Lilacs (Syringa) are a genus of plants, in the family Oleaceae. They are native to Europe and Asia. Lilacs range in size from large shrubs to small trees, approximately 2-10 m tall. The leaves are opposite, deciduous, and in most species simple and heart-shaped, but pinnate in a few species (e.g. S. laciniata, S. pinnatifolia). The flowers are produced in spring, each flower about 1 cm diameter, white, pale pink or more generally purple, with four petals. The flowers grow in large panicles, and in several species have a strong fragrance. Flowering starts after 80-110 growing degree days.
Cultivation and uses
Lilacs are popular in parks and gardens throughout the temperate zone. In addition to the species listed above, several hybrids and numerous cultivars have been developed. The term French lilac is often used to refer to modern double-flowered cultivars.
Lilacs flower on old wood, and produce more flowers if unpruned. If pruned, the plant responds by producing fast-growing young vegetative growth with no flowers, in an attempt to restore the removed branches; a pruned lilac often produces few or no flowers for one to five or more years, before the new growth matures sufficiently to start flowering. Unpruned lilacs flower reliably every year. Despite this, a common fallacy holds that lilacs should be pruned regularly.
Lilac bushes can be prone to powdery mildew disease, which is caused by poor air circulation.
A pale purple color is generally known as ‘lilac’ after the flower.