Another name for the plant is "hortensia" — and that's the name in French. Ce sont des hortensias. Hydrangeas are native to eastern Asia (many species) and North America (a few species).
Hortensia is not a botanical or scientific name for the plant. That name is hydrangea. Hortensia is a horticultural term that describes the hydrangea hybrids that we plant in our yards.
Above are some hortensias as depicted by the French réaliste/intimiste painter Henri Fantin-Latour (1836-1904).