The head of H. arborea is rounded, the lip drops strongly, the pupil has the shape of a horizontal ellipse, and the tympanum is clearly recognizable.

[5] Members of the H. arborea species complex are the only representatives of the widespread tree frog family (Hylidae) indigenous to mainland Europe.

[7] This species complex is native to these countries: Albania; Armenia; Austria; Azerbaijan; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Cyprus; the Czech Republic; Denmark; France; Georgia; Germany; Greece; Hungary; Israel (found in the Ayalon Valley); Italy; Latvia; Liechtenstein; Lithuania; Luxembourg; Macedonia, the Republic of; Moldova; Montenegro; the Netherlands; Poland; Portugal; Romania; the Russian Federation; Serbia; Slovakia; Slovenia; Sweden; Switzerland; Turkey; Ukraine.

[1] European tree frogs can be found in marshlands, damp meadows, reed beds, parks, gardens,[7] vineyards, orchards, stream banks, lake shores,[10] or humid or dry forests.

[4] They tend to avoid dark or thick forests,[10] and they are able to tolerate some periods of dryness; therefore, sometimes they are found in dry habitats.

[4] European tree frogs reproduce in stagnant bodies of water, such as lakes, ponds, swamps, reservoirs, and sometimes puddles,[1] from late March to June.

[1] Some of the main threats to European tree frogs include habitat fragmentation and destruction, pollution of wetlands, predation from fish, capture for the pet trade,[10][1] and climate change.

[citation needed] Besides these main threats, other possible reasons for the decline in their populations include increased UVB radiation and local and far-ranging pesticides, fertilizers, and pollutants.