Solanum cheesmaniae is one of two wild tomato species endemic to the Galapagos archipelago (2). Having evolved in isolation from mainland tomato species, it exhibits a range of unusual characteristics, such as bright orange-yellow fruit, yellow-green foliage and minute seeds (3). Although it initially grows upwards, mature plants often spread along the ground, with the hairy stems branching profusely (4) (5). The spear-shaped leaves are relatively small, fleshy and sticky, while the yellow flowers are covered in hairs like the rest of the plant (6) (7). It is morphologically quite variable across the archipelago, but owing to a strong dependence on self-pollination, individuals within each population are strikingly uniform in appearance (6). Until relatively recently, the only other endemic wild tomato species, S. galapagense, was considered a subspecies of S. cheesmaniae, but is now treated as a separate species (2) (4).
- Lycopersicon cheesmaniae.
- Height: up to 2 metres (2)
Galápagos tomato biology
S. cheesmaniae flowers and fruits throughout the year, but exhibits a flowering peak at the beginning of the Austral winter, between April and June (4). Although the flowers are structured in a way that favours self-pollination, some cross-pollination is thought to be likely, with the native Galápagos bee (Xylocopa darwinii) being a possibly pollinator (2) (3). Passage through the gut of a giant tortoise was originally thought to be a requisite for seed germination (6), but recent evidence suggests this may not be entirely true, particularly given that S. cheesmaniae occurs on islands that possibly never had a tortoise population (2).
Galápagos tomato range
Endemic to the Galapagos Islands where it occurs on several of the major islands and smaller islets (2).
Galápagos tomato habitat
Owing to high salt tolerance, S. cheesmaniae is able to thrive on coastal lava flows within close range of the sea, but also grows on slopes up to 1,300 metres above sea level (2) (3) (4).
Galápagos tomato status
This species has not yet been assessed by the IUCN (1).
Galápagos tomato threats
Human activity and introduced animals, such as feral donkeys and goats, threaten many S. cheesmaniae populations. In addition, introduced tomato species have the potential to genetically contaminate the endemic species through interbreeding (2) (3).
Galápagos tomato conservation
The endemic Galapagos tomatoes are considered to be of great value to the breeding of the cultivated tomato, and consequently of great conservation significance. It is currently thought that the best means of conserving the endemic species is to establish protected reserves that exclude introduced herbivores and are free from introduced plants (2) (3).
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For further information on the conservation of the endemic flora of the Galapagos see:
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- The transfer of pollen between flowers on different plants.
- A species or taxonomic group that is only found in one particular country or geographic area.
- An animal that in the act of visiting a plant’s flowers transfers 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.
- Transfer of pollen within the same individual plant- either within the same flower, or between different flowers.
- 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 (June, 2009)
Darwin, S.C., Knapp, S. and Peralta, I.E. (2003) Taxonomy of tomatoes in the Galápagos Islands: Native and introduced species of Solanum section Lycopersicon (Solanaceae). Systematics and Biodiversity, 12: 29 - 53.
Nuez, F., Provens, J. and Blanca, J.M. (2004) Relationships, origin, and diversity of Galapagos tomatoes: implications for the conservation of natural populations. American Journal of Botany, 91: 86 - 99.
Natural History Museum - Solanaceae Source (June, 2009)
Wiggins, I.L. and Porter, D.M. (1971) Flora of the Galapagos Islands. Stanford University Press, Stanford.
Jackson, M.H. (1993) Galapagos: a natural history. University of Calgary Press, Calgary.
Eu-Sol (June, 2009)