GALAPAGOS CACTUS

In the dry inland portions of the Galapagos Islands the most common plant is the cactus. These succulents, able to store water in their stems and leaves, thrive in hostile climates and during times of drought. Most members of the cactus family have spines, which have evolved from leaves. The spines are a fundamental part of the cactus, used to guard against grazing animals making the plant difficult to chew, offer shade keeping the internal temperature of the plant down, and it channels 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 works as photosynthetic organs for the cactus.

Endemic cacti in the Galapagos include the lava cactus, candelabra cactus, and the species of opuntia (prickly pear) found in the Galapagos.

Opuntia Cactus - Prickly Pear Cactus (Opuntia cactaceae)

Prickly Pear Cactus is the common name for plants of the cactus family. Native to the tropical and subtropical regions of the United States, Baja California and the Sonora Desert region of Mexico these plants have spread out throughout the world's tropical regions.

In Galapagos there are 6 different species of the Opuntia Cactus (O. echios, O. galapageia, O. Helleri, O. insularis, O. saxicola, O. megasperma), which can be divided into 14 different varieties.  These cactus range from the opuntia echios variation gigantea which grows to 40 ft. (12 m) in height to the opuntia echios variation barringtonensis found on Santa Cruz whose truck measures 4 ft. (1.25 m) in diameter.

The opuntia is the most common cactus in the islands. Identified by the flat and rounded cladodes (cactus pad) which can been seen with two different types of spines and yellow flowers. On many islands the opuntia appears as a shrub, except on islands where herbivores are a threat then the opuntia can be found with trunks growing up to 5 ft tall. Opuntia Cactus are considered an excellent example of adaptive radiation. These cactus provide the habitat and food source for many of the birds and animals on the islands including 2 species of finch, iguanas, doves, tortoises and mockingbirds.

Lava Cactus (Brachycereus nesioticus)

Lava Cactus are a pioneer plant growing (as their name suggests) in lava fields. These small cactus grow in clumps measuring up to 23 in (60 cm) in height with soft furry spines. New growth on the cacti is yellow as the cacti mature the color fades becoming paler and eventually becomes a gray or black color with age. The creamy white flowers are visible in the early morning hours only, and have normally faded by 8 in the morning.

Candelabra Cactus (Jasminocereus thouarsii)

The large Candelabra Cactus is named for its shape. Endemic to the Galapagos Islands these cactus grow to a height up to 23 ft (7 m). Growing in the arid zones its tube shaped pads resembles the organ pipe cactus of the Sonora Desert. The green or red flowers are 1 - 2 inches (2-6 cm) that open before dawn; develop into fruit of the same colors. The candelabra cactus can be seen on the cliffs outside Puerto Ayora on Santa Cruz.