Ciliate Crystalwort

Ciliate crystalwort (Riccia crozalsii) is a thalloid liverwort in the family Ricciaceae, classified as Vulnerable in Europe. It grows as a flat, strap-like or rosette-forming thallus, typically in damp, disturbed or ephemeral habitats such as the margins of seasonal pools, rutted tracks, and temporarily flooded ground with sparse vegetation cover. The species is characterized by thallus margins fringed with fine cilia-like teeth, which give it its common name. Riccia crozalsii is found in Mediterranean and Atlantic regions of Europe, with records from Spain, Portugal, France, Italy, and parts of the British Isles, though populations are generally sparse and localized. It tends to appear in winter and spring when suitable wet conditions prevail, and the thallus desiccates or disappears during dry summer months. The species is assessed as Vulnerable due to the loss and degradation of its specialized ephemeral wetland habitats, driven by drainage, agricultural intensification, and altered hydrological regimes across Europe. As with many liverworts dependent on wet, open habitats, Riccia crozalsii has experienced declines in regions where traditional low-intensity land management practices have been abandoned. Monitoring and protection of ephemeral pool and wetland margins are key conservation actions for this species.