The fragrance of lilacs in May evokes memories of Grandma's garden and nostalgia for springs gone by. Beyond their distinctive perfume, lilacs have other easy-to-identify features. Lilacs are a part of the plant family Oleaceae, the olive family, which also includes forsythia, jasmine and ash. Lilacs are native to Eastern Europe and regions of Asia from Afghanistan to Japan. They can live for hundreds of years, flourish in nearly any soil and tolerate harsh weather, blooming heartily year after year.
Observe the Lilac's Features
Go to an area where lilacs grow -- a garden, backyard, park, botanical garden or garden center -- in the spring. Lilacs and tree lilacs are easiest to identify during their blooming season, from May to June.
Touch, observe and examine all the parts of the lilac plant, from the leaves, flowers, bark and branches to the lilac's height and growth habit. It helps to have a book about lilacs or a garden plant guidebook to help identify specific lilac species and hybrids.
Observe the leaves. Lilacs have smooth-edged leaves that grow in pairs directly opposite each other on the branch. They are medium-to-dark green, often simple and can be heart-shaped, oval with pointed tips, lance-shaped or small. During the autumn, some lilac species become bare early since the leaves quickly yellow and drop off.
Feel, smell and look at the showy flower clusters. They may be fragrant with a sweet, dewy or spicy perfume. The light lilac-purple color is most common, but lilac flowers can also be pinkish, bluish, purple, violet, magenta, white or bi-color. The edible, four-petal florets can be single or double. Are the petals pointed, rounded, cup backward or forward? The mature fruit is a dry brown capsule that splits in half to reveal the seeds. Japanese tree lilacs have frothy, creamy-white flower clusters.
Examine the bark. Lilac bushes have mottled, medium-brown bark that easily peels off in vertical strips as it matures. Notice the spiral growth pattern on the older branches. Green lichen might be growing on the branches. Lichen have a helpful, symbiotic relationship with lilacs; it's a sign of clean air. If the bark is ornamental, glossy red-brown and ridged with horizontal lenticles (lines), like cherry tree bark, the lilac is a Japanese tree lilac.
Examine the growth habit of the lilac. Is it a vase-shaped shrub or a rounded tree? Dwarf lilac bushes grow only 4-to-6 feet tall. Regular lilac shrubs grow 8-to-12 feet tall. If the lilac is a small tree about 15-to-20 feet tall with dark green leaves, it's most likely a Japanese tree lilac or other tree lilac.
Look for a Syringa vulgaris, or common lilac, if you want the classic garden lilac. Native to southeastern Europe, the May-blooming common lilac is the base for hundreds of lilac cultivators and hybrids, including hyacinth lilacs, Preston hybrid lilacs and the Lemoine French hybrids. This lilac has a tendency to sprout out many shoots, or suckers, at its base.
Try Japanese tree lilacs and Pekin lilacs (Syringa reticulata and Syringa pekinensis) if you are considering a beautiful but hardy and disease-resistant, small, flowering tree. Native to northern Japan and China, respectively, these lilacs bloom in June and are ideal for landscape or street plantings. Good varieties: Ivory Silk and Chantilly Lace Japanese tree lilacs or China Snow Pekin lilac.
Plant the naturally dwarf Meyer lilac, Syringa meyeri Palibin, if you want a lilac that works well as a compact, dense hedge or shrub border that needs little pruning. Powdery-mildew resistant, it grows 4-to-6 feet tall with small leaves and masses of fragrant, pinkish-purple flowers that bloom in late May.