This genus of perennial cacti habe a ribbed rounded to columnar habit with age. The areoles may or may not have spines and the  lemon-yellow funnel-shaped diurnal flowers appear towards the top of the plant from late spring to summer..

Hardiness zones 10 to 11

Astrophytum species are naturally found in North America growing in Mexico in very well drained, gritty light soils in an open sunny position and are frost tender but drought tolerant. 

The Star Plants are grown for their rounded habit and flowers. They are planted in arid gardens or sunny rockeries as a specimen or used in cacti gardens. They are also used as a potted house plant or a hot house specimen. They are slow growing and establish in 3-4 years and should be watered less during winter. If the temperature falls below 10ºC (50ºF) the plants should be place in glasshouse or protected area. ID 698

Note:
This genus of plants needs protection from wet winters and cold conditions as the plant rots easily in wet soils.

Astrophytum (ass-tro-FY-tum) species

Cactaceae (kak-TAY-see-ee)