The genus Trentepohlia would not, at first glance, be taken as a green alga. Free-living species are mostly yellow to bright orange or red-brown in colour, due to the orange pigment, haematochrome (β-carotene), which usually hides the green of the chlorophyll. The genus is terrestrial and is often found in Europe on rocks, walls and tree bark. Where they are found on buildings, they can cause severe mechanical degradation and deterioration.
Fabio Rindi and Michael D. Guiry (2002) have identified five species of the genera Trentepohlia and Printzina in urban habitats in Western Ireland: Trentepohlia abietina (Flotow) Hansgirg, T.aurea (Linnaeus) Martius, T. iolithus (Linnaeus) Wallroth, T.cf.umbrina (Kützing) Bornet, and Printzina lagenifera (Hildebrandt) Thompson et Wujek. These species formed perennial populations on a variety of substrata. Of the species identified, T.aurea and T.iolithus were found on old concrete and cement walls; in particular, the latter species formed characteristic, extensive, deep-red patches on many buildings.
Western Ireland is a cold temperate area with high levels of rainfall and humidity. This area therefore supports a high level of rich and diversified algal flora. Trentepholia have been identified as one of the most common species to be isolated from walls and buildings in this region (Rindi, Guiry 2002).