Galapagean Littoral Zone
Ranging from lava boulders to sandy beaches, this zone is colonized by salt tolerant species such as Avicennia germinans, Batis maritima, Conocarpus erectus, Cryptocarpus pyriformis, Heliotropium curassavicum, Ipomoea pes-caprae, Laguncularia racemosa, Rhizophora mangle, Scaevola plumieri, Sporobolus virginicus and Trianthema portulacastrum. The endemics included Cyperus anderssonii (Cyperaceae), Exedecunus miersii Galapagos shore petunia (Solanaceae), Lithophila radicata (Amaranthaceae), Lycium minimum Galapagos lycium (Solanaceae), Nolana galapagensis Galapagos clubleaf (Nolanaceae), Polygala sancti-georgii var. sancti-georgii (Polygalaceae), Sesuvium edmonstonei Galapagos carpetweed (Aizoaceae) and Tiquilia darwinii (Boraginaceae). A rare and possibly extinct endemic recorded here is Philoxerus rigidus (Amaranthaceae), which has not been seen since 1906.
Galapagean Arid Zone
Dry for most of the year, this zone provides habitat for a range of xerophytic species capable of tolerating very dry conditions, with many of the leaf bearing species are deciduous. However, the most conspicuous plants are cacti (Cactaceae) such as the endemic Jasminocereus thouarsii and Opuntia echios, while one of the more conspicuous trees is Bursera graveolens (incense tree) whose grayish bark often gives this zone a ghostly appearance. Less conspicuous trees include the Erythrina velutina and the endemic Croton scouleri Galapagos croton (Euphorbiaceae). Shrubs, often spiny, are also common making certain areas almost impenetrable. Among several common species are the endemic Cordia revoluta (Boraginaceae), Gossypium darwinii Darwin’s cotton (Malvaceae), Lantana peduncularis Galapagos lantana (Verbenaceae), Scutia spicata var. pauciflora (Rhamnaceae), Scalesia affinis and Tournefortia pubescens (Boraginaceae). Herbaceous members of this zone include the endemic Aristida subspicata Galapagos three-awn grass (Poaceae) and Sarcostemma angustissimum Galapagos sarcostemma (Asclepiadaceae).
Galapagean Transition Zone
In the transition between the Arid and Scalesia zones, both deciduous and evergreen trees occur including Cordia lutea and endemics such as Pisonia floribunda Galapagos pisonia (Nyctaginaceae) and Psidium galapageium Galapagos guava (Myrtaceae). The Zone also has well developed shrub and herb layers providing habitat for endemics such as the perennial vine Cardiospermum galapageium Galapagos heartseed (Sapindaceae), two Tournefortia shrubs, T. pubescens and T. rufo-sericea (Boraginaceae), Plantago galapagensis (Plantaginaceae) and the endemic fern Polypodium tridens (Polypodiaceae).
Galapagean Scalesia Zone
This zone is characterized by members of the endemic genus Scalesia (Asteraceae), but depending on the island, this may be either Scalesia pedunculata (tree scalesia) or Scalesia microcephala (small-headed scalesia), together with various other endemic trees. Shrubs are well represented with endemics such as Darwiniothamnus lancifolius lance-leafed Darwin’s shrub and D. tenuifolius thin-leafed Darwin’s shrub (Asteraceae) and Psychotria rufipes white wild coffee (Rubiaceae) likely to be seen. A much more rare species is Pleuropetalum darwinii Galapagos pleuropetalum (Amaranthaceae). In the cool season these forests are shrouded in mist providing sufficient moisture for many epiphytes including endemics such as Epidendron spicatum (Orchidaceae), Passiflora colinvauxii (Passifloraceae), Peperomia galapogensis Galapagos peperonia (Piperaceae) and Phoradendron henslowii Galapagos mistletoe (Viscaceae). Among the many herbs is the endemic Justicia galapagana Galapagos justicia (Aizoaceae), while on marshy ground near ponds the endemic marsh plant Hydrocotyle galapagensis (Apiaceae) may be encountered. Finally this zone supports a rich fern flora with endemics such as Asplenium formosum var. carolinum (Aspleniaceae), Ctenitis pleiosoros (Aspidiaceae), Polypodium insularum (Polypodiaceae) and Thelypteris tetragona subsp. aberrans (Thelypteridaceae).
Galapagean Zanthoxylum Zone
This zone is dominated by Zanthoxylum fagara, but it is sometimes known as the ‘brown zone’ because of the many epiphytic lichens that turn brown during the cool season. However, much has been lost through human interference. The only endemics likely to be encountered are Tournefortia pubescens (Boraginaceae) and the clubmoss Lycopodium setaceum subsp. galapogense (Lycopodiaceae).
Galapagean Miconia Zone
This zone consists almost entirely of the endemic shrub Miconia robinsoniana Galapagos miconia (Melastomataceae). The only other shrub likely to be encountered is the endemic Psychotria rufipes (Rubiaceae). Endemics among the herbaceous flowering plants include Galium galapagoense (Rubiaceae) and Jaegeria gracilis Galapagos jaegeria (Asteraceae). Interspersed among the shrubs are various ferns including Pteridium aquilinum bracken and the endemic tree fern Cyathea weatherbyana Galapagos tree fern (Cyatheaceae).
Galapagean Fern-Sedge (Pampa) Zone
The main plant groups found here are clubmosses, ferns, grasses and sedges, and although trees are absent, the endemic Cyathea weatherbyana Galapagos tree fern (Cyatheaceae) can reach heights of 3 m. Other ferns include the endemic Ctenitis pleiosoros (Aspidiaceae) while the characteristic clubmoss is Lycopodium cernuum. Among the grass species is the endemic Paspalum galapageium var. galapageium (Poaceae), while the sedges include the endemic Cyperus grandifolius (Cyperaceae). Other endemic flowering plants that may be encountered include Pernettya howellii (Ericaceae), Pilea baurii (Urticaceae), Polygonum galapagense (Polygonaceae) and Verbena sedula var. sedula (Verbenaceae).
Further information required.
References
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