FNA: Oenothera pallida subsp. pallida vs. Oenothera sect. Anogra

Phenology

Flowering May–Sep.

Habitat

Sandy soil, dunes, disturbed areas, alkaline soil.

Elevation

1100–2000 m. (3600–6600 ft.)

Distribution

AZ; CO; ID; NM; NV; OR; UT; WA; WY; BC

[BONAP county map]

w North America; n Mexico; c North America

Discussion

The distribution of subsp. pallida centers in the intermountain region from Oregon and Washington east of the mountains, adjacent southern British Columbia, south through southern Idaho, Wyoming, western half of Utah, southern Nevada, to northern Arizona, northwestern New Mexico, and adjacent southwestern Colorado. There are morphological intermediates with subspp. runcinata and trichocalyx. Densely strigillose plants occur within the range of subsp. pallida, especially near the St. Anthony Dunes in Idaho, and have been referred to as var. idahoensis.

Baumannia douglasiana Spach is an illegitimate name that pertains here.

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

Species 8 (7 in the flora).

Section Anogra consists of eight species (17 taxa) native to western North America including Mexico, found usually in dry, sandy soil in a wide variety of habitats in the Chihuahuan, Great Basin, Mojave, and Sonoran deserts, to grasslands and open sites in montane forest, -50 to 3300 m. Only one species, Oenothera wigginsii Klein, occurs entirely outside the United States, while four others occur within the flora area but extend into northern Mexico. Section Anogra is included within a strongly supported clade with the two species of sect. Kleinia in recent molecular studies (R. A. Levin et al. 2004; M. E. K. Evans et al. 2005, 2009). The support levels for the topology within this clade are generally very weak, with only a few taxa grouping into moderately to strongly supported groups (for example, members of O. pallida complex, O. deltoides + O. wigginsii, O. californica + O. arizonica and O. neomexicana).

Species of sect. Anogra have vespertine flowers that are outcrossed and pollinated by hawkmoths or have flowers that are partly autogamous (D. P. Gregory 1964; W. M. Klein 1964, 1970). In Oenothera deltoides the capsule valves split open widely and disperse seeds, while the entire plant forms a so-called tumbleweed. Other species in the section appear to have more passive seed dispersal; the capsules dehisce while the plant remains rooted. The basal rosette may not be evident at time of flowering or not developed. When this is the case, or when the dimensions of the basal leaves are very similar to the cauline ones, only one range for leaf dimensions is given.

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

Key

1. Herbs winter-annual or short-lived perennial from a taproot.	→ 2
2. Sepals conspicuously maroon-spotted.	O. arizonica
2. Sepals without maroon spots.	→ 3
3. Plants villous throughout, also strigillose on leaves and distal parts; leaf blade margins coarsely repand-dentate or -pinnatifid.	O. engelmannii
3. Plants villous, strigillose, or glabrous, sometimes more densely villous or strigillose distally; leaf blade margins subentire to sinuate-dentate or remotely denticulate, sometimes pinnatifid.	→ 4
4. Capsules 2.5–5 mm diam.; sepals (13–)15–35 mm.	O. deltoides
4. Capsules 1.5–2.5 mm diam.; sepals 10–18 mm.	O. pallida
1. Herbs perennial, from a taproot, also with lateral roots producing adventitious shoots or with long, fleshy roots.	→ 5
5. Buds fluted in distal 1/2, with free tips 1–9 mm; plants from relatively long, fleshy roots.	O. deltoides
5. Buds quadrangular in distal 1/2, with free tips 0–4 mm; plants from a taproot and with lateral roots producing adventitious shoots.	→ 6
6. Plants glabrous, sometimes strigillose on leaves and/or glandular puberulent distally, at least on floral tube; leaf blades 0.3–0.6(–1) cm wide, narrowly oblong to oblong- lanceolate, margins usually entire.	O. nuttallii
6. Plants villous, strigillose, glabrate, or glabrous, not glandular puberulent; leaf blades (0.3–)1–2.5 cm wide, usually ovate, oblong to lanceolate or linear-lanceolate, oblanceolate, or spatulate, rarely rhombic-ovate, margins usually sinuate-dentate to pinnatifid or subentire, rarely entire.	→ 7
7. Capsules erect or strongly ascending.	O. neomexicana
7. Capsules spreading to reflexed.	→ 8
8. Capsules 2–3.5 mm diam.; stems decumbent or ascending.	O. californica
8. Capsules 1.5–2.5 mm diam.; stems erect or ascending.	O. pallida