Ammannia octandra

de Wilde, W. J. J. O. & Duyfjes, B. E. E., 2014, Ammannia (Lythraceae) in Malesia, Blumea 59 (1), pp. 11-18 : 17

6. Ammannia octandra L.f. — Fig. 3

Ammannia octandra L.f. (1782) 127; Koehne (1903) 50; Backer (1930) 466; (1964) 253; (1973) pl. 441; Soerjani et al. (1987) 342, f. 4.156. — Diplostemon octandra (L.f.) Miq.(1856) 615. — Type: Koenig s.n. (holo BM (typ. cons.); iso C, LINN 156.5), India, Madepala.

Amanella linearis Miq. (1856) 619. — Type: Horsfield s.n. (holo BM; iso K, barcode K000729675 , U).

Erect, annual, glabrous herb, 25–100 cm tall, much-branched; stem 4-angular, not winged. Leaves sessile; lamina glabrous, linear-lanceolate, 3–8 by 0.3–1 cm, base broadly cordate, apex acute, midrib stout, raised beneath. Inflorescences peduncled 2–4-flowered cymes; peduncle 1.5–4 mm long, bracts minute. Flowers 4-merous; pedicel short, c. 0.5 mm long; calyx tube green, glabrous, 4–5 mm long, sharply 4-angled or (nearly) winged, margin often finely serrate, lobes 1–1.5 mm long, ap- pendages minute, acute, curved towards inside; petals 4, red, broadly obovate, 3–4 mm long, caducous; stamens 8, inserted just below halfway in the tube, filaments red, finally exserted, anthers yellow; ovary broadly ellipsoid c. 2 mm long, faintly 4-grooved, style red with green at apex, 4 – 5 mm long, stigma minute. Capsules included within the calyx, c. 5 mm long. Seeds brown-yellow, 0.3–0.4 mm long.

Distribution — India, Thailand; in Malesia: West and East Java.

Habitat & Ecology — In wet paddy fields, at low altitudes. Flowering all year round.

Malesian material examined. JAVA, Backer 5479, 33628, s.n. L0931462; Coert 794;Dorgelo 608;Houwing 22; Kooper 518; Koorders 20883;Unknown s.n. L931459.

Note — Ammannia octandra is not common in Java, but Backer (1964) noted that it is sometimes locally abundant.