The galapagos islands map of the galapagos islands

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Plant life

As else where on our planet green plants form the base of the food chain and are the basis of all life on and around the Galapagos Islands. Of the approximately 500 species of "higher" plants found on these islands today about 40% are endemic. These plants combined with the 300 species of introduced plants and 500 species of mosses, lichens and liverworts give the Galapagos its complex ecosystem.

The island's flora is found in several specific life zones and an understanding these zones helps with the identification and appreciation of the wildlife found here. From the Mangrove Swamps that cover the wet coastal zone and the Prickly Pear Cactus of the Arid Lowlands to the Scalesia Trees and Miconia of the higher Humid Zones the Galapagos hosts an interesting array of flora.

Life Zones

The climate on the islands runs a gradient from the dry low lying areas along the coast to the high moist areas near the volcano tops. In total 7 life zones have been described within the archipelago.

Various plants and animals have adapted over the years to the conditions of the islands and in some cases the specific conditions of the zone in which they are found. Many plants are restricted, in their distribution, to a specific zone, and the animals that dependent on those plants can be found there as well. Depending on the conditions, some birds and animals migrate between zones.

Coastal Zone

The lowest life zone on the island is the coastal zone and the plants that exist on the seas edge can be divided into two sub-groups, the Wet Coastal Zone or Mangrove Zone and the Dry Coastal Zone or Beaches and High Tide Areas.

Mangroves live in the Wet Coastal Zone. These salt-tolerant trees and shrubs thrive in shallow and muddy salt or brackish waters. In the Galapagos there are 4 species of Mangroves including the Black Mangrove, White Mangrove, Red Mangrove, and Button Mangrove.

The Dry Coastal Zone is made up of the dry sandy area from the sea to the high water line. This area supports low lying spreading plants which are able to retain water in their leaves and stems. One of the most conspicuous of these plants is the Sesuvian portulacastrum a herb whose stems turn a bright reddish color during the dry season.

Arid Lowlands Zone

As an island slopes from the beach to an elevation of about 197 ft (60 m) elevation an arid desert like zone occurs. This region is home to the many Cactus that live in the Galapagos including the Prickly Pear Cactus, Lava Cactus and Candelabra Cactus. The endemic lava morning glory and passionflower are vines that can also be found in the Arid Lowlands. The silvery leafed Palo Santo Tree with its collection of lichens grows near the upper portion of the Arid Lowlands Zone.

Transitional Zone

Plants characteristic of both the Arid Lowlands and the Upper Moist Zones are found in the Transition Zone. This zone is home to a variety of small trees and shrubs including the endemic Pega Pega Tree and the Guaybillo, which produces a small white flower that develops into a fruit similar to its cousin the Guava. The Galapagos Tomato, endemic to the islands is a salt resistant tomato that has been used to create a hybrid capable of growing in salty soil around the world.

Scalesia Zone

The lowest of the "humid" zones this zone is named for the daisy tree that grows at altitudes of between 970 &1970 ft (300 - 600 m) elevation. The Scalesia is one of the few trees in the Aster Family and grows to heights of 16 - 50 ft (5-15 m). Its trunk and branches are covered with moss and lichens. This area is humid and has the feel of a cloud forest.

Since humans arrived in the islands the number of Scalesia Trees has been greatly reduced. Introduced pigs and goats devour the young plants. People also introduced the Guava, a plant whose dense growth patterns steals nutrients and eventually makes it impossible for the competing native plants to survive.

Miconia Zone

Above the Scalesia Zone at 1950 - 2300 ft (600-700 m) is a humid zone named for the Miconia shrub that once dominated this region. Miconia robinsoniana grows to heights of 10-13 ft (3-4 m) and is easily identified by its yellow or reddish shaded leaf margins. Miconia are endemic to the Galapagos, but since the arrival of man it has become the most endangered plant in the islands. Introduced cattle have grazed it to dangerously low levels.

Pampa Zone

The highest vegetation zone in the Galapagos is found on those islands with elevations of more than 3000 ft (900 m). This is the Fern-Sedge or Pampa Zone. The appearance of this zone depends on the amount of moisture it receives. This region contains no true trees or shrubs but the tall Galapagos Tree Fern and several Liverworts are commonly found here.

Galapagos Cactus

Cacti are the most common plants of the dry inland portions of the Galapagos Islands. These succulents are able to store water in their stems and leaves and survive in hostile climates and during times of drought. Most cacti have spines, which have evolved from leaves. These are a fundamental part of the Cacti, important as a guard against grazing animals and providing shade to help keep the internal temperature of the plant down. Spines also channel any rainwater towards the base of the plant. The waxy coating that covers the skin of the cactus, known as the glaucus bloom, reduces evaporation by the plant by holding in moisture. Leaf like stems known as pads store and conserve moisture and work as photosynthetic organs for the cacti.

Endemic cacti in the Galapagos include the Lava Cactus, Candelabra Cactus, and the species of Opuntia (Prickly Pear) found in the Galapagos.

Prickly Pear Cactus (Opuntia Cactaceae)

Native to the tropical and subtropical regions of the United States, Baja California and the Sonora Desert region of Mexico the prickly pear has been transplanted by humans all over the world and is now thought by many botanists to be the most widely distributed plant on earth.

An endemic species of Opuntia cactus is the most common cacti on the islands. It grows like a shrub except on those islands where herbivores are a threat and here the trunks can grow up to 5 ft tall. The prickly pear cactus is the staple in the diet of land iguanas & tortoises'. The yellow flowers develop into an orange-red thorn covered fruit.

Several different varieties of prickly pear cactus have developed on in the Galapagos. These range in size and shape from the Opuntia echios variation gigantea which may grow to 40 ft. (12 m) in height to the Opuntia echios variation barringtonensis found on Santa Cruz whose trunk can measure 4 ft. (1.25 m) in diameter. These Galapagos Cacti provide habitat and a source of food source for many of the birds and animals on the islands including two species of Finch, Iguanas, Doves, Tortoises and Mockingbirds.

Lava Cactus (Brachycereus nesioticus)

Found in lava the fields, as their name suggests, these small cactus grow in clumps measuring up to 23 in (60 cm) in height. New growth on the cacti is yellow but as the cacti matures the color fades, becoming paler and eventually turns to a gray or black color with age. The creamy white flowers are visible in the early morning hours but have usually faded by 8 AM.

Candelabra Cactus (Jasminocereus thouarsii)

Named for its shape this large endemic cactus grows to heights of 23 ft (7m). Its tube shaped pads resembles the Organ Pipe Cactus of the Sonora Desert. The1 - 2 inches (2-6 cm) long green or red flowers open before dawn and develop into fruits of the same colors. The Candelabra Cactus can be seen on the cliffs outside Puerto Ayora on Santa Cruz.

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