Galapagos Islands

The plants of the Galapagos Islands had a great influence on Charles Darwin's work. His interest in plant geography and dispersal mechanisms was closely tied to the results of his collections on the islands. The first scientific guide to the flora of the archipelago was prepared by Joseph Dalton Hooker (1846), an eminent botanist, and was based mostly on Darwin's specimens. Plants are the basis of all life within the Galapagos Islands. Of the 500 species of "higher" plants 40% are endemic. These plants combined with the 200 species of introduced plants and 500 species of mosses, lichens and liverworts give the Galapagos its complex ecosystem. The variety of plants on the islands is quite large since they all have different climates. The mix between lava rocks, deserts and forests is quite interesting and shows many different kinds of environments to expore for vegetation.

The coastal strip of the Galapagos is mainly evergreen. This zone is not strictly a climatic vegetation type but is an ecological one based on salt tolerance abilities of certain species at the land/sea interface. The type of vegetation found varies greatly and depends on the type of coast. Many plants in this zone are adapted to dispersal by the sea, especially the mangroves. Few plants found in this zone are endemic as a result of the unstable nature of the environment.

Lava Cactus: One of the first plants to colonize a new lava field, the Lava Cactus is found on barren black lava flows such as this one on Bartolome Island. It seems to have no food value even to the lizards, although its large white flowers may offer food for the carpenter bee and other insects.

Espino:  The espino, or spiny bush grows on inhospitable-looking beaches. In the hot sun its few leaves are curled up and inconspicuous. This one grew to about six or seven feet high on the beach on Bartolome. It produces a sour red or brown fruit edible to both finches and humans.

Cacaotillo:  The cacaotillo (Miconia robinsoniana) grows only on the southern slopes of the two islands of Santa Cruz and San Cristobal, at about 500 to 700 meters elevation. In the Miconia vegetation zone the cacaotillo shrub is the tallest plant, reaching about 2 to 5 meters high. It is endemic to the Galapagos.

Passion Flower: This species of passion flower is endemic to the islands and the commonest of the three species. It occurs from the arid zone up to the Scalesia zone. (Learn more about vegetation zones.) It is a vine, climbing over the ground, shrubs and tree trunks. When ripe, the fruits, protected in feathery bracts, turn yellowish. Birds eat them, dispersing the seeds. The flowers are white, unlike most passion flowers (on the mainland) which are red to purple. This picture was taken at Punta Cormorante on Floreana Island.

Opuntia: The genus Opuntia is represented in Galapagos by six species and fourteen endemic varieties. O. megasperma var. orientalis of Española Island is listed as an "endangered" species, due to decline caused by introduced goats until their eradication in 1978 and by the dramatic decrease in the giant tortoise, which dispersed Opuntia seeds. Today this species shows restricted distribution and poor regeneration.

 Darwin Research Station
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