Cacti on Galapagos - the amazing flora

The prickly pear cactus, also known as the tree opuntia, is found all over the world and is also the most common cactus on the Galapagos Islands. It grows in the dry and transitional zones of most islands. The subspecies megasperma (giant opuntia) and echio are common on the Galapagos. The giant opuntia subspecies on Española is considered endangered, which is probably due to the introduction of goats and the decline of giant tortoises there. The largest opuntias reach up to 12m in height and grow up to 1m thick. The trunks are covered with stiff little hairs and spines and the species has flowers that later develop into small orange-red fruits covered with thorns. Its flat, cushion-like leaves (cladodes) and juicy fruits are an amazing adaptation to the aridity of the islands. The fruits serve as food and habitat for many animal species, including Darwin’s finches, land iguanas and giant tortoises.

One of the ways in which opuntias are spread on the Galapagos is by rice rats. After they have eaten the fruit, their seed shells are damaged by the rats’ gastric juices, which facilitates germination. If the seeds hit the ground again after being excreted, they can form roots more easily.