Italian Alders are the last Alders to shed their leaves and may still be in leaf in December. All images and text are taken from the book Field Guide to the Trees of Britain and Europe published by Reed New Holland in 2017, author Alan Birkett and ISBN 9781921517839.

Italian Alder
Italian Alder leaf

The Italian Alder, native to Italy and Corsica, was introduced in 1820 and is now common in parks, gardens and urban areas. It grows rapidly and is highly tolerant of urban pollution. It has catkins like the other Alders but the female cone-like catkins are bigger than those on the Common and Grey Alder. It has glossy heart-shaped leaves that stay on the tree until November or December. The first photo shows a tree in August, the second shows the glossy leaf. 

Alders have male and female flowers on the same tree. The flowers have no petals – they take the form of catkins. Male catkins are formed in spring, grow upright through the summer and then hang down through the winter until they shed pollen in February/March. Female flowers are pollinated in February/March, grow into round green cone-like catkins in the summer and turn brown and shed seeds in autumn and winter. Female catkins stay on the tree through the winter and the following summer.

Italain Alder male catkin
Italian Alder female catkin
The first photo is a close-up of male catkins in March before shedding pollen. The red anthers are not yet open to release pollen. The second photo shows a woody, cone-like, female catkin, which on the Italian Alder are bigger than on any other Alder. This is a female catkin that has released its seeds in autumn, photographed in the following July.