Taphrina nana Johanson, 1886
clear witches’ brooms, with upwards directed branches; yellowing of the leaf, not accompanied by any swelling of the leaf or the shoot. On the leaf (initially only hypophyllous) a layer of erect, cylindrical asci, 10-30 µm high, each on a low base cell, containing 8 spores that often already have started to divide. Arctic-alpine species
Betula nana, pendula, pubescens.
Taphrina alpina Johanson, 1886; Exoascus nanus (Johanson) Sadebeck, 1893; E. alpinus (Johanson) Sadebeck, 1893.
Bataille (1936a), Brandenburger (1985a: 52), Buhr (1964b), Klenke & Scholler (2015a), Mix (1949a), Tomasi (2014a).