Poplar - Populus nigra
Poplar, common name for Populus, belongs to the Salicaceae family. It is a plant that has a very rapid growth and can reach up to thirty meters in height. Poplar originates in the Northern Hemisphere and boasts about thirty different species. In Italy it is widespread in the Po Valley, from where, passing through, it is easy to observe how this type of tree is particularly cultivated on large surfaces, especially in a position close to the course of the Po.
The characteristic lightness of its leaves, as well as its foliage, not excessively dense, and its very light color combined with the elegant and columnar shape found in many of its species, make the poplar particularly appreciated in the formation of avenues, both in parks and in gardens.
Again by virtue of its light foliage and its easy adaptability to full sun, the poplar it is also often used in the construction of screens or windbreak barriers. The trunk of the poplar is erect and gnarled with many branches. Its bark is white, or light gray in color which, over the years, intensifies towards a brown or dark gray tone.
Leaves, flowers, fruits
The poplar has oval, or rhomboid, or even lobed leaves, depending on the different species. They are about eight centimeters long and brown-green in color, shinier in the upper lamina and less in their lower surface. The male and female flowers are placed on different individuals arranged in separate catkins. The male catkins can reach a length of up to nine centimeters and have dense flowers and divided stamens. The female ones even reach twelve centimeters in length and have a yellow-green color, with much less dense flowers than the males. The fruits of the poplar, on the other hand, are small ovoid-shaped capsules that contain fluffy seeds inside them. Reached the right maturity the capsules let out the seeds opening in two parts, and these spread pushed by the wind. Fruits are not infrequently a cause of allergies to their pollen.
One of the most effective ways to grow the most common poplar species is to take cuttings from a branch, up to a foot in length, and plant them in normal soil in the fall season. A high percentage grow roots which in the following autumn are cut at the basal bud and subsequently planted again. This basal bud develops particularly vigorous vegetation which, within one or two seasons at the most, gives rise to an equally strong tree. In the nursery the cuttings of the usual length of thirty centimeters taken from the branches with one year of age are planted and after a year the grown specimens will be permanently planted.
Poplar prefers fresh and deep soils, rich in organic matter. It is important that the soil does not have excessive and continuous humidity.
Recommended after long periods of drought
Due to the poplar's preference for soils rich in organic matter, it is a good habit to enrich the soil at the foot of the plant with valid organic fertilizer, at least once every two years.
Particularly insidious and dangerous for the life of the poplar is chrysomela, which gnaws at the leaves causing them to deform and can often lead to the death of younger specimens. Then there is the poplar weevil larva which acts by digging tunnels inside the branches and causing the less resistant plants to dry out. Finally, an often harmful parasite is the woolly aphid, which attacks the shoots and covers them with a flaky substance, also causing unpleasant bullous growths both on the branches and on the bark.
Poplar: Other species
Other common species of poplar are black poplars, with gray but not black bark and leaves that have a beautiful copper color in spring. The balsam poplar, with the characteristic of having winter buds which, at the moment of opening, in spring, spread a strong and pleasant scent.
White and gray poplars: the first, populus alba, has white bark and underside of the leaves, the second, tending precisely to gray, reaches large dimensions.
Finally we remember the poplar tremulous, so called for the incessant and fascinating trembling of the leaves that move even in the presence of a slight breeze.