The Flora of the Galapagos: The Humid Zone

The varied flora of the Galapagos Islands survives in markedly different vegetation zones, which are spread across the archipelago. The regions commonly known as the "humid zones" are found only in the higher elevations of the largest islands and comprise three separate types of vegetation: Pampa (and ferns and sedges), Miconia and Scalezia.

The Humid Zone Flora of the Galapagos

The different habitat zones of the archipelago are created by their vastly differing environmental factors, including the amount of precipitation, temperatures, winds and, primarily, their elevation. The lush, moist habitat of the high altitudes supports a wide range of flora and fauna.

Scalezia

The Scalezia trees are part of the aster family and grow in the lower reaches of the humid zone. There are at least 20 species, some of which can reach up to 60 feet. Their trunks are usually covered with mosses, orchids and other epiphytes, which are encouraged by the damp, thick fog that often shrouds these elevated areas. Unfortunately, the native Scalezias are under threat from the introduced guava, which grows in abundance, quickly depleting the amounts of available nutrients in the surrounding soils. Other species found here include the Galapagos Cafetillo and Passion Flowers.

Zanthoxylum

The next level of elevation primarily supports the Zanthoxylum fagara, known colloquially as the Cat's Claw, along with a host of bracken ferns, liverworts and a carpet of lichens and mosses. It is the presence and appearance of these last two that also earns the region its other common name: the Brown Zone.

Miconia

There are only two islands where the endangered Miconia shrub still survives on the next level of elevation (around 3,200ft) – Santa Cruz and San Cristobal. While at one time this shrub grew in abundance, its numbers have been drastically reduced due to the presence of agriculture and invasive introduced plant species, such as the quinine tree. The striking Miconia robinsoniana grows to some 16 feet and produces beautiful pink and purple blooms. The endemic cotton plant of the archipelago is also found in this region.

Ferns, Pampas and Sedges

The most extreme elevations of the largest islands are home to the ferns, sedges, orchids, liverworts, lichens and grasses that are able to retain moisture and survive the buffeting winds. The survival of the plant species in these areas depends entirely on the amount of rainfall they receive, and they can vary in appearance. The only tree that survives up here is the endemic tree fern, Cyathea weatherbyana, which can grow to an impressive height (up to 10 feet). It is able to sustain periods of dry weather, preferring to grow around small potholes or craters of water secreted in ravines or gullies.

Threats to the Endemic Flora of the Galapagos

The major threats to the survival of the flora of the Galapagos are agriculture (through farming and cattle grazing) and invasive species taking over the habitat. The vast majority of invasive species were introduced by humans and, thankfully, are mainly found on the inhabited islands. Guava and quinine, however, which are two of the most prevalent and problematic species in terms of threats to native vegetation, are found on several of the islands in damaging proportions.

The good news, though, is that scientists have determined that around 95% of the flora of the Galapagos Islands remains untouched. Numerous conservation projects are in place to ensure that this status quo endures and, while continued efforts are required, the archipelago looks set to remain one of the most botanically diverse places on the planet.

Author Plate

Marissa Ellis-Snow is a freelance nature writer with a special interest in the unique flora of the Galapagos Islands. Marissa chooses the expert-led itineraries organised by Naturetrek, which have brought her unforgettable sightings of a wide range of flora and fauna in one of the most spectacular regions on Earth.