Amaranthus spinosus
Content
Description
Annual, monoecious or polygamo-monoecious, robust, glabrous herb to 1.5(-2) m; stems slightly woody at base, striate, green, pink or red; rigid stipular spines to 2.5 cm long, axillary, paired, spreading to slightly recurved. Petiole to 6(-8) cm long, about as long as blade; blade ovate to elliptical or rhombic, to 11 x 5 cm, undulate. Inflorescence of axillary clusters, 5-15 mm wide, terminallinear spikes or panicles to ca. 14 cm long; bracts lanceolate to subulate, 1-5 mm long, shorter than or only very slightly exceeding perianth, sometimes subspinose. Flowers green, white or brown, hyaline, midvein green. Male flowers usually at or near apex of terminal portion of inflorescence; tepals 5, lanceolate or oblong, 2.1 x 1.0 mm, acute, apiculate(outer 2 tepals mucronulate); stamens 5, anthers linear, to 2.3 mm long, apiculate. Female flowers more numerous than male flowers; tepals 5, lanceolate, oblong to elliptical, 1.5-2.5 x 1 mm, apex acute to retuse, mucronulate; stigmas 2-3, usually spreading. Utricle irregularly dehiscent or circumscissile, ovoid-conical, smooth or somewhat puckered below; seed lenticular, 0.7-1.1 mm wide, black or (reddish-)brown, lustrous.