|Syringa subsp. var.||Lilac|
They are deciduous shrubs or small trees, ranging in size from 2–10 m tall, with stems up to 20–30 cm diameter. The leaves are opposite (occasionally in whorls of three) in arrangement, and their shape is simple and heart-shaped to broad lanceolate in most species, but pinnate in a few species (e.g. S. protolaciniata, S. pinnatifolia). The flowers are produced in spring, each flower being 5–10 mm in diameter with a four-lobed corolla, the corolla tube narrow, 5–20 mm long; they are bisexual, with fertile stamens and stigma in each flower. The usual flower colour is a shade of purple (often a light purple or lilac), but white, pale yellow and pink, and even a dark burgundy color are also found. The flowers grow in large panicles, and in several species have a strong fragrance. Flowering varies between mid spring to early summer, depending on the species. The fruit is a dry, brown capsule, splitting in two at maturity to release the two winged seeds.
Lilacs are popular shrubs 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, thanks to the work of prolific breeder Victor Lemoine.
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. If pruning is required, it should be done right after flowering is finished, before next year's flower buds are formed. Lilacs generally grow better in slightly alkaline soil.
Lilac bushes can be prone to powdery mildew disease, which is caused by poor air circulation.
|Standard Cyclopedia of Horticulture|
Syringa (of doubtful meaning; probably from syrinx, pipe, because pipes are made from the straight stems of Philadelphus by removing the pith, and the name Syringa had been originally applied to Philadelphus but was transferred to the lilac. Philadelphus is still popularly called Syringa). Oleaceae. Lilac. Ornamental woody plants grown chiefly for beautiful and showy often fragrant flowers.
Deciduous, rarely evergreen (S. sempervirens), shrubs or small trees: lvs. opposite, entire or rarely pinnate, exstipulate: fls. in panicles; calyx small, campanulate, 4-toothed; corolla salverform, with cylindrical tube and 4-lobed limb; stamens 2; ovary 2-loculed: fr. a leathery, oblong or oval caps., loculicidally dehiscent, with 2 winged seeds in each locule. (Fig. 3758.) In S. sempervirens the caps. is fleshy, one-seeded, and drupe-like, though dehiscent.—About 30 species from S. E. Eu., to the Himalayas, N. E. Asia, and Japan.
The lilacs are mostly large shrubs with bright green medium-sized foliage and with large showy panicles of lilac, purple, or white flowers followed by brown insignificant capsules. They are among the most popular and ornamental flowering shrubs, and hardly any garden or park is found without them. The fragrance of the common lilac is very sweet, as also of S. oblata and S. pubescens. The strong odor of S. chinensis is not agreeable to everyone. S. villosa and S. Josikaea are almost scentless. S. amurensis and its allies have only a slight odor similar to that of the privet. Almost all species are hardy North, but S. emodi is somewhat tender; also, S. pekinensis is not quite so hardy as S. amurensis and S. japonica. The lilacs are very showy in bloom, especially when massed in groups, and groups as a rule are the more effective the fewer different varieties they contain. The mixing of species and varieties differing in habit and blooming season only spoils the effect, and so does too great a variety of colors. S. japonica is the only real tree of the genus; it attains a height of 30 feet. S. vulgaris, S. amurensis, and S. pekinensis sometimes grow into small trees or at least large shrubs 10 to 20 feet high. S. persica is one of the smallest species and seldom exceeds a few feet. The first in bloom are .S. affinis and S. oblata, followed closely by S. vulgaris, S. chinensis, S. pubescens, S. Julianae, S. persica, S. villosa, S. emodi, and S. Josikaea; after the middle of June S. amurensis and S. pekinensis come into bloom, followed by S. japonica as the last, blooming in the North in the beginning of July. S. amurensis and S. pekinensis sometimes bloom sparingly a second time in fall. The foliage is bright green and handsome, but drops comparatively early in fall, especially in S. japonica, without assuming any fall coloring as a rule. In S. oblata the foliage turns to a deep vinous red and remains until November. In S. pekinensis it is retained until late in fall and finally assumes a purplish hue or turns pale yellow.
