On the whole, Galapagos plants tend to be 'pioneer' species, hardy plants which successfully cross oceans and manage to establish themselves in the often hostile environment of islands. Because relatively few plants succeed in doing this, the flora is 'depauperate' - there are far fewer species here than in similar environments on the South American mainland. Plants are also adapted to having very few insects or other animals to pollinate their flowers or disperse their fruits and seeds. This means there are few big, showy flowers to attract pollinators and few specialized fleshy fruits. But there are some fascinating relationships between plants and animals. The giant tortoises and land iguanas, for example, feed on Opuntia, the prickly pear cactus, and have influenced its growth form on different islands.
There are about 560 native species of plants in the islands, in other words, plants which arrived in the islands by natural means. Of these, almost one third are endemic to the islands, meaning they are found nowhere else on earth. For example, Galapagos has its very own, endemic species of cotton, pepper, guava, passion flower and tomato. Not only that but many species are so different from others elsewhere that they are grouped in their own endemic genera.