Scientific Name– Alnus cordata Loisel.

Synonim– Alnus cordifolia

Common name(s)– alder of Corsica, Hartbladige Els, Italian alder, Ontano napoletano, Herzblattrige Erle.

Distribution and Habitat– native to Corsica and South Italy; occurs naturally on damp soils, in poorly drained areas and depressed sites.

Description– deciduuous tree, 10-15 (30) m tall; crown ovoid-conic. Bark greenish grey with numerous lenticels when young, later becoming a light grey-brown with small fissures. Twig slender, olive green, lenticels. Buds are stalked, green turning red an 0.6 cm long.

Leaves alternate, simple, broadly oval to rounded, 5-10 cm long, base cordate, margin unevenly toothed, glossy green above, paler with a few scattered brown hairs below in vein axils and along midrib, petioles 2-3 cm long. Flowers monoecious, males flowers yellow-green, in aments elongated, 5-13 cm long, in clusters 3-5 (2); females flowers 6 mm, reddish green turning into a small cone, strobil 2.5-3 cm long, persistent in winter. Flowering in February-March. Fruit woody, 2 - 2.5 cm long, green turning reddish brown when ripe. Winged seeds.

Growth rate– fast growth.

Tolerances– it tolerates wet soil, but needs ample water.

Requirements– does well in dry, acid, neutral and alkaline soil.

Management–

Propagation– seeds are best sown in a cold frame as soon as it is ripe and only just covered. When large enough to handle, seedlings should be pricked  out into individual pots. Plant them out into their permanent positions in the summer.

Alnus cordata can also undergo stratification for 90 days at 1-2°C.

Cuttings of mature wood, should be taken as soon as the leaves fall in autumn, and be planted outdoors in sandy soil.

Pest and Diseases– is susceptible to chlorosis in very alkaline soils.
Garden Partners–

Cultivars– 'Sipkes' 20 m tall, dark and glossy green leaves, recommended habit for a street tree.

Properties and Uses– the tree is grown as an ornamental in gardens and parks and as a road-side. Is a windbreak or hedge for maritime areas.

Alder trees has a symbiotic relationship and fix atmospheric nitrogen, utilized by the growing plants and enables it to grow well in quite poor soils.

Curiosity–

Bibliography

Andreas Roloff, Andreas Bartels - Flora der Geholze - Ulmer, 2008

Cecil C. Konijnendijk, kjell Nilsson, Thomas B. Randrup, Jasper Schipperijn -  Urban Forest and Trees - Springer, 2005

Katharina Pawlowski, William E. Newton - Nitrogen-fixing Actinorhizal Symbioses - Springer, 1ed, 2007

Michael A. Dirr - Dirr's Hardy Trees and Shrubs - Timber Press, 2ed, 1997