Manual of the New Zealand Flora.
1. Alternanthera, Forsk
1. Alternanthera, Forsk.
Annual or perennial herbs, usually prostrate or decumbent, rarely erect, glabrous or more or less pubescent or tomentose. Leaves opposite. Flowers small, whitish, capitate; heads sessile in the axils of the leaves, often clustered. Perianth 5-partite; segments unequal, the anterior and 2 posterior flattened, the 2 lateral innermost, concave. Stamens 2–5; filaments short, connate at the base into a membranous cup, with or without intervening stami-nodia; anthers 1-celled. Ovary orbicular or obovoid; style short or almost wanting; stigma capitellate or rarely 2-fid; ovule solitary, pendulous from an elongated basal funicle. Utricle compressed, ovoid or orbicular or obcordate; margins often thickened or winged. Seed vertical, lenticular; testa coriaceous.
A small genus of 16 or 18 species, mainly tropical or subtropical, most abundant in America. The New Zealand species is a common weed in warm countries.
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1. A. sessilis, R. Br. Prodr. 417.—A prostrate or decumbent herb. Stems numerous from the root, branched, creeping and rooting, sometimes ascending at the tips, 4–18 in. long, glabrous or with 2 opposite pubescent lines. Leaves variable in size,½–3 in. long, linear-lanceolate to linear-oblong or oblong-obovate, obtuse or acute, narrowed to the base, entire or obscurely denticulate, glabrous or pubescent in the axils. Flowers aggregated in dense axillary clusters ¼–⅓ in. diam. minute, whitish, about 1/12 in. long. Perianth-segments glabrous, rigid, acute. Stamens 2–3. Utricle broadly obcordate, with broad corky wings.— Hook. f. Fl. Nov. Zel. i. 212; Handb. N.Z. Fl. 234. A. denticulata, R. Br. Prodr. 417; A. Cunn. Precur. n. 367; Raoul, Choix, 43; Benth. Fl. Austral. v. 249.
North Island: Marshy places from the North Cape southwards to Rotorua and Hawke's Bay, rare and local to the south of Auckland. Sea-level to 1000 ft.