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Little Known Lilacs

Originally published in the Ithaca Journal, May 2003
Column by Mary Hirshfeld, Director of Horticulture

Syringa Lilac
Syringa lilac The word "lilac" calls to mind opulent trusses of pale lavender, creamy white, or rich purple flowers wafting their heavenly scent about the May garden. The common lilac (Syringa vulgaris) is indeed a familiar, durable, and long-cherished garden plant that made its way with early European colonists to the United States in the early 17th century. Lilacs undertook the long sea voyage as bits of roots and shoots carefully wrapped in moist burlap or bundled in straw. The common lilac proved to be extremely accommodating and long-lived in the cooler parts of the United States, where it found the cold winter temperatures it needed to mature its flower buds. Today, gnarled old lilac trees frequently mark the site of a vanished house or barn foundation, now re-engulfed by woods.

The common lilac is native to southeastern Europe, extending northward into the Balkans. The rich array of lilac cultivars available to gardeners today can be attributed to the pioneering breeding work of Victor Lemoine, who started hybridizing selections of common lilac at his nursery in France in 1878. Many, perhaps too many introductions, often very similar in flower color and fragrance, made their way into European and American gardens. The excellent collection housed at Highland Park in nearby Rochester displays many of Lemoine's lovely hybrids and is a wonderful place to visit in May, at the height of lilac bloom season.

As lovely as the common lilac is when mature, it does have its drawbacks. Most selections get quite sizable within a few years and require regular pruning to stay within bounds, as well as diligent renewal pruning to maintain the young vigorous stems that flower most heavily. Most lilacs are also highly susceptible to mildew, a fungal disease that makes the foliage look dusty and white by mid-summer, as well as bacterial blight, an unsightly disease that blackens the young shoots, shriveling both vegetative and flower buds. However, some members of the genus Syringa are less susceptible to these problems than others and as such, make excellent garden plants.

Lilac species native to China, Korea and Japan made their way into European and American gardens later than the common lilac, arriving in the late 19th century after China's borders were opened to western trade. Three lovely, comparatively small-statured Chinese lilacs are readily available to gardeners today. Each, in the past, was sold under many names and cloaked in confusion. Taxonomists have recently simplified this long-standing nomenclatural morass by grouping them all together as subspecies of the hairy lilac (S. pubescens). The Manchurian lilac (Syringa pubescens ssp. Patula) from northern China and Korea, the Meyer lilac (S. pubescens ssp. Meyeri), found only in cultivation in China, and the little leaf lilac (S. pubescens ssp. microphylla) from northwestern China, are all easy-care plants rarely bothered by typical lilac diseases. All have a compact rounded form, leaves far smaller than those of the common lilac, and display masses of small lavender flower clusters in late May. They even offer a smattering of re-bloom in autumn.

The Manchurian lilac is most frequently represented by its cultivar 'Miss Kim', a wonderful plant that is more compact than the species, forming a densely branched rounded shrub five to six feet tall and wide. Smothered with icy blue flowers in May, this cultivar offers the added bonus of maroon fall color, an unusual feature among lilacs. 'Miss Kim' originated from seed gathered by E. M. Meader, near Seoul, Korea in 1947. Meader, on leave from his military duties for the day, went plant collecting, and discovered a dwarfed S. patula clinging to the rocky slopes of White Cloud Peak. Intrigued, he harvested all 12 seeds that remained on the plant in November. Two of the resulting seedlings exhibited the dwarf character of the parent, and one of these had glossy mildew-free foliage and deep red fall color. He introduced this one as 'Miss Kim' in 1954, through the New Hampshire Agricultural Experiment Station. Although slow to become widely distributed in the nursery trade, this selection is now easily found, and is one of the best lilacs for the home garden.

The little leaf lilac is a slow-growing, compact shrub reaching six to eight feet in height, and spreading even wider. Its pale lilac flower clusters appear in small quantities throughout the summer and into the autumn, giving it its second common name, four season lilac. In gardens, it is usually represented by the form 'Superba' whose profusion of clear pink flowers heads bloom from late May into early June. Like 'Miss Kim', 'Superba's' delicate foliage is quite mildew-resistant and takes on burgundy tints in autumn.

