Annual herb to 1 m high, rarely perennial, creeping or straggling, to 90 cm high or long, sometimes rooting at the nodes, sometimes mat-forming; stem sometimes purplish, with stipitate glandular hairs on young parts.. Leaves opposite, narrowly ovate or ovate, 1–7 cm long, 0.5–4 cm wide, base obtuse to attenuate, margins subentire to serrate, apex acute to acuminate, short-pubescent to slightly scabridulous; 3–5-veined from base; petiole 5–27 mm long.. Glomerules solitary and terminal, campanulate, 8–13 mm long and 8–30 mm in diameter, with 8–25 1-flowered capitula; subtending bracts lanceolate to obovate, 5–15 mm long, 1–6 mm wide; involucre of capitula 4–5 mm long, 1 mm in diameter, with elongate glands.. Florets white or with blue tinge, 4–5 mm long.. Achenes brown or black, 3 mm long, hairy near apex; pappus a minute crown, pubescent; achene usually surrounded by connate phyllaries topped by scales 2–2.5 mm long.. Fig. 159 (page 755).
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