SYRINGA, LILAC, in botany, a genus of the monogynia order, belonging to the diandria class of plants. There are two species; both of them deciduous flowering shrubs, adorned with oval, heart-shaped, and spear-shaped simple leaves, and large bunches of odoriferous small funnel-shaped flowers, white, blue, and purple, in the different varieties. They are all hardy plants; and though natives of Persia, will bear the severest winters. They are easily propagated, by seed, suckers, or layers.