Alnus glutinosa - Alder
Alders are a very familiar sight along riverbanks. They thrive on
waterlogged soil and their roots help to limit erosion during heavy spates
(high, fast flowing water). For many decades alders were coppiced and the
wood used to make charcoal.
In the 1990s, a disease (a fungus of the Phytophthora
genus, some species of which attack potato crops) destroyed many of the
alders beside rivers. The River Towy is badly affected in its middle
reaches, for example; the diseased trees pictured above were photographed
near Llandeilo.
The alder catkins shown above are male (on the left) and female (on the
right); they form in the autumn (which is when this picture was taken) and
pollination occurs in the following spring.
The leaves are initially sticky with hair on the underside (unlike
hazel, which has hairs on both sides of its leaves). Alder leaves are
generally smaller and darker than those of hazel, with which it is
sometimes confused.
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