(nat) Spiny amaranth, pakai kuku
Monoecious annual herbs; stems sometimes tinged with red, erect, sometimes ascending, 4-15 dm long, usually branched, striate, glabrous or pubescent with multicellular hairs, especially above, most leaf axils with a pair of divergent spines up to cm long. Leaves ovate to rhombic- ovate, elliptic, lanceolate-oblong, or lanceolate, blades 1-12 cm long, 0.8-6 cm wide, glabrous, lower surface occasionally sparsely pilose, especially along the veins, petioles 1-9 cm long. Flowers green, in axillary clusters in the lower part of the plant and in unbranched or branched spikes in the upper part, the lower clusters entirely pistillate as are the lower flowers of the spikes, the upper flowers in the spikes staminate, bracts and bracteoles deltate-ovate, membranous, tipped with a pale or reddish awn; sepals 5, those of staminate flowers broadly lanceolate or lanceolate- oblong, apex acute or acuminate, those of pistillate flowers narrowly oblong or spatulate-oblong, 1.5-2.5 mm long, apex obtuse or acute, mucronulate; stigmas (2)3. Fruit ovoid, with a short inflated neck below the style base, ca. 1.5 mm long, regularly or irregularly circumscissile, rarely indehiscent, the upper part rugulose below the neck. Seeds black, shiny, compressed, 0.8-1 mm long, inconspicuously reticulate. [2n = 32, 34.] Widespread in warmer regions worldwide, perhaps of American origin; in Hawaii naturalized and often common in low elevation, disturbed sites on Kure Atoll and documented from all of the main islands except Niihau and Lanai. Naturalized prior to 1928 (Neal & Metzger, 1928). —Plate 4.