Plants are the basis of all life within the Galapagos Islands. With about 560 native species of “higher” plants - plants which arrived in the islands by natural means - in the islands of which about one third are endemic the plant life of Galapagos is just as extraordinary as its wildlife. Many species are so different from others elsewhere that they are grouped in their own endemic genera. These include Scalesia, the endemic 'daisy tree', which has evolved into a whole host of different species in a direct botanical parallel of the Darwin's finches. These plants combined with the 200 species of introduced plants and 500 species of mosses, lichens and liverworts form a complex ecosystem which can be divided into specific vegetation zones:
The lowest life zone on the island is the coastal zone. This evergreen zone is based on salt tolerance abilities of certain species at the land/sea interface. The type of vegetation found varies greatly and can be divided into areas: the Wet Coastal Zone or Mangrove Zone and the Dry Coastal Zone. The salt-tolerant mangroves form forest in coves and in shallow saltwater. In the Galapagos there are 4 varieties of Mangroves including the Black Mangrove, White Mangrove, Red Mangrove and Button Mangrove. In the dry coastal zone, especially on beaches, there are vines, grasses and shrubs. Many plants in this zone are adapted dispersal by the sea and few are endemic because of the unstable nature of the environmental and high immigration rates.
This is the most extensive vegetation zone reaching from the beach to an elevation of about 197 ft (60 m) elevation. It is a semi-desert forest dominated by deciduous trees and shrubs and home to the many Cacti of the Galapagos including the Prickly Pear Cactus, Lava Cactus and Candelabra Cactus as well as vines. The plants have adaptations to withstand drought. There are great numbers of endemic species. Lichens are abundant in this zone because they are capable of absorbing moisture from the occasional Garúa mist.
It is intermediate in character between the Scalesia and Arid zones, but dominated by different species than either of the adjacent zones though plants from both zones occur here too. The forest is still mainly deciduous. It is much more dense and diverse than forest of the arid zones and it is often difficult to say which species is dominant.
The transition zone merges into the evergreen Scalesia zone, which is lush cloud forest, dominated by Scalesia pedunculata trees – thus the zone’s name. This type of forest occurs only on the higher islands and, being the lowest of the humid zones is also the richest zone in terms of soil fertility and productivity. It has been extensively cut down for agricultural and cattle ranching purposes. As typical for a cloud forest, the Scalesia forest is very diverse and has many endemic species.
It is intermediate between the dense Scalesia forest and the Miconia shrub vegetation. It is an open forest dominated by cat's claw, tournefortia pubescens, and aunistus ellipticus. Trees are heavily draped with epiphytes, mosses, liverworts and ferns, which give this zone a brown appearance during the dry season. This zone has disappeared because of colonization by man.
Above the Brown Zone at 1950 - 2300 ft (600-700 m) is this humid zone named for the Miconia shrub that once dominated this region. The southern slopes of San Cristobal and Santa Cruz are the only places where there is a dense shrubby belt of the endemic Miconia Robinsoniana. Native trees are absent from this zone and ferns are abundant in the herb layer. There are also more liverworts than elsewhere.
On the islands with elevations over 3000 ft (900 m) the highest vegetation zone in the Galapagos occurs, the Fern-Sedge Zone or Pampa Zone. There are virtually no trees or shrubs, and the vegetation consists largely of ferns, grasses and sedges. This is the wettest zone, especially during the Garúa season, receiving as much as 2500 mm of rain in some years.
Please find below the description of some of the many endemic plants of the Galapagos Islands:
Darwin's cotton (Gossypium darwinii – also called Galapagos cotton) is an endemic species of cotton plant which is found only on the Galapagos Islands. Darwin´s cotton is a shrub growing up to 3m high easy identified by its bright large yellow flowers with a purple center up to 15 cm long. The oval seeds are up to 3 cm long and break open producing white cotton which is commonly used by birds, especially finches and other small birds, for nest building. The Galapagos Cotton can best be seen on Floreana, Isabela, San Cristobal and Santa Cruz islands. Genetic studies indicate that it is most closely related to native American species thus it is surmised that a seed arrived from South America with the wind, in the droppings of a bird or with debris by sea.
