Ten Alnus species compared through exact Wikimedia Commons photographs of growth forms and foliage. An editorial selection, not a scientific ranking. Original video contributions: CC BY-SA 4.0. Individual photographs retain the licences and credits listed in attribution; public-domain and CC0 photographs remain so. Photograph credits: 1. File:Alnus glutinosa kz32.jpg; Krzysztof Ziarnek, Kenraiz; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Alnus_glutinosa_kz32.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 2. File:Alnus incana rugosa leaves.jpg; Quadell; CC BY-SA 3.0; http://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Alnus_incana_rugosa_leaves.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 3. File:Leaf 3262.jpg; Chris Light; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Leaf_3262.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 4. File:Alnus cordata.jpg; Franz Xaver; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Alnus_cordata.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 5. File:Alnus japonica2.jpg; KENPEI; CC BY-SA 3.0; http://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Alnus_japonica2.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 6. File:Alnus serrulata.jpg; Eric Hunt; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Alnus_serrulata.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 7. File:Alnus rhombifolia NPS.jpg; US NPS Santa Monica Mountains National Recreation Area [2]; Public domain; ; https://commons.wikimedia.org/wiki/File:Alnus_rhombifolia_NPS.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 8. File:Alnus acuminata 1.jpg; Frank R 1981; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Alnus_acuminata_1.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 9. File:Alnus orientalis kz4.jpg; Krzysztof Ziarnek, Kenraiz; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Alnus_orientalis_kz4.jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence. 10. File:Alnus nepalensis in Hackfalls Arboretum (2).jpg; Krzysztof Golik; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Alnus_nepalensis_in_Hackfalls_Arboretum_(2).jpg; Whole-image fit and scaling; title and caption bars added. Photograph licensed under the stated source licence.