When you arrive in the Galapagos you'd think that the islands were quite inhospitable to trees. For the most
part, you'd be right. The arid lowlands receive too little rain to sustain expansive forests we might expect
in the tropics. A few species are adapted to survive, but mostly only a few species of cacti and specialist
plants do well.
Trees find a more welcoming environment higher up as temperatures cool slightly but,
more importantly, rainfall is higher. Vegetation in the Galapagos is strongly stratified according to the
availability of moisture and trees obey the dictates of the climate. (For more information see vegetation zones.) Coastal trees are predominantly mangroves; no others can
survive tides or the salt laden winds. In the dry zone common trees include palo verde (Parkinsonia
aculeata), poison apple (Hippomane mancinella), muyoyo (Cordia lutea) and four species of
acacia (Acacia spp.). Transition zone trees are primarily Galapagos guava (Psidium galapageium) and
two species of palo santo (Bursera spp.) while introduced bamboo (Bambusa gradua) is spreading into
native forests. The scalesia zone is dominated by daisy tree (Scalesia spp.) of which about 14 species are
known. Tree fern (Cythea weatherbyana) and cat's claw (Zanthoxylum fagara) are also present on
These and other native vegetation are threatened by cattle grazing and invasive
introduced species such as guava (Psidium sp.) and quinine (Cinchona succiruba)a problem that
is proving increasingly difficult to overcome.