familyOnagraceae
subfamilyOnagraceae subfam. Onagroideae
tribeOnagraceae tribe Onagreae
genusOenothera
sectionOenothera sect. Kneiffia
speciesOenothera sessilis

Oenothera sessilis

(Pennell) Munz

Bull. Torrey Bot. Club 64: 291. 1937.

Warren L. Wagner
Basionym: Kneiffia sessilis Pennell Bull. Torrey Bot. Club 46: 366. 1919
Synonyms: Oenothera pilosella subsp. sessilis (Pennell) Straley O. pilosella var. sessilis (Pennell) B. L. Turner
Treatment appears in FNA Volume 10.

Herbs perennial, densely strig­illose, glabrate proximally; from fibrous-roots. Stems ascending, unbranched to few-branched, 30–65 cm. Leaves 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 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, 4-angled, 8–10 × 3–4 mm, stipe 0–2 mm; sessile. Seeds 1 × 0.5 mm. 2n = 56.


Phenology: Flowering May–Jun.
Habitat: Moist remnant prairies in sandy or silty soil.
Elevation: 0–100 m.

Distribution

Ark., La., Tex.

Discussion

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.

Selected References

None.

Lower Taxa

None.
... more about "Oenothera sessilis"
RDF feed
2n chromosome quantity
56 +
4-locular septum architecture
incomplete +
4-locular septum architecture or structure in adjective form
1-locular +
Androecium position
epigynous +
Anther fixation
versatile +
Anther some measurement
0.5 cm5 mm <br />0.005 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
Apex architecture or shape
emarginate +
Apex shape
tapering +  and rounded to truncate +
Author
Warren L. Wagner +
Authority
(Pennell) Munz +
Basal leaf arrangement
alternate +
Basal leaf position
cauline +
Basal leaf presence
absent +
Basal stem length
2.5 cm25 mm <br />0.025 m <br /> (7 cm70 mm <br />0.07 m <br />) +
Basal stem width
0.7 cm7 mm <br />0.007 m <br /> (2.3 cm23 mm <br />0.023 m <br />) +
Base coloration
pale green +  and yellow usually fading orange purple pale-yellow reddish or whitish +
Base reproduction
sterile +
Base shape
pedicel-like +
Basionyms
Kneiffia sessilis +
Berry architecture or shape
nutlike +
Berry dehiscence
indehiscent +  and loculicidal +
Blade margin shape
dentate +, denticulate +, subentire +  and entire +
Blade shape
lanceolate +  and narrowly lanceolate +
Bud arrangement
connivent +
Bud orientation
spreading +
Bud shape
terete +
Capsule architecture
winged +
Capsule architecture or shape
nutlike +
Capsule architecture or structure in adjective form
4-locular +
Capsule condition or texture
dry +
Capsule course
straight +
Capsule dehiscence
indehiscent +  and dehiscent +
Capsule length
0.8 cm8 mm <br />0.008 m <br /> (1 cm10 mm <br />0.01 m <br />) +
Capsule shape
4-angled +  and ellipsoid +
Capsule texture
leathery +
Capsule width
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Carpel quantity
Many (?) +
Cel reproduction
vegetative +
Distalmost node quantity
few +
Distribution
Ark. +, La. +  and Tex. +
Elevation
0–100 m. +
Embryo-sac coating
oily +
Embryo-sac course
straight +
Embryo-sac presence
absent +
Embryo coating
oily +
Embryo course
straight +
Embryo presence
absent +
Endosperm coating
oily +
Endosperm course
straight +
Endosperm presence
absent +
Epidermis coloration
whitish +  and green +
Epidermis relief
exfoliating +
Filament architecture
dithecal +
Filament fixation
basifixed +  and versatile +
Filament fusion
distinct +
Filament some measurement
0.7 cm7 mm <br />0.007 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
Floral-tube atypical some measurement
1.5 cm15 mm <br />0.015 m <br /> (2 cm20 mm <br />0.02 m <br />) +
Floral-tube duration
deciduous +
Floral-tube presence
absent +
Floral-tube pubescence
hispid +, lanate +  and glabrous +
Floral-tube quantity
, +
Floral-tube some measurement
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Flower architecture
zygomorphic +  and actinomorphic +
Flower architecture or arrangement or growth form
solitary +
Flower odor
scented +
Flower part duration
deciduous +
Flower part life cycle
anthesis +
Flower reproduction
bisexual +
Fruit architecture
winged +
Fruit course
curved +  and straight +
Fruit dehiscence
indehiscent +  and dehiscent +
Fruit shape
4-angled +, terete +, tapering +, cylindrical +, ellipsoid +, clavate +, ovoid ellipsoid +  and cylindrical rhombic-obovoid or globose +
Habitat
Moist remnant prairies in sandy or silty soil. +
Hair height or length or size
short +
Hair position relational
interlocking +
Herb architecture
caulescent +
Herb duration
perennial +
Herb growth form
suffrutescent +
Herb pubescence
glabrate +
Herb texture
fleshy +
Indusium architecture
peltate +
Indusium prominence
conspicuous +
Inflorescence orientation
nodding +
Inflorescence position
axillary +
Lateral root orientation
spreading +
Leaf-axil orientation
nodding +  and erect +
Leaf architecture
simple +
Leaf arrangement
alternate +
Leaf atypical some measurement
10 cm100 mm <br />0.1 m <br /> (13 cm130 mm <br />0.13 m <br />) +
Leaf condition
