Gen. Sp. Pl., 30. 1816.
Annuals, biennials, or perennials, 10–80+ cm. Stems erect or spreading, branched from bases or throughout. Leaves mostly cauline; all or mostly opposite or all or mostly alternate; petiolate or sessile; blades usually 1–2-ternately lobed (blades or lobes mostly filiform, lanceolate, linar, oblanceolate, oblong, or ovate), ultimate margins toothed or entire, faces sparsely to densely hairy (hairs white, straight, conic or fusiform, 0.1–0.3 or 0.3–0.8 mm), often gland-dotted as well. Heads radiate, borne singly or in loose, corymbiform arrays. Involucres ± hemispheric or broader, 6–14+ mm diam. Phyllaries persistent, 8–18+ in ± 2 series (reflexed in fruit, distinct, subequal or outer smaller, mostly lanceolate or oblanceolate, thin-herbaceous, margins membranous, rarely purplish). Receptacles convex, smooth or knobby, epaleate. Ray florets 5–15, pistillate, fertile; corollas yellow (sometimes pale). Disc florets 25–120+, bisexual, fertile; corollas yellow (hairy), tubes shorter than or about equaling cylindric or campanulate to funnelform throats, lobes 5, deltate to lance-ovate. Cypselae obpyramidal, 4-angled, ± hirtellous to ± sericeous; pappi persistent, of 6–12 distinct, spatulate or oblanceolate to ovate or quadrate, basally and/or medially thickened, distally and/or laterally scarious scales in ± 1 series (apices usually muticous, sometimes some or all ± aristate). x = 12.
sw United States, Mexico, South America.
Species ca. 10 (4 in the flora).
Bahia dissecta is treated here in Amauriopsis; B. oppositifolia and B. woodhousei are treated in Picradeniopsis; B. nudicaulis is treated in Platyschkuhria. These departures from the treatment of Bahia in a broad sense by W. L. Ellison (1964) are consistent with findings by B. G. Baldwin et al. (2002).
|1||Leaves all or mostly opposite (distal sometimes alternate)||> 2|
|1||Leaves all or mostly alternate (proximal sometimes opposite)||> 3|
|2||Annuals; leaf lobes filiform to linear, 0.5–1(–2+) mm wide, faces sparsely scabrellous; pappi 0.5–1 mm||Bahia bigelovii|
|2||Perennials; leaf lobes lanceolate to oblong, 2–5(–20+) mm wide, faces densely scabrello-canescent; pappi 1–1.5 mm||Bahia absinthifolia|
|3||Leaf lobes filiform to linear, 0.5–1.5(–3+) mm wide; pappus scales (outer cypselae) ± ovate to quadrate, 0.5–1 mm, apices ± muticous or (innermost cypselae) lanceolate to lance-subulate, 1–2.5 mm, apices ± aristate||Bahia biternata|
|3||Leaf lobes oblong or ovate to oblanceolate, (1–)2–6(–8+) mm wide; pappus scales (all cypselae) spatulate to oblanceolate, 1–1.5 mm, apices ± muticous||Bahia pedata|