THE ACACIAS OR WATTLES.
Australia has contributed to southern California's tree flora a large number of forms of the acacia tribe, shrubs and trees of great variety and beauty of flowers and ever green foliage. They are hardy and perfectly at home, and are planted in such profusion as to be the commonest of all street and ornamental trees. The leaves are set on a branching pinnate stem, making them "twice compound" of many tiny leaflets, fascicled on the sides of the twigs, alternate on the terminal shoots of the season. The lacy, fern-like foliage of most acacias would justify the planting of them for this trait alone. But the abundant mass of bloom usually overwhelms the tree-tops, obscuring the foliage with a veil of golden mesh. Sometimes white, but oftenest yellow, the individual flowers are very small; but they crowd in button-like heads or elongated spikes, set close in axillary clusters. In their native woods these trees flower much less freely than in the land of their adop tion. The curling pods are in most species and varieties ornamental, as they pass through many color changes before they finally discharge their seeds.
Acacias compose a genus of four hundred species, and an untold and constantly increasing number of cultivated varieties. The continent of Australia has the greatest re presentation of native species. Others belong to Africa— tropical, northern, and southern regions. Asia, in its
warmer southern territory, and in southwestern China, has many native acacias. Tropical and temperate South America, the West Indies, Central America, Mexico, the southwestern region of the United States, and the islands of the South Pacific, all have representatives of this won derful and far-scattered genus. There is no country in terested in horticulture that does not grow acacias as orna mental shrubs and trees, even if they must be grown under glass the year round. In southern England the acacias, grown in open ground, and known as "tassel trees," attain good size.
Valuable lumber, tanbarks, dyes, perfumes, and drugs are yielded by acacias. Gum Arabic is the dried sap of several oriental species, particularly, Acacia Arabica, Linn. of Egypt and southern Asia.
As a rule, acacias have slender branches armed with spines. Often these are too small to attract notice, or to make the species useful as a hedge plant. All spines are modifications of the stipules at the base of leaf or leaflet. Thorns, however, are modified twigs, strong, stiff and sharp, often branched. The honey locust shows true thorns, not spines or prickles. The armament of canes of blackberry is only skin deep. This means of defence is best called "prickles."