The diminutive Meyer lilac, found by Frank Meyer in a Chinese garden in 1909 while he was working for the USDA, for many years eluded discovery in the wild, leading to speculation that it arose in cultivation. This lovely, elegant shrub reaches four to five feet in height, with delicate leaves under two inches long, and delicately fragranced, lilac-colored flowers. The more compact form of this species, sold as 'Palibin' is a very choice garden plant; its flowers, slightly more pink than the species, will often reappear in autumn after their main late May display.

Interest in developing smaller-statured lilacs more suited to the confined spaces of most modern gardens has led to the introduction of several lovely "tribreds"-hybrids involving three species in their parentage. 'MORjos 060F', trademarked with the much more appealing name of 'Josee', was developed at Minier nursery in France in 1974. It reaches four feet at maturity and is valued for its tendency to re-bloom sporadically throughout the summer, after offering a lovely display of sweetly-scented bright pink flowers in June. 'Miss Canada', developed by plant breeder William Cummings in Manitoba, Canada is slightly larger, with rose-pink flowers borne in profusion in June. Another Cummings creation, 'Minuet', is a dense, rounded, five-foot-tall shrub with wide, dark green leaves and masses of pale lavender flowers in late May.

Bailey Nurseries in St. Paul, Minnesota is still adding to its series of diminutive "Fairytale" lilacs, developed by Neal Holland in North Dakota. Like their parents, S. pubescens ssp. microphylla 'Superba' and S. pubescens ssp. meyeri 'Palibin', these hybrids exhibit diminutive foliage on compact, delicately branched, four-foot-tall shrubs. 'Bailbelle', trademarked as 'Tinkerbelle', has dark red buds that open to fragrant, delicate pink sprays. 'Baildust', trademarked as 'Fairy Dust', sports pale pink flowers and sporadic summer re-bloom. And most recently, 'Bailsugar', trademarked as 'Sugar Plum Fairy', bears lilac flowers complete with the traditional heady lilac scent.

At the other end of the size spectrum are two arboreal lilacs-the Japanese tree lilac (S. reticulata ssp. Reticulata), and the Pekin lilac (S. reticulata ssp. Pekinensis). Until recently, these were considered to be two distinct species, and will most likely continue to be sold as such for some time to come; look for them as S. reticulata and S. pekinensis. The Japanese tree lilac is a lovely, small, tough-as-nails tree that can reach 20 to 30 feet in height, and is most frequently grown as a multiple-stemmed tree. Because of its relatively low mature height, drought and pollution tolerance, and ability to grow in almost any type of soil, it has become a favorite urban tree. Several lovely specimens can be seen on the downtown Ithaca Commons. Blooming in late June, well after other lilacs have finished up, it waves large, creamy, honey-scented plumes of flowers well above its large, dark green, heart-shaped leaves. In winter, its cherry-like polished bark, decorated with raised horizontal lenticels, makes a welcome ornamental feature. The Pekin lilac is similar to the Japanese tree lilac, although with slightly smaller flower heads, and glossy exfoliating bark that, at its best, resembles that of the paperbark maple.

Quite a number of tree lilac cultivars have been selected for improved form and floriferousness, as well as variegated and gold-colored foliage. 'Cameo's Jewel', 'China Gold', and 'Golden Eclipse' all offer variously gold-margined or gold-spotted young foliage, which usually matures to a muted green. 'Ivory Silk', an introduction from Sheridan Nurseries in Ontario, Canada, is narrower than most selections and begins flowering heavily at a very early age. It has been awarded the coveted Pennsylvania Horticultural Society's gold medal for its outstanding performance and ornamental characteristics. 'Summer Snow', from Schichtels' Nursery near Buffalo, NY, was selected for its smaller, more compact habit, which makes it an excellent choice for urban tree plantings. 'Morton', trademarked as 'China Snow' from the Chicagoland Grows Program, was selected for its tolerance of drought, extreme cold, and de-icing salts, combined with its narrow habit, and attractive, cherry-like bark. The parent tree was grown from seed collected by famed plant explorer Joseph Rock in China in 1926, and has reached 40 feet in height and 25 feet in width at its home in the Morton Arboretum in Illinois. 'Celeve's Select' produces unusually large foliage that provides dramatically bold texture in the landscape. 'DTR 124', trademarked as 'Summer Charm', is slightly smaller-statured, reaching 30 feet in height and 15 feet in width, and producing creamy flower heads in June. Many of these lilacs can be seen in the flowering shrub collection at Cornell Plantations' F. R. Newman Arboretum. Come enjoy their sight and scent!