The Content Of The Article:
- Appearance and growth
- Location and ground
- Important species and varieties
- Diseases and pests
The alder (Alnus), also called Eller or Else, belongs to the family of birch family (Betulaceae) and is widespread throughout Europe; it is missing only in northern Scandinavia and Iceland. With a maximum age of 120 years and the high light requirement that characterizes the young trees, it can not compete in the long term with other trees in the long term. However, it has found its niches on extremely wet or temporarily flooded sites. Her predilection for humid, swampy areas has earned her the dubious reputation in medieval folk belief of being in touch with witchcraft.
Appearance and growth
In Central Europe, three alder species are native: the black alder (Alnus glutinosa), the gray alder (Alnus incana), also known as Weißerle, and the green alder (Alnus viridis, syn. Alnus alnobetula). Depending on the species, the alder occurs as a high deciduous tree, as a multi-stemmed wood or as a shrub. The black alder usually grows with an annual increase of an impressive 20 to 40 centimeters to a 30 meter high, impressive tree. Its trunk runs straight up to the treetop and the crown looks like a loosely designed pyramid. Even faster is the Weißerle. With an increase of 30 to 60 centimeters per year, it forms multi-stemmed, cone-shaped woody plants that grow four to eight meters wide and about ten meters in size with branches growing slightly diagonally upwards. Rarely does it present itself in a classically sturdy tree form. The smallest is the green alder. It is not much taller than three meters as a broad shrub.
Green alder (Alnus viridis, syn. Alnus alnobetula)
The alder is a deciduous wood, its leaves grow alternately. Concise are the female fruit stands, which lumbered as a cones over the winter remain on the tree and adorn the bald young shoots of black and gray alder.
Location and ground
The alder loves sunny places, but also copes in partial shade. It has no special requirements, but preferably nutrient-rich, fresh to wet and slightly acidic soils.
Nurseries offer alders as Heister (bare root) or as solitaire with bales or in containers. Autumn is the best time to plant root-bare goods. The planting hole should always be so wide that the roots around it do not hit the ground. Solitary with a well-rooted bale can be planted year-round in frost-free weather. Autumn is also the best time for planting, since in the spring, as a deciduous shrub, they put a lot of power into the sprouting leaves. An alder grows well when the planting hole is about twice as large as the root ball and it is refilled with the excavation without gaps after insertion. Sludge and easy grounding of the earth helps.
The alder does not need winter protection. It is well adapted to our climate. Alders love wet to wet places. In a rather dry garden soil, the trees must be regularly generously poured in the absence of rain and heat.
Young trees of black and gray alder need a planting cut before moving into the garden. As a rule, a nursery accepts this part when selling it. If this is not the case, you have to cut in the crown by about a third. Thereafter, the scissors should only be used to remove dead and diseased wood and branches that interfere with each other or massively disturb. This correction cut is best done in late summer. Since the green alder is a cut-friendly shrub, it can be lighted in the spring without any problems.
In Venice, the trunks of the alder tree served as sturdy supports for the famous Venetian stilt houses. Because the wood tolerates persistent. This is a characteristic why the black alder is especially chosen for the planting of ponds or small lakes. In addition, one sees black and gray alder in large gardens and parks often with their auskausste branches as formative Solitärgestalten. As the black alder hardly forms lateral roots, it can be well planted with perennials and grasses that tolerate shadows. The Grünerle is different. It forms a dense network of roots and secures slopes in a pretty way.
Important species and varieties
The black alder can be easily recognized by its sticky leaves during spring shoots. In summer, it bears up to ten inches long, roundish-shaped leaves with a sawn edge. The upper side is shiny dark green, the underside light green. The hairless leaves stick to the tree for a long time and do not wear autumn colors. Their flowers drift from March as red-brown kitten.From autumn, the fruit stalks hang as one to two centimeters large hairless cones on long stalks on the branches. The bark of young trees is dyed greenish brown, glossy-smooth and falls with numerous transverse cork pores. It develops in older trees to a dark gray, divided by cracks into small, angular pieces Schuppenborke. The heart-shaped root system of the black alder lack strong lateral roots. It also has few fine roots below the soil surface and at the ends of the deep vertical roots. The air exchange takes place through large cork pores at the root base and at the near-surface fine roots. In addition, the black alder root nodules, pinhead to apple-sized swells of short, thick, forked roots. They harbor a symbiotically alder living and nitrogen-binding bacterium.
Bamboo bark (Alnus glutinosa 'Imperialis')
A recommended variety of black alder is the bamboo alder (Alnus glutinosa 'Imperialis'), a six to eight meter small, slow-growing tree or large shrub with slender, funnel-shaped emerging trunk and loosely elegant overhanging branches, reminiscent of a bamboo. The leaves are very fine and filigree. Their three to four irregular, narrow and on more than half of the leaf blades incised lobes often hang over arched and are curved outward.
The gray or white alder (Alnus incana) owes its name to its pointed leaves. These are covered on the bottom with a white-gray felt. Their yellow kittens flower very early and show up already in February. In contrast to the black alder their cones are hairy. They sit directly or on short stems on the branch. The bark is gray-shiny and smooth, the roots are flat and reach far. In root injuries, the Grauerle forms foothills.
The gold alder (Alnus incana 'Aurea') grows either as a small tree with a narrow crown or as a large shrub with several trunks. Both growth forms of the variety are about twelve feet high. The young shoots sprout in the spring light yellow and are also drawn reddish; In winter, the branches bear the color apricot yellow to brown orange. The leaves emit yellow when they are expelled, later they turn yellow-green. Male kittens glow in a gorgeous orange to coppery red. The other features correspond to those of the type.
Golderle (Alnus incana 'Aurea')
The green alder grows as a small shrub with spreading branches. It is usually not much higher than three feet and carries on elastic, cut-tolerant branches dark green leaves of egg-shaped, slightly pointed shape. While the male catkins are hairy and hanging on the twigs, the females on the twigs are standing in reddish tufts. The root system extends flat woven over a large area. The bark / bark is finally gray-brown, at the trunks it goes into the black.
The black alder multiplies in nature with the help of its seeds. The green alder, however, by Wurzelausläufer and so-called sinkers, ie low-hanging, ground-level branches that rooted in contact with soil. The Gray Alder has a choice: it can multiply both generatively by seeds and vegetatively by Wurzelausläufer.
Diseases and pests
The alder is well prepared as a native tree against diseases and pests. As a rule, she does not need care in this regard.