Galapagos Islands Plants

How Plants Arrived at the Galapagos Islands

All Galapagos Islands plants came from somewhere else. The islands are really tips of old dead volcanoes jutting up from the ocean's depths. Therefore, they started out as mere rocks rising from the sea. Millions of years ago volcanoes erupted from the ocean's floor, and when they cooled, the lava formed a wall around the eruption center. Then it would happen again and again, each time building the walls higher until finally they rose above the water's surface. Galapagos Islands plants were not possible at all at this point. There was a string of such ocean volcanoes, which formed the archipelago. They were devoid of life until birds, wind and the ocean current brought life to these rocks that would become the Galapagos Islands.

Most of the seeds brought to the Galapagos were brought by birds. Almost two thirds of Galapagos Islands plants arrived via the stomaches and feathers of birds. Wind brought just under a third of the seeds, and the rest arrived by rafting, which means the seeds actually floated on the surface of the ocean.

South American Plants in the Galapagos Islands

Almost every plant on the Galapagos Islands arrived here from South America. A tiny portion of seeds came from Mexico and other parts of Central America. Settlers from the Ecuadorian mainland brought lots of plant seeds from their homes, and by 1986, there were 240 species of plants brought by them. We call these species introduced species. The number of introduced species and the amount of overall plant life is determined by how varied is the topography of each island. If a particular island has more hills and mountains, there will be a greater variety of zones and diverse conditions due to elevation. The larger islands are more likely to have higher hills or mountains and there will be more variety of plant life. In addition, these larger islands will have more soil plus more variance in climate. Diversity is all important in nature, so even a smaller island with more elevation and thus diversity, will have a healthier flora than a larger, flatter island.

Zones of Vegetation

Across the Galapagos Islands we can find seven different vegetation zones. They are:

1. The Littoral Zone
2. The Arid Zone
3. The Transition Zone
4. The Scalesia Zone
5. The Brown Zone
6. The Miconia Zone
7. The Pampa (Fern) Zone

The Littoral Zone

Starting from the ground up, at the lowest zone, we have the Littoral Zone. Salt plays a large role here, so we have mangroves. There are four types of mangroves here, which are:

1. Button Mangrove
2. Red Mangrove
3. White Mangrove
4. Black Mangrove

Besides mangroves with their oval-shaped leaves, there are also saltbrush Cryptocarpus pyriformis. This flat-leafed plant is one of the most ubiquitous Galapagos Islands plants. They get up to six feet tall and the locals call them monte salado. Other species are Sesuvium portulacastrum, which is a succulent and are bright and colorful. Colors are pink or white.

The Arid Zone

Going up in elevation we get the Arid Zone, which actually covers more land area than the Littoral zone. Here we see cacti with very small leaves which are very efficient at photosynthesis. The roots are very deep so as to reach water. Here are some cactus species in the Galapagos Islands:

• Opuntia
• Brachycereus
• The Palo Santo, or Bursera graveolens

The Palo Santo is a tree, actually, that has white bark and in the wet season it has leaves. Also in the Ariz Zone are acacia in shrub sizes. They have small leaves, yellow flowers and tiny fruit. Other plants in the Arid Zone of the Galapagos Islands are:

• Muyuyo (Cordia lutea), a tree with yellow flowers, prevalent at Acaademy Bay on Santa Cruz Island.
• Chala (Croton scouleri), a shrub bearing orange or yellow leaves with grey stalks. The sap stains everything!.
• Manzanillo (Hippomane mancinella), a tree that towers above other species in the Arid Zone. The toxic fruit looks like apples but don't eat!

The Transition Zone

The Transition Zone is above the Arid Zone. Again, we find Palo Santos here, but the pega pega (Pisonia floribunda) is king. The short tree is a home for lichens, which gave the tree its name. Lichens are sticky and Pega pega means "stick stick".

Guayabillo (psidium galapageium) is a spread-out tree with soft and grey bark. The fruit is similar to the guayaba.

The Scalesia Zone, or Humid Zone

This zone has almost constant rain thanks to the garua (wet season). All this humidity means plant life here includes ferns, mosses, and grasses and above all, Scalesia pedunculata. Most people call it lechoso, it's a sunflower tree which can get thirty feet tall. Moss hangs from its branches and its flowers look like small white daisies. Scalesia forests are beautiful. If you go to Santa Cruz you can see one for yourself.

The Brown Zone

Still going up in elevation, we reach the Brown Zone, which also has scalesia trees but without the vibrant moss. Instead of a lovely green, moss falls off and turns brown. Hence the name of the zone. Mostly we see Liverworts which cling to the scalesia trees.

The Miconia Zone

Continuing up, there is the Miconia Zone. It's Miconias are leafy bushes with oval-shaped leaves that look like the leaves of the cacao. The flowers are pink or purple, and the species is found at one thousand meters above sea level. Miconia plant gives its name to the zone, and is found only on Santa Cruz Island and San Cristobal. Miconia is endemic.

The Pampa Zone

This is the top zone, found at the summits of these volcanic islands. Up here it's windy and misty so ferns and grasses do well here. It's wet up here, and there are volcano holes in the ground where you can see ferns growing, quite beautiful. The watery lava tubes also house orchids sometimes. Up here we find only one type of tree, the tree fern (Cyathea weatherbyana), which grows to 10 feet.

Introduced Species in the Galapagos Islands

The Galapagos Islands have 240 species of plants which were brought here by humans. Settlers, especially farmers, introduced flora to these islands which have in some cases overtaken the native species. There are no islands in the Galapagos where this is more true than San cristobal, Floreana, and Santa Cruz. The Galapagos National Park Service has made introduced species a major point of concern and is working to reverse the damages caused by dominant introduced vegetation. These dominant aggressive species brought here by settlers are very efficient at dispersing their seeds and destroying their competitors. One of the worst of introduces Galapagos Islands plants is guayaba. Others include:

• Cabuya Cactus, or Furcraea cubensis
• Pinnata, or Kalanchoe
• Lantana, or Lantana camara
• Aguacate avocado, or Persa americana
• Elephant Grass
• Pomarosa fruit, or Eujenia jambos
• Toronja Limon fruit, or Citrus
• Pangola, or Digitaria decumbens

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