The foliage is not much attacked by insects, but a fungus, Microsphaera alni, late in summer often covers the whole foliage of S. vulgaris and also of S. chinensis and S. persica with a white mealy coat, while S. oblata is but rarely troubled with this fungus and the other species never. Much damage is sometimes done by a borer, Trochilium denudatum, which lives in the stems and branches of S. vulgaris, but is rarely found in any other species.
After blooming, the inflorescence should be removed if possible and the pruning be done as far as necessary. Pruning in winter or spring would destroy a large part of the flower-buds for the coming season. Lilacs grow in almost any kind of soil, but a rich and moderately moist one is the most suitable. They are easily transplanted at any time from fall to spring. S. vulgaris and its numerous varieties are the most popular of the lilacs on account of their early and profuse blooming, their sweet fragrance, and the variety of colors ranging from dark purple to lilac, pink, and white. The double-flowered varieties keep the blooms longer, but the panicles are less graceful and they usually do not bloom so profusely as the single ones; they also remain mostly dwarfer and have a more compact habit. The faded flowers do not fall off, but remain on the inflorescence; this gives the plant a very unsightly appearance if the faded panicles are not removed. W. J. Stewart suggests a word of warning against lilacs not on their own roots, because of the attacks of borers and the bad habit of suckering in some cases.
Some of the best single-flowered varieties are the following:
Single-flowered Lilacs.—While: Alba grandiflora; Alba pyramidalis; Frau Bertha Dammann, A.F. 12: 1078; Madame Moser; Marie Legraye, one of the very best, B.H. 29:135; Princess Marie; Princess Alexandra is a favorite variety of this class in America.—Blue, lilac, or pink: Ambroise Verschaffelt, pale pink; Dr. Lindley, pinkish lilac, F.S. 14:1481; Geant des batailles, bluish lilac; Geheimrath Heyder, light lilac; Gigantea, bluish red; Gloire des Moulins, pale pink, G.M. 44:499; Goliath, purplish lilac; Lovaniana, light pink; Macrostachya, light pink; Sibirica, purplish lilac; Trianoniana, bluish lilac.—Red: Aline Mocqueris, dark red; Charles X (Caroli), dark lilac-red, A.F. 12:1076. F. 1873, p. 76; Marlyensis, sometimes called Rubra de Marley, lilac-red; Rubra insignis, purplish red.—Dark purple: Philemon; Ludwig Spaeth (Andenken an Ludwig Spaeth, Louis Spaeth), very large panicles, the best of the dark varieties; Negro, deep violet-purple; Congo, deep wine red.
Double-flowered Lilacs.—White: Madame Abel Chatenay, compact panicles; Madame Casimir-Perier, large graceful panicles, one of the best; Madame Lemoine, large fls. in dense panicles; Obelisque; Virginite, white and pink.—Blue, lilac, or pink: Alphonse Lavalle, bluish lilac, A.F. 12:1077; Belle de Nancy, fls. pink with white center; Charles Baltet, lilac-pink; Condorcet, blue, A.F. 12: 1074; Doyen Keteleer, lilac-blue; Jean Bart, pinkish violet; Lamarck, pale lilac, large, rather loose panicles; Lemoinei, lilac-pink, B. H. 28:174; Leon Simon, changing from pinkish to bluish lilac. Gt. 43:1407; Maxime Cornu, pinkish lilac; Michel Buchner, pale lilac, large and very double fls.; President Carnot, pale blue.—Purple: Charles Joly, dark purplish red, one of the darkest; Comte Horace de Choiseul, lilac-purple; La Tour d'Auvergne, violet-purple.
The lilacs have been favorite forcing plants in France for more than a century and are nowadays among, the most important cut-flowers during the winter season in France as well as in Germany and England. They are on the market from the end of September until they bloom outdoors. Charles X is considered one of the very best for forcing. Marlyensis, Marie Legraye, Alba virginalis, Ludwig Spaeth, and other varieties are also good for forcing. Of the double-flowered varieties the following have proved adapted for forcing: Madame Casimir-Perier, Madame Lemoine, Charles Baltet, Jean Bart, Leon Simon, S. chinensis duplex, and others. Either grafted plants or plants on their own roots are used. Both force equally well, but grafted lilacs can be grown into plants well set with flower-buds and suited For forcing in two or three years, while plants grown from cuttings require four to six years. Marlyensis is always used on its own roots and propagated either by seeds, cuttings, or division. Special attention must be given to pruning in order to have well-branched plants of good compact habit (see Fig. 1555, Vol. III, p. 1265). The lilac has nothing like the commercial importance for forcing in America that it has in Europe, but the appreciation of it for winter bloom is on the increase in this country.
