A rock-dwelling species, Gloeoheppia turgida is a ‘squamulose’ lichen, meaning that the main body (thallus) is entirely covered in minute scales. The thallus is partially gelatinous (viscous, like jelly), often with large internal air spaces, and is generally dark brownish to yellowish-olive in colour, although it may rarely appear to have a white-grey powdery covering (2).
Lichens are a unique group of organisms that consist of two components, a fungus (called the ‘mycobiont’) and an alga or cyanobacterium (called the ‘photobiont’) that live in a close symbiotic relationship (6)(7)(8). The fungus produces the thallus (the main lichen body) which houses the alga or the cyanobacterium, providing protection and creating optimal conditions for the photobionts to photosynthesise. This process produces sugars and nutrients which can then be utilised by the fungus(8).
Like other lichens, Gloeoheppia turgida is poikilohydric, hence the lichen is able to desiccate (remove water) completely and suspend photosynthesis until more favourable conditions return. This remarkable ability has allowed lichens to colonise a wide range of habitats in which higher plants are unable to survive (3). In deserts, lichens with cyanobacterial components, like the lichen Gloeoheppia turgida, are important as they provide most of the fixed nitrogen to the ecosystem (6). Many lichens are known to be very sensitive to environmental pollution, and, consequently, are used as 'indicators' of the levels of pollution in an area (7).
A simple plant that lacks roots, stems and leaves but contains the green pigment chlorophyll. Most algae occur in marine and freshwater habitats.
A group of bacteria that contain the pigment chlorophyll and are able to photosynthesise. Once known as ‘blue-green algae’, cyanobacteria are thought to have been the first organisms to produce oxygen; fossil cyanobacteria have been found in 3000 million year old rocks. As they are responsible for the oxygen in the atmosphere they have played an essential role in influencing the course of evolution on this planet.
Fungi are one of the taxonomic kingdoms, separate from plants and animals. They obtain nutrients by absorbing organic compounds from the surrounding environment.
Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
Organisms unable to regulate their water content to any significant degree, and able survive for long periods of time in a virtually dry state, resuming normal metabolic functions when re-wetted.
Describes a relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).
Type of simple plant body that does not have stems, leaves and roots.
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