Opuntia echios Opuntia echios Opuntia echios is a species of plant in the Cactaceae family. It is endemic to the Galápagos Islands (Ecuador) and is commonly known as the Galápagos prickly pear, but there are five other species of prickly pears that also are endemic to the archipelago ("O. galapageia", "O. helleri", "O. insularis", "O. megasperma" and "O. saxicola"). There are five varieties of "Opuntia echios", each with a different appearance and distribution: "Opuntia echios" var. "echios" on the islands of Santa Cruz, Baltra, Daphne Major and South Plaza, "Opuntia echios" var. "barringtonensis" on Santa Fe, "Opuntia echios" var. "gigantea" near Academy
Opuntia arenaria 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 4-7 x 2–3 cm in size. Major spines are found in the distal areoles and are often reflexed, up to 30 mm long. Minor spines are