Lilacs are one of the most versatile shrubs. They form the genus Syringa and are members of the olive family characterised by producing clusters of trumpet-like flowers in a variety of colours during the spring.
The best-known variety is Syringa vulgaris, or the Common Lilac. It can be grown as a large shrub or a small tree up to 18 to 20 feet high. The flowers usually range from white to light lilac to mauve.
The Hungarian lilac (Syringa josikaea) is native to central and eastern Europe. It grows to 6 to 12 feet. The flowers are dark pink with a strong fragrance.
The Japanese lilac (Syringa reticula) is a relatively small tree. It grows to a height of 36 feet, and sometimes to 45 feet, making it the largest species of lilac, and the only one that is always a small tree instead of a shrub. The flowers are either yellow, white or off-white, and have a strong fragrance.
The Himalayan lilac (Syringa emodi) is also known as the "Late lilac" because it blooms much later in the season, sometimes as late as early summer. Growing to a height of about 9 to 11 feet, it is characterised by flowers that have a rosy-lilac hue.
The California lilac (genus Ceanothus) is not really a true lilac. These 50 to 60 species are actually in the buck-thorn family and is native only to North America. There are several varieties known as "creeping California lilacs" that are ground-cover.
Highland Park in Rochester, New York, in the United States has one of the largest collection of lilacs in the country. This location claims over 500 varieties and hosts a Lilac Festival each year in early May.