Gymnocalycius sp. Cactaceae Tina Saravia, Sunset District, San Francisco (indoors) This genus of cactus is a wonderful group of plants for the window sill gardener. They are forgiving plants that tolerate very little water, although they don't mind regular water. They are almost all small and have pale pink flowers. This particular species has darker pink flowers than most. The grafted pink and red-bodied cactus available commonly at nurseries are also in this genus. Most members of the genus are under 3 inches wide at 20 years old. Most are native to Argentina and can be grown outdoors if kept dry in the wintertime. Photo by Bruce Peters