This genus belongs to the most favoured amongst cactus enthusiasts. People love them for being so diverse, so flowery and so easy to grow. They dwell in Mexico and the south of USA. The smallest one, A. asterias, reaches (rarely) maximum 15 cm in diameter and half of it in height and on the other hand the biggest, A. ornatum, happens to be 30 cm across and 2 m high! A. asterias and A. myriostigma do not have any spines whereas A. capricorne is covered with very dense and long but not prickly spination (A. ornatum can cut you skin easily with its spines though). Flowers are big, usually yellow with red centre. In collection they would appreciate some limestone in the potting mix and normal (as for cacti, of course) watering along with high temperature and not shaded sun.