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Fremont's evening primrose

Habit Herbs densely strigillose. Herbs (annual or perennial), [shrubs].
Stems

numerous, with numerous short secondary branches, 3–30 cm.

Leaves

gray, (2.8–)3.7–11 × 0.1–0.6(–1.5) cm;

blade linear to narrowly elliptic to narrowly elliptic-lanceolate or narrowly oblanceolate, margins flat, entire or inconspicuously denticulate, apex acute.

alternate or basal;

stipules absent.

Flowers

buds with unequal free tips 1–2(–5) mm;

floral tube (21–)35–65(–80) mm;

sepals (20–)25–30(–37) mm;

petals (17–)25–33(–37) mm;

filaments 13–18 mm, anthers 10–12 mm;

style (45–)55–80(–98) mm.

usually actinomorphic, rarely slightly zygomorphic (in Oenothera), (3 or)4-merous;

stamens 2 times as many, or rarely as many, as sepals;

pollen usually shed in monads, rarely tetrads (Chylismia sect. Lignothera).

Fruit

a dry capsule, usually dehiscent, sometimes indehiscent.

Capsules

ellipsoid to narrowly ellipsoid, often twisted, wings 2–5(–9) mm wide, body 13–30(–65) × 2–6 mm.

Seeds

few to numerous, without hairs or wings, [very rarely with asymmetrical dry wing (Xylonagra)], or with dry (Oenothera), erose or smooth wing, or with thick, papillate wings (Chylismiella).

2n

= 14.

Oenothera macrocarpa subsp. fremontii

Onagraceae tribe Onagreae

Phenology Flowering May–Aug.
Habitat Rocky soil derived from fine-textured sandstone, shale or chalk on rocky hillsides, bluffs, badlands.
Elevation 400–900 m. (1300–3000 ft.)
Distribution
from FNA
KS; NE
[BONAP county map]
North America; Mexico; Central America; South America; West Indies
Discussion

Subspecies fremontii occurs from Franklin and Webster counties in south-central Nebraska south into Kansas to Ellsworth, Hodgeman, and Logan counties; also with disjunct locations in Antelope and Cedar counties in northeastern Nebraska, and Barber County in south-central Kansas. Some specimens from the eastern part of the range, where subsp. fremontii and subsp. macrocarpa are sympatric, appear intermediate between the two subspecies and are difficult to assign.

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

Genera 13, species 265 (12 genera, 199 species in the flora).

Onagreae account for more than half the total genera in Onagraceae and diversified from a center in southwestern North America (L. Katinas et al. 2004). Delimitation of the tribe by W. L. Wagner et al. (2007) differs from previous ones by the exclusion of Gongylocarpus, now in its own tribe, by the segregation of eight genera (Camissoniopsis, Chylismia, Chylismiella, Eremothera, Eulobus, Neoholmgrenia, Taraxia, and Tetrapteron) from Camissonia, and by the inclusion of three previously separate genera (Calylophus, Gaura, and Stenosiphon) in Oenothera. Within the branch of the family that lacks stipules (Gongylocarpeae, Epilobieae, and Onagreae), the last two tribes form a clade that has very strong molecular support (R. A. Levin et al. 2003, 2004), but no obvious morphological synapomorphy. The clade may be defined by a cytogenetic change from the base chromosome number of x = 11 found in Circaeeae, Gongylocarpeae, and Lopezieae, to x = 18 in Epilobieae, and x = 7 in Onagreae; however, these changes could also have occurred independently. Other than the new chromosome number x = 7, the only apparent morphological synapomorphy for Onagreae alone is pollen with prominent apertural protrusions (J. Praglowski et al. 1987, 1989), a character state also found in Circaeeae (Praglowski et al. 1994). The monophyly of Onagreae has moderate (Levin et al. 2004) to strong support (V. S. Ford and L. D. Gottlieb 2007).

(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 > Oenothera macrocarpa Onagraceae > subfam. Onagroideae
Sibling taxa
O. macrocarpa subsp. incana, O. macrocarpa subsp. macrocarpa, O. macrocarpa subsp. oklahomensis
Subordinate taxa
Synonyms O. fremontii, Megapterium fremontii
Name authority (S. Watson) W. L. Wagner: Ann. Missouri Bot. Gard. 70: 194. (1983) Dumortier: Fl. Belg., 89. (1827)
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