The Flora of the Galapagos Islands is remarkably diverse, forming the foundation of all life within this unique ecosystem. The islands are home to approximately 560 native species of “higher” plants, which arrived through natural means. Impressively, about a third of these species are endemic, found nowhere else in the world, making the plant life of Galapagos as extraordinary as its wildlife.
Among these endemic plants is the notable Scalesia, commonly known as the “daisy tree.” Scalesia has evolved into numerous species, mirroring the adaptive radiation observed in Darwin’s finches. These unique plants, alongside 200 species of introduced plants and 500 species of mosses, lichens, and liverworts, create a rich and complex ecosystem.
Vegetation Zones in the Galapagos Islands
The Galapagos Islands’ plant life is organized into distinct vegetation zones, each supporting different species and contributing to the overall biodiversity. This intricate ecosystem highlights the ecological significance of the islands’ flora, emphasizing the need for its conservation and study.
Coastal Zone of the Galapagos Islands
The Coastal Zone is the lowest life zone on the Galapagos Islands, characterized by its evergreen nature and salt-tolerant species at the land/sea interface. This zone is divided into the Humid Coastal Zone or Mangrove Zone and the Dry Coastal Zone. Salt-tolerant mangroves form forests in coves and shallow salt waters, including four varieties: Black Mangrove, White Mangrove, Red Mangrove, and Button Mangrove. In the dry coastal zone, creepers, grasses, and shrubs dominate, with many plants adapted to sea dispersal. This zone has fewer endemic species due to the unstable environment and high immigration rates.
Dry Zone
The Dry Zone is the most extensive vegetation zone, extending from the beach to about 197 feet (60 meters). It features a semi-desert forest dominated by deciduous trees and shrubs, home to many Galapagos cacti such as nopal, lava cactus, and candelabra cactus. Plants in this zone have adaptations to withstand drought, and there are many endemic species. Lichens are abundant, absorbing moisture from the occasional Garúa fogs.
Transition Zone
The Transition Zone has characteristics intermediate between the Scalesia and Dry zones. It is dominated by species distinct from those in adjacent zones, though plants from both zones are present. This zone features a denser and more diverse deciduous forest compared to the arid zones, making it difficult to identify dominant species.
Scalesia Zone
The evergreen Scalesia Zone, a lush cloud forest, is dominated by Scalesia pedunculata trees. This zone, found only on the higher islands, is rich in soil fertility and productivity. It has been extensively logged for agriculture and livestock. The Scalesia forest is diverse, with many endemic species.
Brown Zone
The Brown Zone, an open forest between the dense Scalesia forest and shrubby Miconia vegetation, is dominated by cat’s claw, tournefortia pubescens, and aunistus ellipticus. Trees in this zone are covered with epiphytes, mosses, liverworts, and ferns, giving it a brown appearance during the dry season. This zone has largely disappeared due to human colonization.
Miconia Zone
The humid Miconia Zone, located between 1950 and 2300 feet (600-700 meters), is named after the Miconia shrub that once dominated this region. The southern slopes of San Cristóbal and Santa Cruz are the only places where a dense shrub belt of the endemic Miconia Robinsoniana exists. This area lacks native trees but is abundant in ferns and liverworts.
Pampeana Zone
The Pampeana Zone, the highest vegetation zone on islands with elevations above 3000 feet (900 meters), consists mainly of ferns, grasses, and sedges. This is the wettest zone, especially during the Garúa season, with up to 2500 mm of rain in some years.
Endemic Species of the Galapagos Islands
Darwin’s Cotton (Gossypium darwinii): Also known as Galapagos cotton, this endemic cotton plant is found only in the Galapagos Islands. Growing up to 3 meters tall, it is easily identified by its large bright yellow flowers with a violet center. The seeds produce white cotton used by birds for nest building. Darwin’s Cotton is best seen on Floreana, Isabela, San Cristobal, and Santa Cruz islands. Genetic studies suggest it is closely related to native American species, likely arriving from South America via wind, bird droppings, or sea debris.
Lava Cactus (Brachycereus nesioticus)
The Lava Cactus, endemic to the Galapagos Islands, is the only species of its genus. This cactus is a pioneer of lava fields, featuring soft, hairy spines and growing in clumps up to two feet tall. New growth is yellow, aging to brown and eventually gray. The cactus produces creamy white flowers visible only in the early morning, often wilting by 8 am. Its dark brown fruits, up to 3.5 cm long, are covered with yellow spines. Best viewed on Santiago, Bartolome, Isabela, Fernandina, Genovesa, and Chinese Hat Islet.
Darwin’s Daisy (Lecocarpus pinnatifidus)
The cut-leaf daisy, named for its deeply lobed leaves, is an endemic, rare plant of the Galapagos. This small evergreen shrub, up to 2 meters tall, primarily grows on bare lava or ash. With a bushy head of yellow daisy-like flowers, it is one of the rarest plants globally, found only on Floreana Island. Other endemic species include Darwin’s daisy on San Cristobal Island.
