26. Clarkia xantiana A. Gray, Proc. Boston Soc. Nat. Hist. 7: 146. 1859.
[E F]
Gunsight or Xantus’s clarkia
Stems erect, to 80 cm, glabrous, glaucous. Leaves: petiole 0–2 mm; blade linear to lanceolate, 2–6 cm. Inflorescences open racemes, axis straight; buds pendent. Flowers: floral tube 2–5 mm; sepals reflexed together to 1 side; corolla rotate, petals lavender to reddish purple, lavender-pink, or white, often with white-surrounded dark reddish purple spot distally, clawed, 2-lobed, with slender central tooth, 1–3 mm, 6–20 mm; stamens 8, in 2 unequal sets, outer anthers lavender to purple, inner smaller, paler; ovary 8-grooved; stigma exserted or not beyond anthers. Capsules 15–25 mm; pedicel 0–5 mm. Seeds brown, 1.3–1.5 mm, tuberculate, crest minute.
Subspecies 2 (2 in the flora): California.
Originally placed in the group now delimited as subsect. Phaeostoma by H. Lewis and M. E. Lewis (1955), Clarkia xantiana was treated as a monotypic subsect. Xantianae within sect. Phaeostoma by K. E. Holsinger (1985), based mainly on its unusual 2-lobed petals with a tooth in the sinus. Molecular data (R. A. Levin et al. 2004) placed C. xantiana close to C. bottae, and both of them close to but not within sect. Phaeostoma. Both species share the chromosome number 2n = 18 with C. jolonensis.
SELECTED REFERENCE Eckhart, V. M., M. A. Geber, and C. McGuire. 2004. Experimental studies of selection and adaptation in Clarkia xantiana (Onagraceae). I. Sources of phenotypic variation across a subspecies border. Evolution 58: 59–70.
