Cotula myriophylloides Harv.

Floating aquatic annual herb. Stems 40-240 mm long, glabrous, somewhat spongy, 1.5-2.5 mm in diameter. Leaves opposite, spreading, palmatisect, 20-40 x 5.0-10 mm; base dilated, forming a prominent sheath around the stem, sheath 2.0-3.0 mm long; lobes linear, 20-35 x 0.2-1 mm, ± terete, turgid, dark green, glabrous, apices acute, margins entire. Capitula heterogamous, disciform, solitary, terminal, pedunculate; peduncles glabrous, 20-40 mm. Involucre hemispherical to campaniform, 3.0-5.0 x 3.0-10 mm, 1-seriate, bracts broadly ovate to broadly elliptic, 2.3-3.0 x 1.0-2.5 mm, glabrous, green, apex and margins narrowly scarious, three to five veined, secondary venation prominent. Receptacle flat, epalate; pedicels tubiform, 0.3-0.6 mm long, decreasing in length centrifugally, attaching to floret apically. Disciform florets female, 3 to 10, in single outer series; corolla absent; style 0.7-0.8 mm long; ovary marginally ribbed, glabrous on inner face; 2 apical appendages present. Disc florets bisexual, 25 to 40; corolla 1.5-2.0 mm long, yellow, funnel-shaped tube with basal swelling, longitudinal resin canals present, limb slightly wider than tube, 4 lobed; lobes triangular, upright to spreading, dorsally tuburculate, glandular; anthers 0.5-1.2 mm long (including apical appendages), ecaudate, apical appendages ovate, acute; style terete with thickened base; branches truncate, papillate apically-dorsally; ovary marginally ribbed, glabrous. Cypselas heteromorphic; disciform cypselas ovoid, ca. 1.5 x 0.6 mm, marginally ribbed, with two ovate apical appendages, glabrous; disc cypselas not seen.