The main factor that ties these plants together are their very large, showy flowers. These flowers are all very similar in structure – funnel shaped, with hairy/wooly scaled floral tubes which give rise to hairy, globular fruit filled with a soft, mushy pulp. The flowers seldom last more than a single day and may be diurnal or nocturnal depending on the species. These species hybridize easily and have resulted in a tremendous number of hybrids that some cactus growers specialize in or grow exclusively. There are certainly enough hybrids to keep even ardent hobbyists busy.