Italian Alder

Italian Alder (Alnus cordata) is an alder native to southern Italy (including Sardinia) and Corsica.

It is a medium-sized tree growing to 17–25 m tall (exceptionally to 28 m), with a trunk up to 70–100 cm diameter. The leaves are deciduous but with a very long season in leaf, from April to December in the Northern Hemisphere; they are alternate, cordate (heart-shaped), rich glossy green, 5–12 cm long, with a finely serrated margin.

The slender cylindrical male catkins are pendulous, yellowish in colour and 5–10 cm long; pollination is in early spring, before the leaves emerge. The female catkins are ovoid, when mature in autumn 2–3 cm long and 1.5–2 cm broad, dark green to brown in colour, hard, woody, and superficially similar to some conifer cones. The small winged seeds disperse through the winter, leaving the old woody, blackish 'cones' on the tree for up to a year after.

Like other alders, it is able to fix nitrogen from the air. It thrives on much drier soils than most other alders, and grows rapidly even under very unfavourable circumstances, which renders it extremely valuable for landscape planting on difficult sites such as mining spoil heaps and heavily compacted urban sites.