Majority of lilacs are shrubs, while a few of them are more tree-like – like small trees. Many wonder if there is really any difference between shrub-like lilacs and those that are like smallish trees. Usually, trees have a solitary stem and they are relatively tall. However, you can also prune shrubs to just a single stem. Therefore, the two terms – shrubs and trees actually overlap.
In addition to the stem and height, the foliage of shrub lilacs and tree-like lilacs differs. The common lilac or Syringa vulgaris bears relatively big simple, opposite leaves without any tooth. However, the leaves of some not so familiar lilac species may possibly be small, lobed, compound and even feathered. The individual lilac flowers, which are also known as florets, are usually aromatic. Normally, the florets comprise four petals. While the flower itself is comparatively small, they make up large clusters, which, in botanical terms, are known as thyrses. These flower clusters are also known as racemes or panicles. Despite the florets being small, the overall effect of thyrses is ostentatious. The flowers may be single or double. When we say double flowers, it means that every lilac floret or individual flower comprises more than the typical four petals. On the other hand, when we describe a flower as multipetals, we actually refer to single flowers having divided petals. In addition, the petals may also be elongated, rounded, folded, pointed, or curved or cupped forward or backward (also known as reticulated). When the flowers wither away, they leave behind dry, brown-hulled capsules that contain the seeds.
Lilacs or Syringa is a member of the family Oleaceae, which also includes the olives. Other familiar garden plants that belong to this plant family include jasmine, forsythia, privet and ash. All these plants bear flowers having four petals. Lilacs are so closely related to privet that they can also be grafted onto the latter species. There was a time when botanists actually classified lilacs and privets (Ligustrum) together. Even the flowers of privet look similar to the small, white lilac blooms. Lilacs are members of the genus Syringa, which derives its name from Syrinx, the nymph who, according to Greek legend, was a follower of Artemis and transformed into a reed to get away from the passionate advances of Pan. Albeit in an indirect manner, Greek mythology says that Pan opted for the same reed – the transformed Syrinx, to produce his Pan pipes. Therefore, the name Syringa implies that the stems of the plants belonging to this genus are hollow and reed-like. This aspect of the lilac plants has led it to be named as the pipe tree.
The genus name Syringa is also confusing, as the mock orange (botanical name Philadelphus lewisii) is also commonly known as syringa. At the same time, the name lilac is also used to describe some plants that have no relation whatsoever with lilacs or Syringa, but produce bunches of bluish blooms. These plants include a few forms of the Hardenbergia (vine lilac), Ceanothus (California) and Hebe hulkeana (New Zealand lilac).
Lilacs of Syringa are very well-liked shrubs and are extensively grown in gardens and parks in all places having temperate climatic conditions. Over the years, breeders have developed many hybrids and cultivars, which are also extremely popular. We often hear the term French lilac and it denotes the modern-day lilac cultivars that produce double flowers. They are called French lilacs because the initial cultivars were developed by the noted French breeder Victor Lemoine. Lilacs grow best when grown in well-drained soils that are alkaline or chalky in nature. These shrubs bloom on old wood or mature shrubs and bloom copiously if the plants are not pruned. However, when the plants are pruned that led to vigorous new vegetative growth, but their flower production decreases considerably. The rapid vegetative growth of the plants aim at restoring the branches removed during pruning. It has been found that lilac shrubs are susceptible to powdery mildew disease.
The timber of lilac shrubs or trees is not only very hard, but also amongst the densest wood found in Europe. It is close-grained and diffuse-porous. Usually, the sapwood of the plants is cream hued, while the heartwood comes in a variety of brown and purple shades. Traditionally, the timber of lilac shrubs and trees has been used for making musical instruments, engraving, knife handles and other purposes. Lilac wood may become curvy or twisted when it is dried. When this occurs, the wood often comes apart in the form of slender sticks.