The lava cactus (Brachycereus nesioticus) is a species of cactus and the sole species of the genus Brachycereus. The cactus, is a colonizer of lava fields, hence its common name and endemic to the Galapagos islands. It has soft furry spines and grows in clumps to a height of up to two feet (60 cm). New growth is yellow, turning to brown, which darkens to gray with age. The creamy white flowers are visible in the early morning hours only, shriveling away often as soon as by 8 in the morning. The fruits are dark brown up to 3.5cm long and with yellow spines. The lava cactus can best be seen on Santiago, Batolome, Isabela, Fernandina, Genovesa islands and Sombrero Chino islet.
The endemic cutleaf daisy (Lecocarpus pinnatifidus) is named for the deeply and irregularly lobed margins of its leaves. This small bushy evergreen shrub grows mainly on bare lava or cinder to an height of up to 2m. Usually it has one single stem and a bushy head of leaves and yellow daisy like flowers. It is one of the rarest plants in the Galapagos, and the world, known only from Floreana island. Other endemic species are found on San Cristobal Island: Darwin’s Daisy, Lecocarpus darwinii and on Española: Fitzroy´s Daisy, Lecocarpus lecocarpoides.
The Galapagos croton (croton scouleri - chala) is an endemic shrub of the Archipelago growing up to 6m high. There are four varieties of Galapagos croton. The Galapagos croton has a grey bark, grey-green leaves and round fruits divided into three segments. The small cream colored flowers sit on up to 10cm long spikes. The sap of the croton is well known to stain clothes a dark brown. It can be seen on Santa Fe, Santa Cruz, Genovesa, Santiago and San Cristobal Island.
Prickly Pear Cactus (Opuntia cactaceae) is the common name for the most widely distributed and numerous of the islands cacti. The Opuntia are an excellent example of adaptive radiation with six different species divided into 14 different varieties ranging from the opuntia echios variation gigantea which grows up 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. 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. These Galapagos cactus provide the habitat and food source for many of the birds and animals on the islands including 2 species of finch, doves, land iguanas and tortoises and mockingbirds. The Opuntias can be found throughout the arid zones and transitional zones of most Galapagos islands.
Named for its shape the Candelabra cactus (Jasminocereus thouarsii) is a large endemic cactus that grows to heights of 23 ft (7m). It has tube shaped spiny pads and green or red flowers of 1 - 2 inches (2-6 cm) length that open before dawn and develop into reddish purple globular fruits of ca. 10cm length. The arms become woodier with age and when the plant dies the hollow woody “skeleton” is left behind. The three variations of the candelabra cactus can be seen on several islands, but best on Santa Cruz, Sombrero Chino and Floreana.
Galapagos Lantana (Lantana peduncularis) is an endemic small shrub that grows up to 2m high. White flowers with yellow centers form compact dome shaped heads. The Galapagos lantana can be seen on Santa Cruz, Santa Fe, Española and Floreana islands.
The Galapagos rock purslane (Calandrina galapagosa), an arid lowland shrub of the Portulacaceae family, is only found on San Cristobal (Cerro Colorado) and is considered endangered. At one time it was frequently found at Sappho Cove on the northwest side of this island but it is believed that it no longer exists there. Due to its endangered status there are several cultivation projects to germinate the seeds and return them to their native habitat. The Galapagos rock purslane is a perennial herb which is slightly woody at its base and fleshy in the stems and leaves. To see it, visit the Interpretation Center on San Cristobal Island.
The Galapagos tomato (Lycopersicon cheesmaniae), an endemic perennial herb, is found in the arid lowlands, transition zones, and Scalesia zones. Its many branches are covered with short hairs. The variety found on San Cristobal is the L. cheesmaniae cheesmaniae and like on other islands, is not cultivated. The species of tomato which is cultivated on both San Cristobal and Santa Cruz is the L. esculentum, which is a common garden tomato. Farmers on San Cristobal are now working to crossbreed these two species to create a more flavorful, endemic and organically grown variety to sell to the tourism sector.
The Galapagos Miconia plant (Miconia robinsoniana) is found in the southern highlands of the island where there is sufficient wind and water. It is a large, many branched shrub whose foliage is green to dark red. It changes color from green to red depending on the humidity and grows in dense, almost impenetrable stands above the scalesia zone providing an excellent nesting habitat for the Dark-rumped Petrel. The long slender pointed leaves turn reddish in periods of drought. The flowers have about 4 petals, purplish in color and located at the tips of the branches. The miconia can best be seen in the highlands of Santa Cruz island and on San Cristobal island around the lagoon “El Junco”.
