The genus Riccia comprises small, thalloid liverworts commonly found in moist or periodically wet habitats, such as muddy fields, riverbanks, and disturbed soils. Unlike many other liverworts, Riccia species are often adapted to temporary habitats and can rapidly colonize open ground. Their flat, rosette-forming thalli lack a distinct midrib and often exhibit a purplish underside due to anthocyanin pigments. Some species are considered pioneer organisms, playing a role in early succession and soil stabilization (Schuster, 1992).
Riccia species typical of ponds, ditches, creeks, lakes, siltation zones:
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| Riccia fluitans in its terrestrial form, a typical Riccia growing on mud in a pond |
Some Riccia species occur in both terrestrial and aquatic environments. Terrestrial forms are typically found in damp soil, often in disturbed areas like agricultural fields or muddy paths, where they form compact, rosette-shaped thalli that lie flat against the substrate. In contrast, aquatic forms such as
Riccia fluitans are free-floating, with delicate, branching thalli and can form dense mats at the water surface. These aquatic forms lack the structural adaptations for anchoring to soil and rely on water for both support and nutrient absorption (Jung, Kim, & Yoon, 2009).
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| typical habitat of Riccia fluitans, here in its aquatic version |
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| Aquatic form of R. fluitans growing on ice of a frozen lake |
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| Ricciocarpons natans in its aquatic form, swimming on the water, the terrestrial form can be similar to R. fluitans |
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| Riccia huebeneriana, a small Riccia also growing on mud in ponds |
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| Habitat of R. huebeneriana |
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| R. huebeneriana |
Typical Riccia species of damp soil, agricultural fields etc:
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| Riccia sorocarpa, a typical riccia on agricultural fields |
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| R. sorocarpa |
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| R. glauca, growing anywhere on damp mud or soil |
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| Habitat of R. glauca |
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| Sporophytes of R. glauca shining through the thallus cells |
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| R. glauca, note the bright green color, in comparison to the bluish green of R. sorocarpa |
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| R. carvenosa, characteristical grooves in the thalli |
Reference
Schuster, R. M. (1992). The Hepaticae and Anthocerotae of North America (Vol. 5). Columbia University Press.