later +
Leaf duration
deciduous +
Leaf position
cauline +
Leaf presence
absent +
Leaf some measurement
3 cm30 mm <br />0.03 m <br /> (10 cm100 mm <br />0.1 m <br />) +
Lobe arrangement or course or shape
linear +
Lobe quantity
4 (?) +
Locule arrangement or growth form
clustered +
Locule quantity
many +
Margin architecture
sessile +
Margin position
cauline +
Margin shape
subentire +  and undulate +
Mouth condition
closing +
Nectary presence
absent +
Number of lower taxa
0 +
Ovary architecture
pedicellate +  and sessile +
Ovary architecture or structure in adjective form
1-locular +
Ovary position
inferior +
Ovule architecture
bitegmic +
Ovule arrangement or growth form
clustered +
Ovule orientation
anatropous +
Ovule quantity
1 +  and 8 +
Perianth position
epigynous +
Petal arrangement
imbricate +
Petal arrangement or shape
convolute +
Petal character
not color +
Petal coloration
fading pale-pink +  and bright-yellow +
Petal presence
absent +
Petal quantity
4 +
Petal shape
obcordate +  and obovate +
Petal some measurement
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
Petiole some measurement
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Phenology
Flowering May–Jun. +
Pollen-grain dehiscence or orientation
longitudinal +
Pollen arrangement
singly +
Pollen reproduction
fertile +
Polyad arrangement
singly +
Proximal part reproduction
sterile +
Publication title
Bull. Torrey Bot. Club +
Publication year
1937 +
Raphide quantity
abundant +
Reference
None +
Rosette position
basal +  and cauline +
Row atypical quantity
2 (4) +
Row quantity
2 +  and 1 +
Secretion condition
wet +
Secretion condition or texture
dry +
Secretion relief
papillate +
Secretion shape
clavate +  and globose +
Seed arrangement or growth form
clustered +
Seed atypical quantity
1 (160) +
Seed length
1 cm10 mm <br />0.01 m <br /> (?) +
Seed quantity
numerous +
Seed relief
sculptured +  and smooth +
Seed shape
ovoid +
Seed size
reduced +
Seed width
0.5 cm5 mm <br />0.005 m <br /> (?) +
Sepal architecture or dehiscence
splitting +
Sepal arrangement
separating +
Sepal arrangement or dehiscence
valvate +
Sepal coloration
purple +, pink +, red +  and green +
Sepal duration
deciduous +
Sepal fusion
coherent +
Sepal orientation
reflexed +
Sepal quantity
4 +
Sepal some measurement
1 cm10 mm <br />0.01 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
Septum architecture
incomplete +
Septum arrangement
parietal +, axile +  and placentation +
Septum fragility
fragile +
Septum presence
absent +
Septum width
thin +
Series length or size
longer +
Series quantity
2 +
Series size
unequal +
Series variability
equal +
Set length or size
longer +
Set quantity
2 +
Set variability
equal +
Shoot orientation
arising +
Shrub architecture
unarmed +
Shrub growth form
not clonal +
Shrub habitat
aquatic +, amphibious +  and terrestrial +
Slit dehiscence or orientation
longitudinal +
Spike architecture
leafy +
Stamen quantity
8 +
Stamen size
in 2 unequal series +  and subequal +
Stamen size or quantity
2 times as many or as many as sepals +
Stem architecture
unbranched +  and few-branched +
Stem growth form or orientation
decumbent +
Stem orientation
ascending +
Stem some measurement
30 cm300 mm <br />0.3 m <br /> (65 cm650 mm <br />0.65 m <br />) +
Stigma architecture
peltate +
Stigma development
developing +
Stigma quantity
1 +
Stigma shape
divided +
Stipe architecture
sessile +
Stipe some measurement
0 cm0 mm <br />0 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Stipule architecture
petiolate +  and sessile +
Stipule duration
caducous +
Stipule position
intrapetiolar +
Stipule presence
absent +
Stipule size
small +
Style pubescence
pubescent +  and glabrous +
Style quantity
1 +
Style some measurement
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
Subshrub architecture
unarmed +
Subshrub growth form
not clonal +
Subshrub habitat
aquatic +, amphibious +  and terrestrial +
Surface architecture
smooth +, reticulate +  and furrowed +
Surface architecture or shape
entire +
Surface condition
wet +
Surface duration
persisting +
Surface life cycle
anthesis +
Surface prominence
obscured +
Surface quantity
7 (?) +
Surface relief
papillose +
Surface shape
beaded +
Synonyms
Oenothera pilosella subsp. sessilis +  and O. pilosella var. sessilis +
Taxon family
Onagraceae +
Taxon name
Oenothera sessilis +
Taxon parent
Oenothera sect. Kneiffia +
Taxon rank
species +
Tetrad arrangement
singly +
Tetrad dehiscence
3(-5)-aperturate +
Tip fusion
free +
Tip some measurement
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Valve midrib architecture
sessile +
Valve midrib dehiscence
dehiscent +
Valve midrib prominence
raised +
Viscin thread dehiscence or orientation
longitudinal +
Viscin thread fusion
united +
Volume
Volume 10 +
Wall texture
woody +  and hard +
Wing architecture
smooth +  and erose +
Wing condition or texture
dry +
Wing relief
papillate +
Wing width
thick +