The white willow (Salix alba) is a tree belonging to the Salicaceae family. In our country, it is very common, both in the wild and cultivated. Due to its ancient agricultural uses, it is also known as the pole willow, and in many regions, it is simply called the willow. However, not everyone knows that this tree is also rich in beneficial properties, which are contained in the bark of its branches and have been used in herbal medicine for centuries.
In this article, we will explore the botanical characteristics of the white willow, cultivation techniques, its properties, and the uses of its bark.
Description of the White Willow
The Salix alba is a deciduous tree, reaching heights of up to 20-25 meters. It develops a strong, straight trunk with a medium diameter of 60 cm, which can exceed 1 m in older specimens. It has rapid growth but is not very long-lived (80-100 years). The trunk’s bark is grayish with varying shades and begins to crack when young, with more prominent longitudinal fissures as it ages.
Branches and Bark
The white willow has a very broad and branched canopy with light and flexible branches that are fairly robust. The young branches, sometimes pendulous but usually erect, are pubescent, with brown-reddish buds and fine hairs. However, it is the bark of the branches that contains the most beneficial properties. This bark peels easily and has variable colors ranging from green-reddish to brown-reddish.
The leaves of the white willow are alternate on the branches and have very short petioles. They vary in shape from oblong to lanceolate-elongated, measuring 5 to 10 cm in length and typically 1 to 2 cm in width. The base tapers to a wedge, and the tip is long-acuminate. Both surfaces of the younger leaves are pubescent and shiny, becoming more or less glabrous as autumn approaches, except on the lower side and along the veins, which remain pubescent. The margin is serrated, with each tooth containing a gland with essential oil at its apex.
The white willow is a monoecious dioecious plant, bearing male and female flowers on the same plant but separate. Both types of flowers are clustered in catkins. The male catkins are located at the ends of small branches with reduced leaves, measuring 6-7 cm in length, with 2 stamens and yellow anthers with hairy filaments. The female catkins are shorter, with a glabrous, elongated, and pear-shaped ovary.
Flowering occurs in early spring, between March and April. These flowers are highly attractive to bees due to their abundant production of pollen and nectar. Male flowers have 2 glands that produce nectar, while female flowers have one.
Fruits and Seeds
The fruit of the Salix alba is a conical capsule, more or less sessile, with a smooth and glabrous surface. When mature, it opens into two valves, releasing numerous seeds covered with a dense white-silvery fuzz.
The Salix alba var. vitellina
This variety of white willow, also known as the golden willow, was once cultivated in the countryside to aid in agricultural activities. It has golden-yellow branches in spring, turning reddish in autumn. It is typically pruned back severely (coppiced), inducing the continuous growth of young branches used for making wicker for vine cultivation in pergola vineyards.
Natural Habitat of the White Willow
The white willow is naturally found throughout Italy, from sea level to altitudes of 1,200 meters. It prefers to grow near rivers or lakes, in particularly wet areas, and can withstand periodic flooding of watercourses.
How to Cultivate White Willow
In a domestic setting, white willow can be cultivated for ornamental purposes, such as a single tree in a large garden, although the weeping willow (Salix babylonica) is usually preferred for this purpose. Nevertheless, it is an excellent tree for creating hedges as it tolerates and responds well to repeated pruning.
However, before planting a willow in your garden, it is essential to assess the availability of water.
This tree can be successfully grown in moist soils where water availability is not a limitation. It does not tolerate summer drought well. It thrives in clayey and compact soils, where most other trees struggle. It also grows well in loamy and sandy soils, as long as the soil remains moist. The ideal soil pH ranges from 5.5 to 7.5, from slightly acidic to slightly alkaline.
Propagation and Planting of White Willow
In general, willow propagation is one of the simplest methods. The Salix alba is no exception. This tree is typically propagated in late autumn, just before the arrival of frost. If well-formed and healthy, you can cut branches that are 3-5 years old, choosing those with fewer secondary branches and straight growth (length of 1.5-2 m). These sections of the branch are called “cuttings,” and after collection, they should be kept in water for a few days.
Next, cut the top of the cuttings and sharpen the thick base, leaving the bark intact on one side up to the tip. At this point, the cuttings can be planted by burying them 30 cm into well-tilled and loosened soil for every 1 square meter. Mound some soil around the base and provide support. In spring, you will see new shoots growing from the cuttings.
Only the top shoots should be retained, while the central and lower shoots on the trunk should be removed. The retained apical shoots represent the scaffold (the future canopy) of the new tree.
White willow grows very quickly. Starting from this type of propagation, you can expect shoots over 1 m in length in the first year. After 4-5 years, you will have a well-formed small tree.
Consider the planting distance, maintaining a distance of 10-15 m from other trees or buildings.
If you don’t prefer this technique, you can also propagate willow by taking cuttings or by purchasing seedlings from a nursery.
Assuming you are cultivating a white willow tree in your garden, during the first few years after planting, cultural care should include irrigation, which should be abundant in spring and summer, especially during dry seasons. Once a year, in autumn, it is advisable to fertilize by amending the soil around the base of the tree with well-rotted manure or home compost.
How to Prune White Willow
White willow, like most other willows, tolerates significant pruning, including coppicing. However, in ornamental cultivation, it is advisable not to overdo pruning to avoid unsightly vegetative growth at the cutting points. Pruning should focus on keeping the canopy neat by removing dead, damaged, or misplaced branches. Pruning is typically done in autumn or winter after the leaves have fallen.
Pests Affecting the Tree
Several pests can attack the leaves and branches of the white willow. Among the main ones are lace bugs, the spotted lanternfly, scale insects, zeuzera pyrina (a type of wood-boring moth), red-belted clearwing (another wood-boring moth), gypsy moth, and the emerald ash borer.
Harvesting and Storing Bark
The bark of the white willow, rich in active compounds, is commonly used. It is harvested in October and November, when the leaves have fallen, from 2-3-year-old branches. The bark is cut with a sharp knife, peeled by hand, and cut into small pieces. It is then dried in the shade in a well-ventilated area. Once dry, it can be stored in paper or cloth bags.
Properties of White Willow Bark
The active compounds in the bark of white willow branches include tannins, resins, and the glycoside salicin, from which salicylic acid is derived. To understand its properties, consider that salicylic acid is the basis for the most famous drug in the world, aspirin. Salicylic acid is now synthesized in the laboratory, but it was initially extracted from white willow.
The main properties attributed to white willow include fever-reducing, anti-rheumatic, sedative, analgesic, and astringent properties. The bark of the branches is therapeutically useful for treating feverish conditions, rheumatic and muscular pain, flu symptoms, and gout disorders.
It is also indicated for promoting the normalization of gastric hyperacidity and the balance of digestive enzyme secretion.
For external use, due to its high tannin content, the bark of the tree exerts a strong astringent action on the skin and inflamed mucous membranes. It also promotes wound healing.
Uses of White Willow Wood
In forestry, white willow is not of great importance. Its wood is lightweight and not highly valued, mainly used in the paper industry for cellulose production. Another interesting use is in the production of charcoal for making black powder.
In households and herbal stores, dried bark from the branches is commonly used as a decoction, prepared using 2 g of dried material in 100 ml of water, to be taken in 2-3 doses during the day.
You can find it in herbal stores and specialized shops in the form of dried bark, supplements, bud-derived remedies, and mother tinctures.
Finally, the use of white willow is very interesting from an environmental perspective, as it is a perfect species for stabilizing riverbanks, eroded soil, and embankments, as well as for creating ecological stations, always near watercourses.
With the variety “vitellina,” this tree once played an important role in rural areas, especially in vineyard regions.