Arid conditions prevail in the Galapagos Islands archipelago and in the Galapagos dry area, it is common to find drought-resistant dry area flora. Much of the landscape is harsh and dominated by this type of vegetation. On many Islands, you will only find a dry zone and a coastal zone.
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 cacti have spines, which have evolved from leaves. The spines are a fundamental part of the Cacti, 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 glaucous 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 cacti.
Endemic cacti in the Galapagos Islands include the Lava Cactus, Candelabra Cactus, and the species of Opuntia (Prickly Pair) found in the Galapagos.
Prickly Pear Cactus is the common name for plants of the Galapagos Princkly Pair Cactus (Opuntia Cactaceae) 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.
Besides being an endemic cactus it is also the most common cacti in the islands. With its yellow flowers it grows like a shrub, except on islands where herbivores are a threat then trunks can grow to 5 ft tall. The Prickly Pair Cactus is the staple of the Land Iguanas & Tortoises‘ diet. Their flat jointed stems covered with small stiff hairs and spines identify the cacti. The yellow flowers develop into an orange-red thorn-covered fruit.
The Prickly Pair has developed into 14 separate types ranging 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.
Growing in lava 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 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.
Named for its shape, this large endemic cactus grows to heights of 23 ft (7m). Its tube-shaped pads resemble the Organ Pipe Cactus of the Sonora Desert. The green or red flowers are 1 – 2 inches (2-6 cm), which 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.