Opuntia is a genus in the cactus family Cactaceae. The name Opuntia comes from the name of a Greek city. Both prickly pears (padded types) and chollas (cylindrical types) are included in this genus of about 300 species. Opuntia is a very large genus, varying in size from 2 inches tall miniature plants to 100 feet tall trees. They are native from Canada, to Chile and Argentina. Opuntias are an easy group of cacti to grow. They grow in sections, any of which can be removed and rooted to start a new plant. The pads are actually modified branches or stems that serve several functions: water storage, photosynthesis and flower production. But members of the Opuntia genus are unique because of their clusters of fine, tiny, barbed spines called glochids. Found just above the cluster of regular spines, glochids are yellow or red in color and detach easily from the pads. Opuntias often have large, colorful flowers. The fruits of most prickly pears are edible and sold in stores under the name "tuna." Prickly pear branches (the pads) are also cooked and eaten as a vegetable. They too are sold in stores under the name "Nopalito." Hardiness zones 9-11, (-5øC/25øF, 4øC/40øF). In the spring and summer the soil should become fairly dry between waterings. The plant should be given a deep drink at this time, to the extent that the water runs out the bottom of the pot. In winter, it is best to water only enough to keep the plants from shriveling. Opuntia grow best where they receive at least 4 hours of sunlight daily, but they will grow fairly well in bright indirect light indoors. In the spring and summer, Opuntias prefer night temperatures of 65øF to 70øF and daytime temperatures of 75øF to 85øF. Use a normal cactus soil.