Pega Pega (Pisonia floribunda) is a large many branched tree growing up to 15m height in the Transitional Zone which is usually covered with mosses and lichens. The flowers are in small inconspicuous clusters which produce a sticky fruit which helps their dispersal by birds. The tree owes its Spanish name pega pega (sticky sticky) to these sticky fruits. It is a much braoder tree than most in the zone and is recognizable by its shape as well as its fairly dense foliage. The tree can best be seen in the transitional zone of Santa Cruz Island.
Guayabillo (Psidium galapageium), also known as Galapagos Guava is an easily identifiable endemic tree growing up to 10m height with smooth reddish-grey bark. There are two Psidium species in the Galapagos, but whereas the well-known cultivated guava (P. guajava) is introduced and highly invasive, the Galapagos guava is native to the archipelago and found nowhere else on earth. The Galapagos guava grows as a shrub or a small tree and has simple, elliptic to egg-shaped leaves, and relatively small white flowers. The fruit is a roundish berry that begins yellow but turns reddish brown to black when ripe. There are two varieties of the Galapagos guava, with the slightly larger P. g. galapageium being more common than P. g. howellii. It can be found in the arid lowlands and moist uplands, where it is a common component of the Scalesia zone and can be seen on the islands of San Cristóbal, Santa Cruz, Pinta, Santiago, Fernandina and Isabela.
The White-haired Tournefortia ( Tournefortia pubescens) is a shrub from the Galapagos Islands that owes its name to the whitish hairs that cover its young branches and the lower surface of the leaves. The dark-green leaves have the form of elliptic or egg-shaped blades, while the fragrant inflorescences comprise tightly-packed alternating ranks of small, tubular, five-lobed flowers. The flowers are white with a greenish-yellow throat, and the fruit are small, white and thin fleshed. The shrub grows up to 3m height and can be seen in the highlands of Santa Cruz and Isabela.
The Thin-leafed Darwin’s shrub (Darwiniothamnus tenuifolius) is a much branched shrub that grows up to 3m height. It thrives in a variety of habitats, from lava fields to moist highlands. The up to 10cm long leaves are alternate, usually clustered near the branch tips, narrow pointed and grow very close together. The flowers grow in radiate heads, solitary or in clusters, born near the branch tips and are daisy-like with white petals and yellow stamens. The fruit is ca. 1mm long with numerous hair-like bristles on top, ca. 2mm long. It leaves have a pleasant odor when crushed and its flowers have a mild sweet odor.
The endemic Galapagos passionflower (Passiflora foetida var. galapagensis) is a vine climbing up to 5m height, covering rocks and shrubs. The leaves are up to 10cm long and ivy-shaped. It has long tendrils which wrap around branches or stems of other plants and beautiful white flowers with a purple center. The fruits are up to 3cm long, egg shaped and change their color from green to orange as they ripen. It can be seen in the Scalesia and Miconia zones of Santa Cruz and Floreana as well as on Isabela.
The endemic Santiago Tree Scalesia (Scalesia atractyloides) is only found on Santiago island. The species was believed extinct until five plants were discovered in a crater in 1995 where feral goats couldn't reach them. The crater was surrounded by a fence in late 1997 to keep out the goats and protect the plants. In November 1998, two more adult plants were discovered at another site on Santiago, again on a cliff out of the reach of goats, and the hill on which they were growing was immediately fenced off and it is hoped that the remaining plants will be able to reproduce inside these protected sites.
Floreana Flax (Linum cratericola) is a species that was only discovered in 1968 and was feared to have gone extinct some time after 1981 when it was last seen. Then in April 1997, two scientists from the Charles Darwin Research Station (CDRS) discovered a tiny population of the flax in a volcanic crater on Floreana island. There were just thirteen plants, only eight fully grown, in a tiny area 2m by 1m. In July 1997, the botanists visited again and found that the smaller plants had died leaving only eight, but five new ones were discovered on the cliff above. There are only six plants still alive at the last count but a project began in June 1999 to study these few remaining plants in an attempt to save the species.