In this study, we observed the germination behaviour of airborne conidia from powdery mildews that settle on thalloid surfaces. We inoculated thalli (flat, sheet-like leaf tissues) and gemmae (small, flat, sheet-like leaf tissues that propagate asexually via bud-like structures) of the common liverwort (Marchantia polymorpha) with conidia from tomato powdery mildew (Oidium neolycopersici; KTP-02) and red clover powdery mildew (Erysiphe trifoliorum; KRCP-4N) and examined their germination and subsequent appressorium formation under a high-fidelity digital microscope. Conidial bodies and germ tubes of the inoculated KRCP-4N conidia were destroyed on both the thalli and gemmae. The destruction of these fungal structures was observed only for KRCP-4N conidia inoculated onto M. polymorpha on both leaf surfaces. No differences in destruction of the KRCP-4N fungal structures between thalli and gemmae were observed. At 4 h post-inoculation, destruction of the germ tube tip was observed when it reached the gemmae leaf surface. At 6 h post-inoculation, the conidial bodies and germ tubes were destroyed. In contrast, KTP-02 conidia were not destroyed and formed normal, well-lobed appressoria on the surface of M. polymorpha gemmae.