Family: SALICACEAE
Willows generally use large amounts of water, will grow in waterlogged soil and have root systems that have been known to reach out as far as 50 m laterally in search of moisture and nutrient. For this reason, they are extremely good trees for sheet, gully and slump erosion and for salinity control, but should not be planted close to gardens, septic systems and orchards. Willows will generally tolerate prolonged periods of flooding. They are fast growing, yield a soft, light timber, and provide useful fodder for stock. They grow best in an open, unshaded situation.
There are over 300 species of willow, having the widest natural geographical distribution of any tree - right across the northern hemisphere and South America and South Africa. About a dozen species will grow into timber - sized trees, the others remain as small trees or shrubs. A great number of hybrids have been produced in natural populations and many more have been obtained artificially. Willows are very fast growers and many have foliage which is edible to livestock. (Weeping willow - 15.9% crude protein, 2.9% crude fat, 18% crude fibre, 1.6% calcium, 0.27% phosphorous and 10.2% ash.) "New Zealand trials have shown the hybrid willow to produce more than 30 tonnes of dry matter yield per hectare, whereas good grass or lucerne stands yield only 10 to 15 tonnes per hectare. Tree crops however also allow grass to grow beneath." (Ref. Thamo. A. "Fodder Trees" from "Trees for Farms").
Willows can be either cut and carried to stock, established as lock up self forage systems or in the case of the weeping trees, stock can only trim what grows down to their reach.
Willows are extremely good bee forage plants, providing both nectar and pollen, at a time when few plants are flowering. They may also have medicinal properties. It is said that the American Indians were able to lower fevers by drinking an infusion of willow tree bark. The bark has also been used traditionally as a cure for rheumatic complaints. One of the active ingredients of willow bark is salicin which relieves pain and stiffness in the joints. Acetyl -salicylic acid, better known as aspirin, is one of its derivatives.
Willows strike readily from cuttings taken at any size, in fact so strong is the rooting hormone that it surpasses commercial rooting powders as a means of encouraging cuttings from other plants to establish roots. Willow cuttings placed in a bucket of water will develop roots after about a week. Any cuttings from other plants, allowed to soak in this same water overnight, will have greatly increased chances of developing roots. Those cuttings should then be placed in cutting beds in the usual manner.
Young willows should be planted so their roots are above the winter groundwater table. The best sites for planting willows are summer moist or sites not far from the water table. Willows may need summer irrigation until their root systems reach ground water. Trees can be planted reasonably close (2 m) if they are to be kept cut or up to 5 m apart for full sized trees.