Taphrina bacteriosperma Johanson, 1887
the leaves are discoloured and abnormally enlarged; no formation of a definite witches’ broom. Generally all leaves of a shoot are affected. On the leaf (mostly only the upper side) a layer of erect, cylindrical asci, 30-80 µm high, not on a basel cell, of which the original eight spores have been transformed into a mass of bacterium-sized cells. Arctic species.
Betula nana, nana x pubescens, pendula, pubescens.
Bataille (1936a), Buhr (1964b), Klenke & Scholler (2015a), Mix (1949a, 1935a).