Lilacs are generally forced in pots, being potted usually in July or in the fore part of August, that they may fill the pots with new roots before winter. Some growers pot the plants in spring or in the preceding fall. This practice is of especial advantage if the plants are intended for very early forcing. These early potted plants are then plunged into the ground outdoors, mulched, well watered and regularly manured; after June, when the young growth is almost finished, only enough water is given to prevent wilting. When the flower-buds have been formed, more water is given until they have reached their full size. It is essential to keep the plants rather dry in fall, so that the wood may ripen thoroughly and early. When the leaves have fallen off, the plants are stored away in convenient places, where they are sheltered from severe frost. Sometimes the lilac, especially S. marlyensis, is forced from balls of earth which are not potted, but this does not always give satisfactory results.
About three to four weeks is required to force the plants into bloom with the temperature recommended below. The first days after bringing the plants into the forcing-room, a temperature of 55° to 60° may be given, gradually rising to 78° to 88° and maintained as equally as possible until the panicles are fully developed and the first flowers begin to expand; then the temperature is lowered to 60° to 66°, and when the panicles are about half open the plants are transferred to a cool greenhouse. Hardening-off is essential to ensure good keeping qualities of the flowers. The red-flowered varieties are often forced in darkened rooms in order to have the flowers blanched or only slightly colored. The shade of color depends entirely on the time when full light is given and also on the temperature. Show plants in pots should be grown in full light to have the foliage well developed. When the temperature is higher than 76°, frequent syringing is necessary. It is, of course, possible to force lilacs in a lower temperature, and this will even be advisable if the longer time required does not count. Full advice for commercial lilac-forcing is given by Fr. Harms in "Flieder und Asparagus," a book devoted almost exclusively to lilac-forcing.
Interesting experiments recently conducted have shown that the lilac is more readily forced when the plants are subjected to the influence of ether during forty-eight hours shortly before forcing. An account of these experiments by W. Johannsen is entitled "Das Aetherverfahren beim Fruhtreiben mit besonderer Beruckrichtigung des Flieders." That the ether has a particular effect on the metamorphosis and regeneration of the albuminoids in the plant has been stated recently by other botanists also.
Lilacs may be propagated by seed, which is sown in spring. This method is usually practised only with the more common typical species. The many varieties and rarer kinds are usually propagated by greenwood cuttings under glass in June (or in early spring from forced plants), by hardwood cuttings, by grafting, and also by suckers and division, especially in the case of S. chinensis, S. persica, and S. vulgaris. As a stock, S. vulgaris is mostly used and sometimes ligustrum. S. japonica will probably prove to be a good stock. S. villosa, though readily growing from seed and of vigorous habit, is not to be recommended. Budding in July and August is the most extensively practised method. Grafting is done either in April or May in the open or in February or March in the greenhouse on potted stock. Almost any kind of grafting may be employed as the lilac unites readily. Crown-grafting is to be preferred in order to avoid the troublesome suckers. Plants intended for forcing but deficient in flower-buds are sometimes grafted in October or early in November with branches well set with flower-buds and forced in January or later.
Forcing lilacs.—Most of the lilacs used by American commercial florists for forcing are imported. Care should always be taken to procure pot-grown plants, that is, plants that have been grown in pots the previous summer. The florist who wishes to grow his own plants should lift them in the field in April or before the growth starts and pot them without losing much root. Plunge them out-of-doors during summer and give them plenty of water. This treatment will insure a good growth and the check the plants receive from lifting will induce them to form new flower-buds. These plants will force with the greatest certainty. It is well to allow five weeks for the earliest forcing. A strong heat is necessary, beginning at 60° for the first few days and increasing to 75° to 80°, with a daily watering and syringing several times. After the flowers begin to open, the syringing can be discontinued and when fully expedient the plants are better removed to a coolhouse, where they will harden off and be much more serviceable when cut. As the season advances, say March and April, less heat is needed. They will then force in any ordinary house where the night temperature is about 60°F. The Persian lilac, on account of its abundance of bloom and delicate truss, is very desirable, but this must be forced almost in the dark to produce white flowers. Marie Legraye is for all purposes the most useful lilac which has been used for forcing.
