Alnus alnobetula 2 between Lans en Vercors and Villard-de-Lans FR 150702 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 1 DBVs Garden, Visby, Gotland 110508 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 5 Kungsholmen, Karlskrona, Blekinge 190531 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 6 Kungsholmen, Karlskrona, Blekinge 190531 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 1 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 13 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 14 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 15 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 16 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 2 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 3 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 6 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 7 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 8 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 9 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 1 (cult) Höllviken Sk 130805 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 11 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 6 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus serrulata Storrs, Connecticut 900613 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus sinuata 1 Lund Bot Garden 130527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus sinuata 2 Lund Bot Garden 130527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus sinuata 3 Lund Bot Garden 130527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus subcordata 1 Bergianska 150527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus subcordata 2 Bergianska 150527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus subcordata 3 Bergianska 150527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus alnobetula 1 between Lans en Vercors and Villard-de-Lans FR 150702 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus alnobetula 3 between Villar d'Arène and Col du Lautaret FR 150707 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus alnobetula 4 between Villar d'Arène and Col du Lautaret FR 150707 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 2 DBVs Garden, Visby, Gotland 110508 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 3 DBVs Garden, Visby, Gotland 110508 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 4 DBVs Garden, Visby, Gotland 110508 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 7 Kungsholmen, Karlskrona, Blekinge 190531 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 8 Kungsholmen, Karlskrona, Blekinge 190531 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus cordata 9 Kungsholmen, Karlskrona, Blekinge 190531 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 10 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 11 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 12 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 12 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 17 Lund Sk 130919 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 4 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus glutinosa 5 Lund Sk 130401 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 10 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 2 (cult) Höllviken Sk 130805 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 3 Lund Sk 090329 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 4 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 5 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 7 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 8 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus incana 9 Höllviken Sk 130331 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus sinuata 4 Lund Bot Garden 130527 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus sinuata 5 Bergianska 050513 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Alnus viridis Bergianska 050513 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).