DESCRIPTION OF THE STRAWBERRY TREE
I. Chessa, G. Nieddu - Dipartimento di Economia e Sistemi Arborei, Università di Sassari - Italy
BOTANICAL SPECIES: Arbutus unedo L.
HABITAT. The species originated in the coastal regions of the Mediterranean, in an area extending from southern Europe to western Asia and northern Africa, where the climate is mild and the summers dry. Together with many other tree and shrubby species typical of what is known as Mediterranean maqui, including cork trees and ilex oaks, wild-olive trees, myrtle and heather (Quercus suber, Quercus ilex, Olea oleaster, Myrtus communis, Erica arborea), it characterizes the Mediterranean landscape from sea-level to m 700-1000. The presence of the strawberry tree in some Atlantic regions and in Ireland could indicate anthropic introduction of the plant in Roman times when it was known and valued. Another hypothesis is that the species is indigenous as a relict of earlier mesophyll vegetation in existence before the last ice-age. Although it grows spontaneously in different types of soil it does best in loose, subacid subsoil in sunny areas not subject to frost.
PLANT. The plant is an evergreen shrub, although it can reach a size more typical of a tree (Æ 2.5 m, h. 5-8 m), as has been reported in Sardinia and Spain.
The leaves are simple, alternate, with a short stalk, elliptical or obovate in shape and of a size ranging from 4.5 to 12 cm. The lamina is smooth and coriaceous, dark green on top and light green underneath, the leaf margins entire or slightly dentate. The venation and young branches are a reddish colour.
FLOWERS. The strawberry tree has 6-10 cm inflorescences pendent at the ends of the branches, composed of 15-30 flowers. The hermaphrodite flowers have an ureolate corolla with five short teeth and are white or cream coloured, sometimes pink in the part exposed to the sun. Inside, they have 10 stamen with tomentose filaments and an ovary with 5 loculi and several ovules. The flowering period is from September to March, almost concurrent with the ripening of the fruit formed the previous year. Pollination is entomophilous, mostly by bees which produce a honey with a distinctive bitter taste.
FRUIT. The fruit is a small 4-8 g berry, varying in shape between flat and globular, sometimes showing a nipple. The skin is orange or reddish, spiked with several small tubercles. The flesh is amber-coloured and rich in sclereids. The number of seeds varies. The fruit is edible and is rich in sugar and vitamin C, but has never been considered, even in ancient times, as particularly good when eaten raw. Its Latin name unum edo, advising moderate consumption of the fresh fruit, reflects this.
USE. Besides being used to make bitter honey, an important product in areas like Sardinia, known for its antiseptic properties, the fruit can be eaten raw in small quantities, especially if mixed with other berries. It can be used to make jams, jellies, syrups, candied fruit and fermented and distilled drinks. The leaves and bark contain active principles of value to the herbalist, besides a large amount of tannin which can be used in industry, particularly in the production of dyes and in tanning skins and hides. In addition, the strawberry tree is an important source of food for the animals that live in the maqui. Recently, some interest in the plant has been shown by garden centres, which use both the whole plant and the cut-off branches. The species is resistant to fire and is used also in reforestation, the reinforcement of dunes and for soil protection.