S. albo-rosea, N. E. Br., .S. tomentella.—S. Koehneana, Schneid. (S. velutina, Hort., not Komarov). Allied to S. pubescens. Young branchlets puberulous: lvs. oval to oblong-lanceolate, pubescent on both sides, 2-3 in. long: infl. 3-4 in. long, pubescent: fls. pale lilac. China.—S. Komarovii, Schneid. Allied to S. villosa. Lvs. oblong-ovate, pubescent beneath, 4-6 in. long: infl. narrowly pyramidal, to 6 in. long, pubescent: corolla lilac; anthers partly exserted. W. China. Var. Sargentiana, Schneid. Branchlets slightly pubescent: infl. usually somewhat larger: corolla purple; anthers usually scarcely exserted. W. China.—S. Meyeri, Schneid. Allied to S. pubescens. Small shrub: lvs. elliptic-ovate, sparingly pubescent beneath: infl. rather dense: fls. lilac with very slender tube over 1/2 in. long. N. China. Blooms when scarcely a foot high.—S. pinnatifolia, Hemsl. Allied to S. persica. Lvs. pinnate, 2 - 3 1/8 in. long with 9-11 sessile and decurrent lfts.: infl. slender, about 2 in. long; fls. whitish pink, the tube 1/2 in. long. W. China. G.C. III. 55:269. —S. Rehderiana, Schneid. Allied to S. villosa. Branchlets tomentose: lvs. elliptic, pubescent on both sides, 3-4 in. long: infl. broadly pyramidal, to 7 in. long, villous: fls. white. W. China.—S. Sargentiana, Schneid.-S. Komarovii var. Sargentiana.—S. sempervirens, Franch. Shrub, to 4 ft., glabrous: lvs. persistent, coriaceous, broadly oval, obtuse or acutish, 1 – 1 3/4 in. long: fls. white, 1/4 in. long, in dense panicles 2-3 in. long: fr. fleshy, dehiscent. S. W. China. It looks more like a privet than like a lilac; not hardy N. —S. Sweginzowii, Koehne & Lingelsh. Allied to S. villosa. Lvs. ovate, usually rounded at the base, pubescent beneath only near the veins, 2-4 in. long: infl. to 10 in. long, with purple rachis: fls. yellowish white suffused with pink, fragrant, the tube about 1/3 in. long. E.Asia. G.C. III. 57:345. M.D. 1910, p. 112.—S. tomentella, Bur. & Franch. (S. albo-rosea, N. E. Br.). Allied to S. villosa. Branchlets glabrous or short-pubescent: lvs. elliptic to oblong-lanceolate, more or less pubescent beneath, 1 - 3 1/2 in. long: infl. dense, to 7 in. long, puberulous; fls. lilac-pink; tube over 1/3 in. long. W. China. M.D. 1910, p. 112.— S. velutina, Hort., not Komarov-S. Koehneana. The true S. velutina, Komarov, is apparently not in cult.; it differs chiefly in its larger lvs. and the glandular petioles and infl. — S. Wilsonii, Schneid. Allied to S. villosa. Lvs. elliptic-ovate, to elliptic-lanceolate, pubescent beneath near the veins, 2 1/2-5 in. long: infl. broad, to 6 in. long, glabrous or nearly so; fls. white or lilac, tube about 1/3 in. long. W. China — S. Wolfii, Schneid. Allied to S. villosa. Lvs. elliptic-oblong, nearly glabrous: infl. to 12 in. long: fls. lilac, fragrant, 3/4 in. long. N. China. Remarkable for its very large panicles. —S. yunnanensis, Franch. Allied to S. villosa. Shrub: lvs. elliptic-oblong to oblong-lanceolate, glaucescent beneath, glabrous, 1 1/2 – 3 1/2 in. long: infl. slender, 3-6 in. long, puberulous: fls. pinkish, with upright-spreading lobes. S. W. China. CH
Pests and diseases
- ↑ Flora Europaea: Syringa
- ↑ 2.0 2.1 Flora of China: Syringa
- ↑ 3.0 3.1 Flora of Pakistan: Syringa
- ↑ 4.0 4.1 Germplasm Resources Information Network: Syringa
- ↑ Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.