Lilacs are basically shrubs or smallish trees that grow up to a height of anything between 2 meters and 10 meters (6 feet 7 inches and 32 feet 10 inches), while the diameter of the stems range from 20 cm to 30 cm (7.9 inches to 11.8 inches). The lilac leaves appear opposite to each other on the branches and sometimes they may also appear in whorls comprising three leaves. The shape of the leaves vary from simple to wide lanceolate and heart-shaped. A few species, such as S. pinnatifolia and S. protolaciniata, the leaves may be pinnate. Lilacs bloom during spring and each flower measures about 5 mm to 10 mm (0.20 inch to 0.39 inch) in diameter and having a four-lobed corolla. The corolla tube is slender, measuring anything between 5 mm and 20 mm (0.20 inch to 0.79 inch) long. The flowers are bisexual, containing both male and female reproductive parts – each flower has a productive stamen and stigma.
Usually, lilac flowers come in different shades of purple and sometimes in pale purple or lilac hues. However, several plants produce flowers whose colors vary from white to light yellow to pink. Some plants also produce dark burgundy colored flowers. The flowers appear in large panicles and many lilac species produce potently aromatic blooms. Subject to the lilac species, the blooming season varies between the mid-summer and beginning of spring. The fruits of plants belonging to this genus are dry, brown-hued capsules that split open into two when they are mature and release seeds each having two wings.
Many of you may possibly be aware of the fact that botanical classification is akin to the manner in which the Chinese name humans. In this system, the surname or genus name comes first and it is followed by the name of the species. In the case of lilacs, the genus name Syringa comes first and followed by the species name, which is often descriptive, vulgaris. Syringa vulgaris is the name of the common lilac. The term vulgaris denotes the English word vulgar, or common. Similarly, the lilac species called Syringa x persica hints to the reported origin of this species – Persia. Likewise, S. pinnatifolia denotes that the plant has feathered or pinnate foliage. Apart from being descriptive, a number of lilac species has been named to honour certain people. For instance, the lilac species S. josikaea has been named thus to honour the Baroness Rosalia von Josika, a reputed botanist who was responsible for brining this lilac to the scientific community’s notice.
However, the botanical names of interspecific hybrids, which are actually crosses between different lilac species, often confuse people. When a hybrid is developed by crossing two lilac species, the name of the female parent of the hybridized plant comes first, the letter x comes in the middle and it is followed by the name of the male parent. In case, the hybrid has several progenies, the name of the new species may be created. Nevertheless, the new name should have the letter x before it. Hence, the hybrids developed by crossing S. villosa x S. reflexa have been named S. x prestoniae – the naming of this species was done to commemorate Isabella Preston. When this botanist developed an opposite cross with S. reflexa as the female parent, the new hybrid was not equally outstanding.
Thus, many may be wondering how the new hybrids developed by crossing three or even more lilac species are named. Such plants are often known as tribreds (developed by crossing three species) or multibreds (developed by crossing more than three species). These type of hybrids may actually not be designated any particular species name, for instance, Syringa “Bailbelle”. In fact, this particular lilac cultivar has also been assigned a trademark name Tinkerbelle TM. These days, registered or trademarked names are becoming more and more common and, besides giving a scientific name to a particular cultivar, these names also help the breeder to earn revenue for using the plant’s name.
Then again the cultivar names of different cultivated varieties are enclosed by quotation marks, for instance “Agincourt Beauty” is a cultivar of S. vulgaris. When you visit a nursery, it is likely that you will only be seeing the species or cultivar names of the plants. Therefore, it is essential for you to know these names so that you are able to identify the specific plants. It is important to get the cultivar names approved and also register those names to make sure that two cultivars do not share the same name. While naming the cultivars, you should ensure that the names should be descriptive and have an appropriate length following the guidelines mentioned above. In other words, this denotes that the name of the plant is same everywhere and is not shared with other plants.
Growing garden lilacs
Lilacs in containers
Renovating and moving lilacs
Pests and diseases of lilacs