Annual herbs; leaves petiolate, opposite, orbicular to ovate, entire, acute or acuminate, pubescent, tomentose or velvety rarely glabrous; flowers small, white, flowers bisexual, solitary in axil of bract in terminal, more or less slender spikes, usually with a robust rachis that rapidly lengthens up to 30 cm long; bracts lanceolate, membranous, glabrous, bracteoles spinous with short, membranous wings at base; tepals 4-5, narrowly lanceolate, aristate, shining, strongly ribbed; stamens 5, anthers 2-celled, filaments filiform, connate at the base, alternate with fimbriate, pseudostaminodes; ovary 1-celled, oblong, sub compressed with solitary, pendulous ovule from a long basal funicle style slender, stigma truncate-capitate; utricle, ovoid, indehiscent, 1-seeded, falling off with bracteoles and tepals; seeds oblong, smooth.