(Alnus glutinosa (L.) Gaertn.)
Habitus
- it is a massive tree 20 – 30 m high, trunk straight, crown narrowly ovate, branches relatively thin
- bark is greenish-brown, shiny, with numerous transverse, narrowly linear, yellowish lenticels along the branches (and trunk)
- bork is dark gray to blackish, cracked into rectangular plates
- in very waterlogged habitats, it forms the so-called crutch-like roots, which grow from the side (from the lower part of the trunk) in an arc into the unstable marshy soil, thus stabilizing the woody plant
Buds
- the buds are built in a spiral, 5 - 8 mm long, inverted ovate, petiolate !
- the covering scales are two, brownish-purple, often reddened
Shoots
- they are triangular or rounded
- they are dark brown, later gray, sticky in spring, covered with lenticels
Leaves (assimilation organs)
- they are simple, inverted ovate, rounded at the apex, or notched, wedge-shaped at the base
- the edge is irregularly double-serrated to cut out
- top side is dark green, glossy
- lower side is light green, there are rusty hairs on the reverse side in the axils of the veins
- the stalk is 10 - 20 mm long
- they are sticky when young
Flowers
- it is a monoecious woody plant,with flowers of different sexes
- both male and female flowers are catkins, they are established as early as autumn
- it blooms in III – IV before leaf development
- ♂ catkins at the time of flowering are cylindrical, drooping, 4 - 7 cm long
- ♀ catkins are purple-brown, ovoid, up to 0.5 cm in size
- ♀ catkins later ripen into non-decaying cones
- the cone is 1,5 – 2,0 cm large, ovoid, green after ripening (October) dark brown, woody on a longer stalk
Fruits – seeds
- the fruit is an achene, 2 - 4 mm in size, bluntly pentagonal, with a wing on the sides
Extension
- more or less in the whole of Europe up to the Urals
- in Slovakia in floodplain forests, around rivers up to 740 (1,290) m above the sea level.
- It forms homogeneous and mixed stands lower with poplars and willows, higher with ash, elm and summer oak
- at the upper limit of occurrence, it is replaced by gray alder
Ecology
- it is a light-loving woody plant
- it grows on moist to waterlogged soils around rivers
- it is frost-resistant
- it also tolerates flooding
Significance
- As part of riparian vegetation, it has a soil protective, shore strengthening significance
- land reclamation and also as a pioneer tree
- it enriches the soil with nitrogen
- it is a high-quality wood, sapwood with a pinkish tinge, suitable for furniture production
