Oenothera pallida subsp. trichocalyx
Oenothera pallida
mountain evening primrose, pale evening-primrose, rockweed brush, white-stem evening primrose
single to several from base, usually unbranched.
erect or ascending, single to several from base, unbranched or many-branched throughout, 10–50(–70) cm.
basal rosette usually present at anthesis, 3–5(–7.8) × 0.4–0.8(–1.2) cm;
blade narrowly lanceolate to oblong, margins pinnatifid or dentate.
cauline, rosette usually weakly developed or absent, at least during flowering, sometimes well developed, 1–5(–7.8) × 0.3–1(–1.5) cm;
petiole 0–2(–4.5) cm;
blade lanceolate, oblong, linear-lanceolate, or ovate, margins subentire or remotely denticulate, deeply sinuate-dentate, or pinnatifid, sometimes repand.
buds with free tips 0–0.2 mm;
floral tube 20–30 mm;
sepals 10–18 mm;
petals 10–20 mm.
1–several opening per day near sunset;
buds nodding, weakly quadrangular, with free tips 0–2 mm;
floral tube 15–40 mm;
sepals 10–30 mm, not spotted;
petals white, fading pink to deep pink, broadly obovate or obcordate, (10–)15–25(–40) mm;
filaments 9–15 mm, anthers 3–10 mm;
style 25–55 mm, stigma exserted beyond anthers at anthesis.
spreading to reflexed, straight or contorted.
spreading to reflexed, straight to curved or contorted, cylindrical, obtusely 4-angled, tapering slightly from base to apex, 15–60 × 1.5–2.5 mm;
sessile.
numerous, in 1 row per locule, brownish with dark spots or black, narrowly obovoid, 1.5–2.2 mm.
= 14.
Oenothera pallida subsp. trichocalyx
Oenothera pallida
Subspecies trichocalyx occurs across central to southern Wyoming, eastern Utah, western Colorado, northeastern Arizona, and northwestern New Mexico. Within its range it has slight overlap with subspp. pallida and runcinata. In its purest form, subsp. trichocalyx is the most distinctive phase of Oenothera pallida, but many of the populations have characteristics that approach other subspecies with perennial habit (versus annual) appearing occasionally. Plants that are glabrous, or nearly so, like subsp. pallida, but with apparent short-duration habit and divided leaves like subsp. trichocalyx, occur in southern Wyoming and in the Uinta Basin region of Utah; only more typical plants of subsp. trichocalyx otherwise occur in the region without any current evidence of the presence of subsp. pallida.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Subspecies 4 (4 in the flora).
Oenothera pallida is a poorly understood species currently subdivided into four subspecies (W. L. Wagner et al. 2007) that differ largely in aspect, leaf division, capsule configuration, and pubescence. The variation pattern is rather complex with almost no diagnostic character uniformly distinguishing any one of the subspecies. Instead, each of the subspecies, which are mostly geographically separated although there is some level of overlap, have diagnostic suites of characters that maintain their linkage some of the time, but break down across the geographic area of each so that no single character uniquely identifies it. Each subspecies is characterized by leaf, pubescence, and, often, habit features. The issues with the integrity and intergradations of the subspecies are discussed below.
Oenothera pallida has been determined to be self-incompatible (W. L. Wagner et al. 2007), but K. E. Theiss et al. (2010) determined that although most populations of subsp. pallida are self-incompatible, one near Salt Lake City is self-compatible.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Herbs annual, sometimes perennial from a taproot, when perennial, sometimes with lateral roots producing adventitious shoots, strigillose throughout and villous distally, especially on flower parts. | subsp. trichocalyx |
1. Herbs perennial from a taproot and with lateral roots producing adventitious shoots, glabrous, strigillose, or sparsely villous. | → 2 |
2. Plants glabrous, sometimes strigillose, rarely sparsely villous; leaf blade margins usually subentire or remotely denticulate, rarely pinnatifid; capsules usually contorted to curved. | subsp. pallida |
2. Plants usually strigillose, rarely villous or glabrous; leaf blade margins shallowly sinuate-dentate or denticulate, or deeply sinuate-dentate to pinnatifid, rarely only dentate; capsules usually straight or curved, sometimes contorted. | → 3 |
3. Leaf blades (0.4–)0.7–1.5 cm wide, margins shallowly sinuate-dentate or denticulate. | subsp. latifolia |
3. Leaf blades 0.4–1(–1.5) cm wide, margins usually deeply sinuate-dentate to pinnatifid, rarely dentate only. | subsp. runcinata |
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