Alnus cordata (Italian Alder)


Michael's Opinion

A handsome and fast growing specimen tree that can also be used in windbreaks, parks and gardens. It has very interesting male and female flowers and quite prominent cones.

Botanical Information

FamilyBetulaceae
GenusAlnus
Speciescordata
CategoryWoody
TypeTree (deciduous)
OriginSouthern Italy, France and Albania.
Pronunciation

Details

USDA Hardiness Zone6a - 9b
USDA Hardiness Ref.
Canadian Hardiness Zone5a - 8b
Canada Hardiness Ref.
RHS Hardiness ZoneH7
RHS Hardiness Ref.
Temperature (°C)-23 - (-1)
Temperature (°F)-10 - 30
Height25 m
Spread6 m
GrowthFast
Flowering PeriodApril

Description and Growing Information

General DescriptionA handsome, large, and fast growing tree usually found in gardens or in parks. Provides excellent screening or windbreaks and winter interest. It is tolerant of a wide variety of soils and growing situations including pollution. This species has been placed on the IUCN Red List as least concern.
ID CharacteristicEasily identified by the pronounced male catkins in early spring and the female flowers that produces small upright cones. The glossy green oval -round shaped leaves are typical of most Alder species.
ShapeUpright and narrow crown.
LandscapeWorks well in a large garden or as a street tree, as a specimen tree in a park, but are most desirable for windbreaks and screening. Provides shelter because of its fast growing nature.
PropagationSeed and hardwood cuttings. Seeds should be planted when ripe and will germinate in spring when the weather warms. When seedlings are large enough transplant into individual pots. Cuttings from taken from hardwood in autumn when the leaves fall and rooted in sandy soil will also work well.
CultivationFull-partial sun, it can tolerate acidic, neutral, and alkaline soils. Tolerates dry, loamy, and clay soils but is very tolerant and thrives even in wet and poor soil conditions. Very pollution tolerant and resistant to wind.
PestsIn alkaline soils it can become susceptible to chlorosis. Identifiable by abnormally small leaves that have turned a yellowish- brown colour.
Notable SpecimensThe Niagara Parks Botanical Gardens, Niagara Falls, Ontario, Canada. Westonbirt, The National Arboretum, Tetbury, Gloucestershire, England.
Bark/Stem DescriptionWhen the bark is young it is a greenish-gray colour and has a large number of visible lenticels. When the bark matures it becomes a grayish-brown colour and has flat ridges.
Leaf DescriptionA glossy green leaf with a tint of orange at the start of a new season. The leaf is simple, alternate, and rounded to somewhat oval in shape. Leaves are broad, 6 cm in width and 5-10 cm in length.
Flower DescriptionThe male flowers produce catkins that are 5-8 cm in length. They are a yellow- green colour and hang in clusters. The catkins are borne in early spring before the leaves appear. The female flowers are small, about 6 mm in length. They are a reddish- green colour that will eventually develop into a small cone. The cones appear in early spring and are persistent into the winter.
Fruit DescriptionRipens in early spring and continues through winter. A cone like fruit 20- 25 mm in length. Originally green in colour, when ripe it turns a reddish-brown: contains a large amount of winged seeds.
Colour DescriptionLeaves are a glossy green with a hint of orange at the start of a new season. The catkins are a greenish- yellow and the cones are a reddish- green.

Photographs