Polycoma Pasilot de Bauvois, 1808 unaccepted Thorella B. Gaillon, 1883 unaccepted Thorea is a genus of fresh water algae in the division Rhodophyta (red algae).

[1] Thorea is a small alga with filaments up to 200 cm long, dark green in colour and not red as are marine Rhodophyta.

[2] The genus was circumscribed by Jean Baptiste Bory de Saint-Vincent in Ann.

[3] The genus name of Thorea is in honour of Jean Thore (1762–1823), who was a French botanist and physician who practiced medicine in the town of Dax.

[1] The first record of Thorea ramosissima in the British Isles is in Harvey's Manual (1841):[5] Found in a pool in a bog in the County Donegal Mountains, going from Letterkenny to Dunfanaghy; July.