LILAC or PIPE TREE (Syringa vulgaris), a tree of the family Oleaceae. The genus contains about io species of orna mental hardy deciduous shrubs, native in eastern Europe and temperate Asia. They have oppo site, generally entire leaves and large panicles of small regular flowers, with a bell-shaped calyx and a 4-lobed cylindrical corolla, with the two stamens character istic of the order attached at the mouth of the tube. The common lilac is said to have come from Persia in the 16th century, but is doubtfully indigenous in Hun gary, the borders of Moldavia, etc. Two kinds of Syringa, viz. alba and caerulea, are figured and described by Gerard (Herball, 1597), which he calls the white and the blue pipe privets. The white is the common privet, Lig ustrum vulgare, which, and the ash tree, Fraxinus excelsior, are the only members of the family native in Great Britain. The "blue pipe privet" is the lilac, as both figure and description agree accurately with it. It was carried by the European colonists to north east America, and is still grown in gardens of the northern and middle states.
There are many fine varieties of lilac, both with single and double flowers; they are among the commonest and most beauti ful of spring-flowering shrubs.
The so-called Persian lilac of gar dens (S. dubia, S. chinensis var. Rothomagensis), also known as the Chinese or Rouen lilac, a small shrub 4 to 6 ft. high with intense violet flowers appearing in May and June, is considered to be a hybrid between S. vulgaris and S. persica—the true Persian lilac, a native of Persia and Af ghanistan, a shrub 4 to 7 ft. high with bluish-purple or white flow ers. Of other species, S. Josikaea, from Transylvania, has scentless bluish-purple flowers; S. Emodi, a native of the Himalayas, is a handsome shrub with large ovate leaves and dense panicles of purple or white strongly scented flowers. Lilacs grow freely and flower profusely in almost any soil and situation, but when neglected are apt to become choked with suckers which shoot up in great numbers from the base. They are readily propagated by means of these suckers. The dormant flower buds, which will not respond to a simple rise of temperature, are forced into development by the "hot water" treatment, thus en abling the grower to put flowering shoots on the market in the early months of the year.
Syringa is also a common name for the mock-orange.