6. Chylismia claviformis (Torrey & Frémont) A. Heller, Muhlenbergia. 2: 105. 1906. (as Chylisma clavaeformis).
[F]
Oenothera claviformis Torrey & Frémont in J. C. Frémont, Rep. Exped. Rocky Mts., 314. 1845 (as clavaeformis); Camissonia claviformis (Torrey & Frémont) P. H. Raven; Chylismia scapoidea (Torrey & A. Gray) Nuttall ex Raimann var. claviformis (Torrey & Frémont) Small; O. scapoidea Torrey & A. Gray var. claviformis (Torrey & Frémont) S. Watson
Herbs annual, glabrous, strigillose, glandular puberulent, or, sometimes, villous. Stems branched mostly from base, 3–70 cm. Leaves primarily in basal rosette, cauline reduced or absent, 1.5–20 × 0.3–3.5 cm; petiole 0.7–12 cm; blade usually pinnately lobed, sometimes lateral lobes poorly developed or absent, terminal lobe usually narrowly ovate to lanceolate, sometimes cordate or subcordate, 0.8–9 × 0.2–4.5 cm, margins dentate, sinuate-dentate, or serrate, brown oil cells conspicuously lining veins abaxially. Racemes nodding, elongating after anthesis. Flowers opening at sunset or sunrise; buds with or without subapical or apical free tips; floral tube 2–6.5 mm, villous inside proximally; sepals 2–8 mm; petals pale to bright yellow or white, sometimes red- or purple-dotted near base, fading purple, sometimes red or orange, or not changing color, 1.5–8 mm; stamens subequal, filaments 1.5–5.5 mm, anthers 1.5–6 mm, ciliate; style 5–16 mm, stigma exserted beyond anthers at anthesis. Capsules ascending to spreading, clavate, 8–40 mm; pedicel 4–40 mm. Seeds 0.6–1.5 mm.
Subspecies 11 (10 in the flora): w United States, nw Mexico.
P. H. Raven (1962) subdivided this species into 12 subspecies and, subsequently (1969), he combined two of them. The latter approach is used here. Only subsp. Wigginsii P. H. Raven does not occur in the United States; its narrow range is restricted to northern Baja California. Raven (1962, 1969) determined this species to be self-incompatible.
Chylismia claviformis is the most complex and, along with C. scapoidea, the most widely distributed species of the genus. The central part of its geographical range is occupied by five closely related white-petaled subspecies (aurantiaca, claviformis, funerea, integrior, and peeblesii) that are very similar morphologically. South of this area four additional subspecies occur, all yellow-petaled (peirsonii, rubescens, wigginsii, and yumae). These four subspecies have sepals and petal color similar to those of C. brevipes, and P. H. Raven (1962, 1969) thought it likely that they were derived following hybridization between that species and one of the white-petaled populations of C. claviformis. North of the range of the white-petaled subspecies are found two additional yellow-petaled subspecies (cruciformis and lancifolia). Most populations of subsp. Cruciformis consist of plants in which the flowers open in the early morning; in all other subspecies the flowers open in the late afternoon (Raven 1962, 1969). The following key will separate them, but there are many intergrades among the subspecies so that not all specimens will be easily identified.
