Forests are either simple, in which the trees are about the same height and form a single canopy (level), and complex, consisting of two or more layers, one above the other. In the first stage (upper canopy) are high mature trees, in the second — the younger and less high (adolescents) and in the third — shrubs (undergrowth).
The more light-requiring species that make up the upper canopy, and the richer the soil, the denser and more varied undergrowth: hazel, honeysuckle, euonymus on loamy sands and wet sands, buckthorn in the lowlands, broom in the southern forests.
In the Far East can be found shestiyarusny stands: the top tier — Korean pine mixed with birch 30-36 m in height, the second tier — lime, and the third — maple, walnut, Amur velvet, black cherry, and the fourth — the Amur lilac the fifth — two species of maple (high undergrowth); sixth — hazel (hazel), jasmine, euonymus (low undergrowth).
Of the most common understory species in central European part of the country should be called hazel. Hazel Shade-tolerant rather well reproduced shoots from the stump, root suckers and slips, but relatively demanding on soil fertility, does not tolerate dryness and salinity. The presence of the undergrowth hazelnut ^ as lime, is a sign of a more or less fertile soils. Hazel nuts are rich in oil and edible.
In Siberia, the Caucasus, Central Asia, the Altai-growing sea buckthorn shrub 2-3 m of sea-buckthorn berries are rich in vitamin C. Sea buckthorn oil contains pro-vitamin A (carotene) and is used for burns, frostbite, with radiation injuries. Seabuckthorn is very light-requiring, demanding soil and grows poorly on heavy clay soils.
From Kuban to Kolyma and the Kuril Islands from late July until late winter in our woods rdeyut red bunches of rowan — treat thrush and upland game. Rowan tree grows in any soil, except for saline and torfyanobolotnyh. No less known and yellow acacia, which is often used for hedges, as it tolerates a haircut. Under natural conditions, yellow acacia widespread in southern Siberia, the Altai, Central Asia and the Trans-Baikal. It is not sensitive to frost and grows in any soil. With all the positive qualities of this shrub has one significant drawback — no birds build their nests in it.
In our country, there are 37 species of wild blackberries. It grows in damp places, on the banks of rivers in the European part of the country, but especially a lot of it in Siberia.
Singly or in groups in thickets, in the forest, on the banks of rivers, in sparse forests growing hawthorn bush. In the thickets of his birds nest.
Autumn in the oak and linden forests noteworthy small shrub with branches that hang beautiful red-white-fruit earrings with a black spot. This warty euonymus. He rarely found in birch and pine forests north of Moscow and Gorky and does not grow beyond the line Pskov — Yaroslavl — Kirov. Warty euonymus — guttonosnoe plant: the roots it contains percha.
Elderberries with its thick light red tassels and viburnum berries with red berries on long stalks away visible even in the dense undergrowth. Kalina — a tall shrub, grows in moist soils of large forests, particularly in oak, in clearings, ravines and along rivers and streams. Keep up with it in the middle band in August. Buckthorn (her black berries) and wolf bark (bright red) are almost universally found in the undergrowth of deciduous forests.
Throughout the forest zone of Russia extended evergreen shrub juniper. It blooms in spring, fruit (shishkoyagody) mature in the second year, in September, they contain essential oil, malic acid, acetic acid and formic acid, and 40% of sugar, vitamin C, and wax.