Characteristic features of opuntia basilaris
are the complete absence of spines and the grey-blue color of the pads, which as the common name suggests, are shaped like the tail of a beaver. The plant forms low clumps, spreading sideways rather than upwards, and does not develop a woody central trunk. Pads are covered by fine velvety hairs in addition to the neat rows of glochids, and take on a purple tinge during arid conditions, when the surface can become shriveled. The cactus grows over a wide range of habitats, from hot deserts along the lower Colorado River to mountain slopes in south Utah.