Annual or perennial herb 15–80 cm, slender and erect; stems pale green or reddish, unbranched or sparsely branched, faintly ribbed, glabrous or distally puberulous.. Leaves proximally opposite (rarely verticillate in 3s), a few distal ones alternate, spreading, pale green, sessile, linear, 5–33 mm long, 0.5–1.5 mm wide, slightly widened at the base, the margins narrowly revolute, entire or sparsely serrulate, obtuse and callous-tipped at the apex, glabrous or rarely glandular-puberulous.. Capitula terminal, solitary (though the distal part of the plant may appear as a lax leafy corymb), ovoid, 3–6 mm long, 14–20 mm in diameter; stalks of individual capitula green tinged with dark purple, 1.5–13 cm long, puberulous distally; phyllaries 26–32, green, lanceolate, 2.5–3.7 mm long, 0.5–1.2 mm wide, acute to acuminate, the margins pale and laciniate, purple glandular-pubescent on the midrib.. Ray florets pale mauve to deep blue (rarely white), 13–21, tube 0.7–1.5 mm long, pubescent, ray 3.5–6 mm long, 1–1.5 mm wide, the apex 2–3-dentate; disc florets yellow or orange, tube 1.3–2 mm long, pubescent proximally, lobes touched with purple, ± 0.2 mm long and acute; anthers yellow, 1.2–1.3 mm long; style cream, 1.5–1.7 mm long.. Achenes ellipsoid, 1–1.6 mm long, 0.6–0.9 mm wide, ± 0.2 mm thick, with paler margins; pappus absent.. Fig. 100 (page 478).
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