, Phillips, Prairie, and St. Francis counties in Arkansas, Allen, Claiborne, and Tensas parishes in Louisiana, and Galveston County in Texas. Oenothera sessilis appears to be relatively rare and may no longer occur in Texas; it was last collected there in the 1840s by Lindheimer on Galveston Island. It is also rare in Louisiana but has been collected in recent decades. It is currently most common in Arkansas. P. A. Munz (1937, 1965) treated this taxon as O. sessilis, but G. B. Straley (1977) in his revision of sect. Kneiffia placed it as a subspecies of O. pilosella based on a common octoploid (2n = 56) chromosome number, morphology, and field studies. K. N. Krakos et al. (2014), based on new field studies, controlled greenhouse breeding experiments, and phylogenetic data found that this taxon differs morphologically from O. pilosella by having consistently shorter stature and smaller flowers, is self-compatible, and does not form a monophyletic group with O. pilosella in molecular analyses, and is here reinstated as a distinct species. Oenothera sessilis is in the Center for Plant Conservation’s National Collection of Endangered Plants as O. pilosella subsp. sessilis. (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. Gaura > subsect. Gaura	Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Kneiffia
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. 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. 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. 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	Gaura podocarpa, G. brassicacea, G. glandulosa, G. gracilis, G. hexandra subsp. gracilis, G. strigillosa, O. hexandra subsp. gracilis	Kneiffia sessilis, O. pilosella subsp. sessilis, O. pilosella var. sessilis
Name authority	(Wooton & Standley) Krakos & W. L. Wagner: PhytoKeys 28: 68. (2013)	(Pennell) Munz: Bull. Torrey Bot. Club 64: 291. (1937)
Web links	WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local Web sites: LA Plants WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Oenothera sessilis

Habit

Herbs annual, villous proximally, glabrate, strigillose and/or glandular puberulent distally, leaves glabrate to densely villous, glabrate in age; from stout taproot.

Herbs perennial, densely strigillose, glabrate proximally; from fibrous roots.

Stems

ascending to erect, unbranched or well-branched at base and distally, 15–100 cm.

ascending, unbranched to few-branched, 30–65 cm.

Leaves

in a basal rosette and cauline, basal 3–15 × 0.5–1 cm, blade lyrate;

cauline 1–9 × 0.1–0.8 cm, blade linear to very narrowly elliptic or narrowly lanceolate, margins sinuate-dentate to subentire.

in a basal rosette and cauline, basal 2.5–7 ×0.7–2.3 cm, petiole 1–1.5 cm, blade oblanceolate, margins subentire, undulate;

cauline (3–)6–7(–9) ×(0.3–)0.6–0.8(–1.1) cm, sessile, blade lanceolate to narrowly lanceolate, margins subentire.

Inflorescences

nodding, flowers in axils of distalmost few nodes.

Flowers

4-merous, zygomorphic, opening at sunset;

floral tube 6–10 mm;

sepals 6–12 mm;

petals white, fading pink to red, narrowly obovate, 5.5–9.5 mm, short-clawed;

filaments 4–6 mm, anthers 2–3 mm, pollen 90–100% fertile;

style 11–19 mm, stigma surrounded by anthers at anthesis.

opening near sunrise;

buds with free tips 1–2 mm, connivent to spreading;

floral tube 10–15(–20) mm;

sepals 10–18 mm;

petals bright yellow, fading pale pink, 15–25 mm;

filaments 7–9 mm, anthers 5–8 mm, pollen 85–100% fertile;

style 10–12 mm, stigma exserted beyond anthers at anthesis.

Capsules

ellipsoid or narrowly obovoid, narrowly 4-winged, furrowed between wings, 6–8 × 2–3 mm, narrowed at base, stipe 0 mm;

sessile.

ellipsoid, 4-angled, 8–10 × 3–4 mm, stipe 0–2 mm;

sessile.

Seeds

4, yellowish to reddish brown, 2–3 × 1–1.5 mm.

1 × 0.5 mm.

= 14.

= 56.

Oenothera sessilis

Phenology

Flowering (May–)Jun–Oct.

Flowering May–Jun.

Habitat

Disturbed sites, sandy washes, slopes, grasslands, meadows, pinyon-juniper or ponderosa pine woodlands, on volcanic cinders.

Moist remnant prairies in sandy or silty soil.

Elevation

700–2800 m. (2300–9200 ft.)

0–100 m. (0–300 ft.)

Distribution

AZ; NM; Mexico (Chihuahua, Durango, Sonora)

AR; LA; TX

Discussion

Oenothera podocarpa occurs in Arizona from eastern Mohave County south through the mountains of central Arizona to eastern Pima County and the southwestern quarter of New Mexico, and in Mexico southward in the Sierra Madre Occidental to eastern Sonora and throughout the western halves of Chihuahua and Durango. P. H. Raven and D. P. Gregory (1972[1973]) determined O. podocarpa to be self-compatible and primarily autogamous.

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

Oenothera sessilis is relatively rare within its range and has a narrow overall distribution, occurring in Ashley, Phillips, Prairie, and St. Francis counties in Arkansas, Allen, Claiborne, and Tensas parishes in Louisiana, and Galveston County in Texas. Oenothera sessilis appears to be relatively rare and may no longer occur in Texas; it was last collected there in the 1840s by Lindheimer on Galveston Island. It is also rare in Louisiana but has been collected in recent decades. It is currently most common in Arkansas. P. A. Munz (1937, 1965) treated this taxon as O. sessilis, but G. B. Straley (1977) in his revision of sect. Kneiffia placed it as a subspecies of O. pilosella based on a common octoploid (2n = 56) chromosome number, morphology, and field studies. K. N. Krakos et al. (2014), based on new field studies, controlled greenhouse breeding experiments, and phylogenetic data found that this taxon differs morphologically from O. pilosella by having consistently shorter stature and smaller flowers, is self-compatible, and does not form a monophyletic group with O. pilosella in molecular analyses, and is here reinstated as a distinct species.

Oenothera sessilis is in the Center for Plant Conservation’s National Collection of Endangered Plants as O. pilosella subsp. sessilis.

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

Source

FNA vol. 10.

Parent taxa

Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Gaura > subsect. Gaura

Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Kneiffia

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. 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. 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. 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

Gaura podocarpa, G. brassicacea, G. glandulosa, G. gracilis, G. hexandra subsp. gracilis, G. strigillosa, O. hexandra subsp. gracilis

Kneiffia sessilis, O. pilosella subsp. sessilis, O. pilosella var. sessilis

Name authority

(Wooton & Standley) Krakos & W. L. Wagner: PhytoKeys 28: 68. (2013)

(Pennell) Munz: Bull. Torrey Bot. Club 64: 291. (1937)

Web links

Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).

Choose a data source: Flora of North America

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Oenothera podocarpa

Oenothera sessilis

Oenothera podocarpa

Oenothera sessilis