Cactus (Jasminocereus thouarsii)
|Size||Height: up to 7 metres (2)|
Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3). Subspecies: Jasminocereus thouarsii var. delicatus, Jasminocereus thouarsii var. sclerocarpus and Jasminocereus thouarsii var. thouarsii are listed as Vulnerable (VU) on the IUCN Red List (1).
One of only two cactus genera native to the Galapagos, the scientific name of this species, is a reference to its attractive jasmine-like flowers (4). Jasminocereus thouarsii has a tree-like form, with a thick, columnar stem that usually separates into several branches. The stem is deeply ridged and bears clusters of long spines, with as many as 35 spines per cluster, which may be coloured white, yellow, reddish-brown or black (2). The flowers are striking, and comprise a long tube, ending in a whorl of white to olive-green petals. After pollination, the flowers die off, and are replaced by large, round or ovoid, fleshy fruits, which contain numerous black seeds (2) (4).
There are three varieties of Jasminocereus thouarsii, which may be distinguished by location, as well as by features such as fruit colour and flower size and texture. Jasminocereus thouarsii sclerocarpus has waxy textured flowers and greenish-red fruits; Jasminocereus thouarsii delicates has reddish-purple fruits and flowers that lack a waxy texture; and Jasminocereus thouarsii thouarsii has greenish fruits and also lacks waxy-textured flowers (2).
Endemic to the Galapagos Archipelago, Jasminocereus thouarsii sclerocarpus, is found on Fernandina and Isabela; Jasminocereus thouarsii delicates, occupies Bartolomé, Santa Cruz, Santiago and smaller islets; and Jasminocereus thouarsii thouarsii inhabits Floreana, San Cristóbal and the islet of Corona del Diablo (2) (4).
Jasminocereus thouarsii is found in the dry, lowland zone of the Galapagos islands between sea level and elevations up to 300 metres (2) (5).
The large, attractive flowers of Jasminocereus thouarsii open only at night, and are probably pollinated by nocturnal, flying insects such as moths (6). The fruits of this species are edible, and can be used to make a refreshing juice (2).
Like many plants on the Galapagos, Jasminocereus thouarsii has been negatively affected by human disturbance, particularly through the introduction of exotic plants and animals (7) (8). Feral goats have proven particularly problematic, consuming large quantities of endemic cactus species (8), and today all varieties of Jasminocereus thouarsii are considered rare (2).
In an effort mitigate the decline of Jasminocereus thouarsii, the Ecuadorian government strictly controls its collection and disturbance (4). In addition, the Galapagos conservation organisation, the Charles Darwin Foundation, is working to eradicate non-native species, thereby helping to preserve the Galapagos’ threatened, native wildlife (7).
To learn more about conservation in the Galapagos, visit:
- Charles Darwin Foundation:
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- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Genera: the plural form of genus, a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Nocturnal: active at night.
- Perennial: a plant that normally lives for more than two seasons. After an initial period, the plant produces flowers once a year.
- Pollinated: to transfer pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
- Pollination: the transfer of pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
IUCN Red List (May, 2009)
- McMullen, C.K. and Prance, G. (1999) Flowering Plants of the Galápagos. Cornell University Press, New York.
CITES (May, 2009)
- Anderson, E.F., Barthlott, W. and Brown, R. (2001) The Cactus Family. Timber Press, Portland, Oregon.
Charles Darwin Foundation (May, 2009)
- Jackson, M.H. (2001) Galapagos: A Natural History. University of Calgary Press, Calgary.
Charles Darwin Foundation (May, 2009)
- Schofield, E.K. (1989) Effects of introduced plants and animals on island vegetation: Examples from the Galapagos Archipelago. Conservation Biology, 3: 227 - 238.