Arnoseris

Annuals, (5-)10-30+ cm; taprooted. Stems 1-10+ (scapiform), erect, simple or branched distally, glabrous. Leaves mostly basal; obscurely petiolate; blades oblanceolate to spatulate, margins dentate (faces usually scabridulous, mostly near margins). Heads borne singly or (2-3) in loose, corymbiform arrays. Peduncles inflated (fistulose) distally, not bracteate. Calyculi 0 or of 1-10+, lanceolate bractlets. Involucres broadly campanulate or urceolate, 4-8 mm diam. Phyllaries 10-22+ in 1(-2) series (basally connate), lanceolate to lance-linear (abaxially keeled proximally), equal or subequal, margins little, if at all, scarious, apices acuminate. Receptacles flat, pitted, glabrous, epaleate. Florets 20-50+; corollas yellow. Cypselae dark brown, obovoid, not beaked, ribs 8-10 (3-5 stronger), stramineous, faces smooth or rugose between ribs, glabrous; pappi 0. . = 9.

Fls all ligulate and perfect, yellow; invol campanulate, becoming broader in fr, its bracts equal and uniseriate, becoming keeled with an enlarged and indurate midrib in fr, rarely minutely and scantily calyculate; achenes obovoid, 8-10-ribbed, some of the ribs commonly stronger than the others and making the achenes subangular; pappus none; branching, annual, lactiferous herbs with well developed basal lvs, the stem sparsely and minutely bracteate or essentially naked, becoming simple, monocephalous, and strictly scapose in depauperate plants. Monotypic.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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