Riccia glauca
Riccia glauca L.
Ricciaceae
Conservation status. Endangered [EN B2ab(iii)c(ii)].
Morphology and biology. Annual thalloid liverwort forming complete rosettes c. 15 mm diameter, green or bluish but pale when dry. Thallus 2–3 times dichotomously branched, 5–8 mm long and 1–3 mm wide, thick, with broad and shallow channel in the middle, well defined towards lobe tips. Ventral scales hyaline (transparent and colourless). Often forms sporophytes. The spores are dark brown, areolate (with small angular-shaped areas on surface). Does not form gemmae. Bisexual.
Habitats and populations. Plants grow on moist sandy soils in stubble fields, pond margins, paths, roadsides and banks in lax herb and shrub communities, and on exposed places in forest areas. Often could be found together with other Riccia species. A change in population density over the years is possible if there are no ecological conditions suitable for the species’ development. The species is characterized by limited dispersal potential and low growth rate.
Distribution in Bulgaria. Sofia Region (Sofia –Borisovata Gradina park and near Vladaiski quarries), Rhodopi Mts (Western – Batashko Blato mire), Tundzha Hilly Country (Sakar Mt.).
General distribution. Balkan Peninsula (Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Montenegro, Serbia) and most other parts of Europe, N Africa, Siberia, Far East, W and E Asia, China, New Zealand, NW Pacific, North America. Sub-Mediterranean species.
Threats. The habitat (exposed moist soils) is a vulnerable one. The localities of the species are found in built-up areas and in regions with intensive human activities. Other threats include agriculture activities, afforestation, infrastructure development (e.g. reservoir construction), and soil contamination. Under-grazing and plants community changes towards shrubs and trees cause loss of suitable microhabitats, such as exposed soils covered with lax herbaceous vegetation.
Conservation measures taken. Some localities are within sites of the European ecological network Natura 2000 in Bulgaria.
Conservation measures needed. Long-term studies and assessment of dynamics of populations development; elaboration of action plans.
References. Arnaudoff 1909; Stefanoff & Petrov 1962.
Author: Anna Ganeva
