Opuntia humifusa late spring. The juicy and edible red fruits measure from 3–5 cm. As the fruit matures, it changes colour from green to red, and often remains on the cactus until the following spring. There are 6 to 33 small, flat, light-colored seeds in each fruit. This species was originally native to arid areas of Montana southward to New Mexico, and eastward to the lower Great Lakes, and along the East Coast from the Florida Keys to coastal Connecticut. Some botanists treat this cactus as a variety of "Opuntia compressa": hence "Opuntia compressa" var. "humifusa", or a synonym of "Opuntia compressa".
Opuntia arenaria strongly deflexed and much shorter. Overall, plants (clumps) of cladodes may be 20–30 cm across and about 4–8 cm tall. Fruits are small, about 2.5 cm. Opuntia arenaria Opuntia arenaria was considered a variety of "O. polyacantha" by many botanists, and is still treated that way in the Flora of North America. However, "O. arenaria" is diploid and "O. polyacantha" is tetraploid. It was described by Engelmann in 1856. "Opuntia arenaria" can grow in soil that is essentially pure sand. It has rhizomes up to 1.5 m long that give rise to above ground shoots with small cladodes that are