Oenothera cespitosa

Herbs perennial, acaulescent or caulescent, usually hirsute or villous, usually also glandular puberulent, or exclusively strig­illose, rarely glabrous; from stout taproot, sometimes lateral roots producing adventitious shoots. Stems (when present), usually ascending or decumbent, unbranched or branched from near base, 0–40 cm. Leaves 1.7–26(–36) × (0.3–)0.5–4.5(–6.5) cm; petiole (0.2–)1.7–11(–14) cm; blade usually oblanceolate to rhombic or spatulate, rarely elliptic, obovate, lanceolate, or linear-oblanceolate, margins irregularly sinuate-dentate, serrate, pinnatifid, lobed, or subentire, apex usually acute to rounded, rarely acuminate. Flowers 1–4(–6) per stem opening per day near sunset, with moderate to strong sweet scent with a rubbery background scent; buds usually erect, rarely recurved (during early development); floral tube (20–)40–140(–165) mm; sepals (15–)18–45(–54) mm; petals white, fading rose or rose pink to dark or deep rose purple, or pink to pale or light rose, or lavender, obovate or obcordate, (16–)20–50(–60) mm; filaments (6–)10–30(–35) mm, anthers (6–)9–17(–20) mm; style (45–)60–180(–185) mm, stigma exserted beyond anthers at anthesis. Capsules straight, curved, falcate, or sigmoid, usually cylindrical to lanceoloid or ellipsoid, sometimes ovoid, usually obtusely 4-angled, (10–)13–50(–68) × 4–9 mm, tapering to a sterile beak 6–8 mm, valve margins with rows of distinct tubercles to sinuate or nearly smooth ridges, dehiscent 1/3–7/8 their length; pedicel (0–)1–40(–55) mm. Seeds numerous in 1 or 2 rows per locule, usually obovoid, oblong, or triangular, rarely suborbicular, 2.1–3.9 × 1–2.6 mm, embryo 1/5–2/3 of seed volume, surface papillose, reticulate or rarely irregularly roughened; seed collar sealed by a thin membrane, this flat or depressed into raphial cavity, when depressed often splitting, becoming separated from seed collar. 2n = 14, 28.

Distribution

w North America, nw Mexico.

Discussion

Subspecies 5 (5 in the flora).

Oenothera cespitosa occurs in a wide array of hab­itats, from grassland, desert scrub, pinyon-juniper woodland, or Arizona chaparral to montane conifer forests, rarely at timberline, at elevations from (450–)800–3370 m. Oenothera cespitosa is self-incompatible (W. L. Wagner et al. 1985; Wagner 2005).

Pachylophus nuttallii Spach is an illegitimate name that pertains here.

Selected References

None.

Lower Taxa

Oenothera cespitosa subsp. cespitosa, Oenothera cespitosa subsp. crinita, Oenothera cespitosa subsp. macroglottis, Oenothera cespitosa subsp. marginata, Oenothera cespitosa subsp. navajoensis

Key

1	Plants glabrous.	> 2
1	Plants hirsute, villous, glandular puberulent, or strigillose.	> 3
2	Floral tubes (28–)35–60(–85) mm; petals fading rose pink to dark rose purple; capsules falcate or sigmoid, valve margins tuberculate.	Oenothera cespitosa subsp. cespitosa
2	Floral tubes (45–)75–110(–153) mm; petals fading pink or rarely pale rose; capsules somewhat curved, valve margins with smooth to irregular, undulate ridges.	Oenothera cespitosa subsp. macroglottis
3	Plants strigillose, rarely glandular puberulent; petals fading rose pink to dark rose purple.	Oenothera cespitosa subsp. cespitosa
3	Plants hirsute or villous, usually also glandular puberulent, rarely only glandular puberulent; petals fading pink to light or pale rose or lavender-rose, sometimes deep rose purple.	> 4
4	Stems unbranched to many-branched, sometimes producing dense clumps 5–50 cm diam.; petals fading rose; seed collar sinuate distally.	Oenothera cespitosa subsp. crinita
4	Stems unbranched to several-branched, not forming clumps; petals fading rose purple or pink to pale rose or lavender; seed collar various.	> 5
5	Petals fading rose or sometimes deep rose purple; capsules ellipsoid to lanceoloid-ellipsoid, falcate or sigmoid; pedicels 0.5–1 mm; seed collar membrane depressed and often splitting at maturity, margin conspicuously sinuate throughout.	Oenothera cespitosa subsp. crinita
5	Petals fading pink to pale rose or lavender; capsules lanceoloid to cylindrical, straight or somewhat curved; pedicels usually (0–)1–40(–55) mm; seed collar membrane neither depressed nor splitting at maturity, margin not sinuate, sometimes somewhat so distally.	> 6
6	Capsules oblong-lanceoloid; buds often recurved when young; floral tube (35–)40–70(–80) mm; plants shaggy-villous, sometimes densely so.	Oenothera cespitosa subsp. navajoensis
6	Capsules cylindrical to lanceoloid-cylindrical; buds erect; floral tube (41–)75–140-(–165) mm; plants hirsute.	> 7
7	Capsules somewhat curved, valve margins with nearly smooth to irregular, undulate ridges; leaf blades oblanceolate to spatulate, margins dentate.	Oenothera cespitosa subsp. macroglottis
7	Capsules straight, valve margins with minute to conspicuous tubercles, these sometimes coalesced into a sinuate ridge; leaf blades usually oblanceolate to narrowly elliptic, rarely lanceolate, margins usually pinnately lobed to dentate, rarely serrate.	Oenothera cespitosa subsp. marginata