(pl. propagules)
Terms discussed: isidium (pl. isidia), soralium (pl. soralia), soredium (pl. soredia)
Topics:
propagule
isidium
soredium
See Also:
Lichen
propagule
A propagule is any part of an organism that can be detached from the organism and disseminated in hopes of it growing into a new biont in a new environment. Sexual spores (ascospores and basidiospores) and the various kinds of conidia are the two most common and well-known types of propagule used by fungi. Except for propagation by dispersal of small, randomly detached mycelial fragments (the only method left to non-yeast fungi that do not produce spores), the methods specific enough to have a name but unusual enough not to get their own entry all belong to lichens.
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isidium
An isidium is a coral-like, branching structure that breaks off from the main lichen thallus and can grow into a new lichen. It contains cells from both the mycobiont and the photobiont. Because of its relatively large size and weight, an isidium is usually only dispersed a short distance from its parent lichen.
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soredium
Soredia are tiny balls of one or a few photobiont cells surrounded by fungal tissue. They are usually produced in a powdery mass in a specialized portion of the lichen thalus called a soralium. Because of their relatively small size and weight, soredia are easily dispersed great distances from the parent lichen.
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Lichens also propagate themselves by bits of the thallus that just break off and hopefully start another lichen somewhere else. I don't think that there's any particular name for this sort of propagule.
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