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| Riccia | |
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| Riccia huebeneriana | |
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| Genus: | Riccia L., 1753
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Riccia is a genus of liverworts in the order Marchantiales. The genus consists of more than 150 species, of which the majority occurs in regions with a mediterranean climate.
Description
editThe genus consists of little liverworts, living on the soil or in water, which can be annual or perennial. The thallus is dichotomously branched to form a rosette. Cilia and Papillae are sometimes present near the thallus margin. The parenchyme either consists of loosely organized chlorenchyme or of compact cell rows without any organisation. In all species of this genus oil bodies are absent. The sporophytes are immersed and the spores are released after decay of the thallus. Each capsule contains 32-1350 spores with a diameter of 40-200 µm. The presence, number and size of alveolae on the surface of the spores can be an important characteristic of determination.
Distribution and habitat
editThe genus has a cosmopolitan distribution, whereas the majority of species occurs in regions with a mediterranean climate. Essential for the occurrence of Riccia is a periodical change of drought and moisture. Therefore the genus lacks in tropical regions without a dry season. Most Riccia species grow on disturbed clayey or loamy soil or floating in water. Most of the species are
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