I took this photo of one of our favorite specimens, the Bishop’s Cap. We purchased this cactus in a three-inch plastic cup about nine years ago while on vacation near Phoenix, AZ. Today, it measures over twice as wide and tall. This cactus has given us dozens of these pretty flowers over the years we’ve had it.
Click on the image for a larger view.
More from WikiPedia.
Astrophytum myriostigma
Common names: Bishop’s Cap Cactus, Bishop’s Hat or Bishop’s Miter Cactus. This is a species of cactus native to the highlands of northeastern and central Mexico.
Bishop’s Cap is a spineless cactus defined by the presence of three to seven (usually five) pronounced vertical ribs which define the cactus’ shape when young (the genus name “astrophytum”, literally, “star plant”, is derived from the resulting star-like shape). As the cactus ages, more ribs may be added and it becomes more cylindrical in shape, growing up to about 70-100 cm tall and 10-20 cm in diameter. The stem is often covered with whitish flecks.
The cactus flowers in the spring or summer with one or more waxy flowers 4-6 cm diameter near its apex; the numerous petals are yellow, sometimes with an orange or red base. Pollinated flowers develop into a hairy reddish fruit about 2-2.5 cm in diameter. Plants may take up to six years to flower. It is commonly grown as an ornamental plant in cactus collections.
While we were in the back yard this afternoon, I took some photos of all the nice flowers and plants. This tiny flower on this ‘Old Lady’ cactus surprised me. I saw some tiny buds earlier in the day and thought they might grow in size and someday produce some nice flowers. This one opened up and is only about a quarter inch in diameter. I think its cute. 
