Erect, succulent shrub; several shoots arising from the root, stem tall, columnar, sharply 3-4 or 6-ridged or winged, arioles echinate, covered with clusters of sharp spines; leaves reduced to scales, areoles with felted hairs and more or less, numerous prickles; flowers solitary, from the older areoles, large, sessile, bisexual, funnel shaped, white, zygomorphic, with many, unequal, spirally arranged tepals, of these outer or lowest often clothed the hypanthium outside the ovary, the median calyciform and the inner petaloid; calyx tube adnate to ovary, lobes 3-many; petals many, free or shortly united at the base, imbricate; stamens numerous, free, adnate, included or a little exserted from the hypanthium with long filaments; ovary 1-celled, style filiform or cylindric, stigma with 2-many rays, ovules many on parietal placenta; fruit succulent berry, 1-celled with pulpy placentas; seeds many, oblong or reniform, smooth or tubercled.