It is a ritual steeped in pagan mystery, updated for the coronavirus age.
Sick people in northern France occasionally leave garments in healing trees or "arbres à loques" in the hope of a cure, following a tradition that persists since pre-Roman times.
But locals who pay attention have noticed a recent change.
"The new development in 2020 is COVID masks," said Bertrand Bosio, who runs Nord Fantastique, a Facebook page devoted to the region's ancient sites and lore.
Tied to the branches of the healing tree in Hasnon, southeast of Lille, surgical masks can be clearly seen among items of clothing that range from socks to underwear - often left, Bosio said, by people suffering from fertility problems.
In another departure from ritual, the votive masks are hung "preventatively", Bosio believes - or perhaps hopes - rather than by COVID-19 sufferers who ought to be self-isolating.
Known as rag trees in Ireland, one of several other countries where the practice survives, the arbres à loques show pagan and Christian influences. Despite appearances, which can be disconcerting, they still bring people hope, he said.
"What's interesting about this place is that the ritual is still very much alive in our times," Bosio added.
"People turn to the healing tree when medicine has reached its limits, and when science has let them down."
(This story corrects location of Hasnon to southeast of Lille, not southwest)
(Writing by Laurence Frost. Editing by Jane Merriman)
