Shrubs, subshrubs, or herbs, erect or prostrate, moderately to much branched; branches erect to spreading. Cortex of old branches glabrous, smooth, brown, reddish, yellowish brown, or greyish; young branches green, striate, with long or short glandular-hairs, sometimes with additional eglandular, bristly hairs. Leaves alternate, filiform, lanceolate, oblong or spathulate in outline, entire or serrate or dentate to pinnatifid, with conspicuous short glands, in some species with glandular-hairs and/or bristly hairs. Capitula discoid, homogamous, solitary to laxly corymbose, terminal. Involucre narrowly to broadly cyathiform (fan-shaped when pressed). Involucral bracts generally cartilaginous, lanceolate to narrowly oblong or narrowly obovate, dorsally glandular and marginally ciliate, apically acute to narrowly acuminate. Receptacle flat, epaleate. Florets yellow or occasionally purplish or turning purplish with age, 5-lobed, perfect; corolla glandular-hairy, gradually attenuating toward base, basally widened into ring-shaped foot; corolla lobes narrowly triangular to triangular, glandular, in most species with acute hairs apically. Style terete, bifid, basally widened into bulb-shaped foot with large cells; style-branches semiterete to flattened, linear to narrowly spathulate, erecto-patent. Anthers flat with obtuse to acute, sterile, apical appendage, and long, more or less branched tails basally; endothecial tissue polarized. Pollen (see above). Achenes terete to somewhat flattened, narrowly cylindrical to cylindrical, often slightly tapering toward base, 12-20-costate, with more or less protruding knob-like horns apically on ribs, glandular-hairy, with or without scattered twin-hairs. Crystals always small, several in each cell, often occurring as crystal sand. Pappus of barbellate or plumose bristles in one or several rows, with small or large, entire or incised to almost bristle-like external scales.
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Annual herb, occasional biennual, sometimes with slightly woody base, 5–60 cm high, much branched; stems glandular and scabridulous-hairy.. Leaves linear to narrowly obovate, 0.5–3.5(–5) cm long, 0.1–0.3 cm wide, base cuneate or attenuate, margin entire or with few teeth, apex obtuse and mucronate, acute or 3-toothed, glandular and scabridulous on both surfaces.. Capitula 5–13 mm long, solitary on small branches but these forming small to large, lax, leafy corymbs; phyllaries green with yellow tips, porrect, after achenes have fallen reflexed, lanceolate, 2–10 mm long, acute, scabridulous and glandular; receptacle honeycombed, with triangular bumps to 0.3 mm long.. Florets pale yellow, 14–30, all hermaphrodite, tube cylindric, 3.2–5 mm long, sparsely glandular, lobes 0.1–0.2 mm except for a single adaxial one which is 1.3–1.5 mm long, glandular, anthers 2.3–2.5 mm long, style 6–6.5 mm long.. Achenes cylindric, 3.7–4.5 mm long, ribbed, pilose and sparsely glandular; pappus white, 5–6 mm long, plumose, with an outer row of deeply incised scales to 2 mm long.. Fig. 64.
Annual herb, up to 0.6 m high. Leaves entire or shallowly and bluntly serrate. Involucral bracts acute to obtuse. Corolla zygomorphic, 1 lobe much larger than others, lobes erect. Pappus with conspicuous outer scales, bristles plumose. Flowers yellow becoming purplish with age.
A branched aromatic annual herb, woody below, up to about 1 ft. high
Yellow florets turning purplish, in heads 1/2 in. long.
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