Galapagos Croton (Croton scouleri)
The Galapagos Croton, or “chala,” is an endemic shrub growing up to 6 meters high with gray bark and gray-green leaves. It produces small cream-colored flowers on spikes up to 10 cm long. Its sap can stain clothing dark brown. Found on Santa Fe, Santa Cruz, Genovesa, Santiago, and San Cristobal Island.
Galapagos Nopal (Opuntia cactaceae)
The Galapagos Nopal, or Opuntia, is the most widely distributed cactus on the islands. An example of adaptive radiation, it includes six species and 14 varieties. These cacti range from the giant Opuntia echios, up to 12 meters tall, to the smaller Opuntia echios var. barringtonensis. They provide essential habitat and food for many island species, including finches, iguanas, tortoises, and mockingbirds. Found in the arid and transition zones of most islands.
Candelabra Cactus (Jasminocereus thouarsii)
Named for its shape, the Candelabra Cactus grows up to 23 feet tall with spiny, tube-shaped pads and green or red flowers. Its arms become woody with age, leaving a hollow “skeleton” when it dies. Best seen on Santa Cruz, Sombrero Chino, and Floreana.
Galapagos Lantana (Lantana peduncularis)
This small endemic shrub grows up to 2 meters tall, with white flowers forming compact dome-shaped heads. Found on Santa Cruz, Santa Fe, Española, and Floreana.
Galapagos Purslane (Calandrina galapagosa)
An endangered, arid lowland shrub of the family Portulacaceae, it is only found on San Cristobal (Cerro Colorado). Efforts are underway to cultivate and reintroduce it to its natural habitat. It is a perennial herb with fleshy stems and leaves.
Galapagos Tomato (Lycopersicon cheesmaniae)
An endemic perennial herb found in arid lowlands, transition zones, and Scalesia areas. San Cristobal growers are working to cross it with the common garden tomato to create a flavorful, endemic variety for tourism.
Galapagos Miconia (Miconia robinsoniana)
Found in the southern highlands, it is a large shrub providing excellent nesting habitat for the dusky-rumped petrel. Its foliage ranges from green to dark red, depending on moisture levels. Best seen in the highlands of Santa Cruz and San Cristobal Island.
Galapagos Pega Pega (Pisonia floribunda)
A large, branched tree growing up to 15 meters tall in the Transition Zone, it is often covered with mosses and lichens. The tree produces sticky fruits that aid in dispersal by birds.
Galapagos Guava (Psidium galapageium)
An endemic tree growing up to 10 meters tall with smooth reddish-gray bark. It produces small white flowers and fruits that turn from yellow to reddish brown when ripe. Found in the arid lowlands and humid highlands of several islands.
White-haired Tournefortia (Tournefortia pubescens)
A shrub with whitish hairs on its young branches and the underside of its leaves. It has dark green elliptical leaves and fragrant white flowers. Found in the highlands of Santa Cruz and Isabela.
Darwin’s Fine-leaved Shrub (Darwiniothamnus tenuifolius)
A highly branched shrub growing up to 3 meters tall, found in various habitats. It has narrow leaves and daisy-shaped flowers. The leaves have a pleasant odor when crushed.
Resume
The flora in the Galapagos Islands is remarkably diverse, with a unique array of endemic species that contribute to the archipelago’s extraordinary ecosystem. This flora includes approximately 560 native species of higher plants, about a third of which are endemic, and around 200 introduced plant species, alongside 500 species of mosses, lichens, and liverworts.
Key species include the Lava Cactus (Brachycereus nesioticus), a pioneer of lava fields found on several islands; Darwin’s Daisy (Lecocarpus pinnatifidus), one of the rarest plants globally, known only from Floreana Island; and the Galapagos Croton (Croton scouleri), an endemic shrub notable for its height and sticky sap.
The Galapagos Nopal (Opuntia cactaceae) exemplifies adaptive radiation with several varieties providing essential habitats and food for island wildlife. The towering Candelabra Cactus (Jasminocereus thouarsii) and the small, but distinct, Galapagos Lantana (Lantana peduncularis) further highlight the diversity of plant life.
In addition, endangered species like the Galapagos Purslane (Calandrina galapagosa) and the endemic Galapagos Tomato (Lycopersicon cheesmaniae) underscore the conservation challenges in the region. The Galapagos Miconia (Miconia robinsoniana) and the distinctive Galapagos Guava (Psidium galapageium) are critical components of the islands’ varied habitats.
Overall, the flora in the Galapagos Islands is a testament to the unique evolutionary processes that occur in isolated ecosystems, with each plant species playing a crucial role in maintaining the balance and biodiversity of this natural wonder.
