Douglas’s silverpuffs

Calaïs douglasii de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 7: 85. 1838

Annuals, 5–40 cm; taprooted. Leaves basal. petiolate. blades linear to oblanceolate, 3–25 cm, margins entire, dentate, or pinnately lobed (lobes slender, tapering), apices acute to acuminate. faces ± scurfy-puberulent. Peduncles erect or curved-ascending. ebracteate. Involucres globose to fusiform in fruit, 7–16 mm. Phyllaries: apices erect. acute to acuminate; outer deltate, glabrous or lightly scurfy-puberulent; inner lanceolate, faces often lightly black-villous on margins (midveins often purple-lined, thickened). Florets 5–200; corollas yellow or white, equaling or surpassing phyllaries by 1–3 mm. Cypselae columnar or obconic, 3–10 mm; pappi of (0–)1. 5, white to yellow, brown, or blackish, aristate scales 0.5–7 mm (± arcuate, usually distinctly involute, except subsp. tenella, often abaxially villous, midveins usually tapering distally from thick bases, except subsp. tenella, widths less than ¹/5 bodies). aristae (white or straw-colored, ± stout) barbellate. 2n = 18.

Subspecies 3 (3 in the flora): w United States; nw Mexico.

The geographic patterns of morphologic variability as well as both chloroplast and nuclear DNA markers in Microseris douglasii have been studied by K. Bachmann and J. Battjes (1994) and D. Roelofs and K. Bachmann (1997). Four chloroplast types were identified, two of which were derived by introgression from M. bigelovii or its ancestor. Plants in nature are highly inbred and genetically homozygous, as proposed earlier by K. L. Chambers (1955). Subspecies platycarpha stands well apart in these studies; subsp. tenella is not differentiated molecularly from subsp. douglasii.