A large genus of shrubby and herbaceous plants with composite flowers, abundant in Europe, and especially in the dry, hot regions of western N. America, where they cover great plains and form what is known there as 'sage brush'. Most of them are of a more or less greyish tinge, and are notable for their strong, often agreeable odour. Some half-dozen shrubby species have at times been in cultivation, the two best of which are A. abrotanum and A. tridentata. They need a sunny position, and a well-drained, not rich soil. Increased by cuttings.