174. Amphipappus Torrey & A. Gray, Boston J. Nat. Hist. 5: 107. 1845.
[Greek amphi-, double or two, and pappos, pappus alluding to dimorphic pappi, ray cypselae and disc cypselae]
Guy L. Nesom
Shrubs, 30–60 cm (rounded). Stems erect (bark whitish), intricately branched, becoming leafless and spinescent, branchlets glabrous or densely, hirtellous. Leaves cauline; alternate (ascending); petiolate to subsessile; blades 1-nerved, obovate to narrowly elliptic, margins entire, faces glabrous or hirtellous, often resinous. Heads radiate (discoid), (2–4) in glomerate, terminal clusters, these in corymbiform arrays. Involucres turbino-cylindric, 4–5.5 × 2–3 mm. Phyllaries 7–12 in 3 series, greenish white, 1-nerved (outer keeled), ovate to elliptic, unequal, thin-indurate, margins not scarious, faces glabrous. Receptacles flat, pitted, epaleate. Ray florets (0–)1–2, pistillate, fertile; corollas yellow (laminae slightly longer than involucres). Disc florets 3–7, functionally staminate; corollas yellow, tubes longer than narrowly funnelform throats (nerves 1, yellow, not resinous), lobes 5, reflexed or coiling back, lanceolate; style-branch appendages triangular (nonfunctional, lacking stigmatic lines). Cypselae (ray) oblong-elliptic to obovoid, ± flattened, 2-nerved, faces moderately villous; pappi persistent, of 15–20, stramineous, basally connate, flattened, slender, barbellate, apically attenuate bristles in 1 series (disc bristles longer than ray, sometimes undulate or twisted). x = 9.
Species 1: sw United States.
Amphipappus is characterized by its low-shrubby, intricately branched habit and corymbiform, glomerate clusters of small, few-flowered heads, functionally staminate disc florets, and pappi of short, barbellate bristles, the fertile ray cypselae with pappi of shorter, flattened bristles. The genus is restricted to the Mojave Desert of California, Nevada, Utah, and Arizona where these states are contiguous.
Porter, Ced. L. 1943. The genus Amphipappus Torr. and Gray. Amer. J. Bot. 30: 481–483.