Practical
Plants

Alnus cordata

Italian Alder

a deciduous tree of the Alnus genus in the family Betulaceae. It is an excellent nitrogen fixer.

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Taxonomy and growth

Genus
Alnus
Habit
tree
Life cycle
perennial
Foliage
deciduous
Woodiness
woody
Growth rate
vigorous
Height
25 m
Spread
8 m
Flower type
monoecious
Flower colours
green

Uses

Material uses

Plant part
Wood
Product or use
Timber, Firewood

Ecology and functions

Ecosystem niche
Canopy

Pioneer

This is an excellent pioneer species for re-establishing woodlands on disused farmland, difficult sites etc. Its fast rate of growth means that it quickly provides sheltered conditions to allow more permanent woodland trees to become established. In addition, bacteria on the roots fix atmospheric nitrogen - whilst this enables the tree to grow well in quite poor soils it also makes some of this nitrogen available to other plants growing nearby. Alder trees also have a heavy leaf canopy and when the leaves fall in the autumn they help to build up the humus content of the soil. Alder seedlings do not compete well in shady woodland conditions and so this species gradually dies out as the other trees become established[6].

Nitrogen fixer

Structure

The Italian Alder can be used as a support in polycultures. If the lowest branches are kept, the middle branches removed and the canopy kept high, Kiwis (Actinidia deliciosa) can be trained to grow up into the lower branches.

Windbreak

An excellent windbreak for maritime areas[4], it grows quite quickly and establishes well even in very windy sites[K]. Trees 5 years old from seed have reached 4 metres in height and are showing no signs of wind-shaping in a very exposed site in Cornwall[K].

Environment

Range
Europe - S. Italy, Corsica.
Habitat
Very rarely self-sown in Britain, but not naturalised.
Light
full sun
Shade tolerance
light shade
Water
high
Hardiness
Zone 6+
Soil textures
loamy, clay, heavy clay
Soil pH
acid, neutral, alkaline
Tolerances
high wind, maritime exposure, nutritionally poor soil
Wind
Yes
Maritime
Yes
Pollution
No
Tolerates Nutritionally Poor Soil
Yes
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

seed

Seed - best sown in a cold frame as soon as it is ripe and only just covered[3]. Spring sown seed should also germinate successfully so long as it is not covered[200, K]. The seed should germinate in the spring as the weather warms up. When large enough to handle, prick the seedlings out into individual pots. If growth is sufficient, it is possible to plant them out into their permanent positions in the summer, otherwise keep them in pots outdoors and plant them out in the spring. If you have sufficient quantity of seed, it can be sown thinly in an outdoor seed bed in the spring[5]. The seedlings can either be planted out into their permanent positions in the autumn/winter, or they can be allowed to grow on in the seed bed for a further season before planting them.

cutting

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

Can be propagated by seed indoor, or directly out and also with hard wood cuttings.

Seed Requires Scarification
No
Seed Requires Smokification
No
Seed Requires Stratification
No
Cutting Type
hard wood

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Thrives on poor and dryish soils, even on chalk, but prefers to be near water[2][3]. Prefers a heavy soil and a damp situation[1][2]. Grows well in heavy clay soils. Tolerates very infertile sites[2][3]. This species has a symbiotic relationship with certain soil micro-organisms, these form nodules on the roots of the plants and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[3]. A very ornamental tree[1], it is very fast growing, reaching 12 metres tall in 20 years in an exposed maritime position at Rosewarne in N. Cornwall[4]. Very tolerant of salt winds, it establishes rapidly in exposed positions[4]. According to World Economic Plants, the correct author of this species is (Loisel.)Loisel. and not Desf. as we have given here. However, since all our other sources have quoted Desf., we have decided not to alter it at this time (1999)[K].

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 32202/01/01

    ↩1↩2

  2. Bean. W. Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. Murray 32202/01/01

    ↩1↩2↩3

  3. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 32202/01/01 ISBN 0-333-47494-5

    ↩1↩2↩3↩4

  4. Rosewarne experimental horticultural station. Shelter Trees and Hedges. Ministry of Agriculture, Fisheries and Food 32202/01/01

    ↩1↩2↩3

  5. Sheat. W. G. Propagation of Trees, Shrubs and Conifers. MacMillan and Co 32202/01/01

    ↩

  6. pfaf

    Unresolved citation

    ↩

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