Alnus incana
| Alnus incana | |
| Light: |   |
| Moisture: |    |
| Hardiness: | 2 |
| Soil pH: | 5.6-8.4 |
| Height: | 59' |
| Width: | 16' |
| Speed: | Fast |
| Blooms: | Late Winter-Early Spring |
| Open Woods Forest | |
| Native to: | |
| Nitrogen Fixer | |
| Tea: | Yes |
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Alnus incana (common name: grey alder)
Propagation: Seed - best sown in a cold frame as soon as it is ripe and only just covered[1]. Spring sown seed should also germinate successfully so long as it is not covered[1][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[2]. 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.
Cuttings of mature wood, taken as soon as the leaves fall in autumn, outdoors in sandy soil.
Cultivation: Prefers a heavy soil and a damp situation[3][4]. Grows well in heavy clay soils[4]. Thrives in drier soils than many other members of this genus[1]. Tolerates very infertile sites[1].
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[1].
Range: Europe. Introduced in Britain[5].
Habitat: Mountains, especially on poor soil[5][6].
Usage: This species fixes atmospheric nitrogen and is also tolerant of polluted soils, it can be used for land reclamation, especially on coal tips[1].
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[K].
The bark and the fruits contain up to 20% tannin[7][8][9].
Wood - light, soft, fairly elastic, easy to split. Used for clogs, bowls, woodcuts etc. Much valued by cabinet makers[7][8].
Pollinators: Wind
Soil: Can grow in medium and heavy soils.
Wind: Tolerates maritime wind exposure
Flower Type: Monoecious
Heavy Clay: Grows in heavy-clay soils.
Also Known As: Betula alnus incana.
Links
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Huxley, Anthony. The New Royal Horticultural Society Dictionary of Gardening. MacMillan Press, 1992.
- ↑ Sheat, Wilfrid. Propagation of Trees, Shrubs and Conifers. St Martin, 1948.
- ↑ Chittendon, Fred. RHS Dictionary of Plants. Oxford University Press, 1951.
- ↑ 4.0 4.1 Bean, William. Trees and Shrubs Hardy in Great Britain. Murray, 1981.
- ↑ 5.0 5.1 Clapham, Arthur and Tom Tootin, Edmund Warburg. Flora of the British Isles. Cambridge University Press, 1962.
- ↑ Tutin, Tom et al.. Flora Europaea. Cambridge University Press, 1964.
- ↑ 7.0 7.1 Uphof, Johannes. Dictionary of Economic Plants. Weinheim, 1959.
- ↑ 8.0 8.1 Usher, George. A Dictionary of Plants Used by Man. Constable, 1974.
- ↑ Rottsieper, E. Vegetable Tannins. The Forestal Land, 1946.