Astrophytum ornatum var. mirbelii Family: Cactaceae. A close relative of the Bishop's Cap cactus (A. myriostigma). The plant is strongly ribbed and covered with fairly dense white felt. This denser white coloring is what separates var. mirbelii from the normal form of the species. Unlike the Bishop's Cap this species forms numerous yellow spines. For several years the plant will grow bigger in a globular form, but will eventually become upright. Very old specimens can reach 6' or more. Don't worry if you have limited space, it can live in a 6" pots for many, many years (upwards of 10 years or more). Flowers bright yellow and produced throughout the summer. Easy to grow, just give normal cactus care. Protect from frost.