|Tulipa subsp. var.||Tulip|
A tulip is a bulbous plant in the genus Tulipa, comprising 109 species with showy flowers, in the family Liliaceae. The species native range includes southern Europe, North Africa, and Asia from Anatolia and Iran in the west to northeast of China. The centre of diversity of the genus is in the Pamir and Hindu Kush mountains and the steppes of Kazakhstan. A number of species and many hybrid cultivars are grown in gardens, used as pot plants or as fresh cut flowers. Most cultivars of tulip are derived from Tulipa gesneriana.
The species are perennials from bulbs, the tunicate bulbs often produced on the ends of stolons and covered with hairless to variously hairy papery coverings. The species include short low-growing plants to tall upright plants, growing from 10 to 70 centimeters (4–27 in) tall. They can even grow in the cold and snowy winter. Plants typically have 2 to 6 leaves, with some species having up to 12 leaves. The cauline foliage is strap-shaped, waxy-coated, usually light to medium green and alternately arranged. The blades are somewhat fleshy and linear to oblong in shape. The large flowers are produced on scapes or subscapose stems normally lacking bracts. The stems have no leaves to a few leaves, with large species having some leaves and smaller species have none. Typically species have one flower per stem but a few species have up to four flowers. The colourful and attractive cup shaped flowers typically have three petals and three sepals, which are most often termed tepals because they are nearly identical. The six petaloid tepals are often marked near the bases with darker markings. The flowers have six basifixed, distinct stamens with filaments shorter than the tepals and the stigmas are districtly 3-lobed. The ovaries are superior with three chambers. The 3 angled fruits are leathery textured capsules, ellipsoid to subglobose in shape, containing numerous flat disc-shaped seeds in two rows per locule. The flat, light to dark brown seeds are arranged in two rows per chamber and have very thin seed coats and endosperm that does not normally fill the entire seed coat.
|Standard Cyclopedia of Horticulture|
Tulipa (originally from Persian toliban, turban; which the inverted flower resembles). Liliaceae. Tulip. Popular spring-flowering hardy bulbs, and much used for forcing; of easy culture.
Low plants, the fls. mostly single (sometimes 2-5) on a scape or scape-like peduncle that arises directly from the bulb and is 30 in. or less high: bulb tunicated, the outer tunic often hairy or woolly on the inner face: lvs. linear or broad: fls. erect, rarely nodding, showy; perianth deciduous, campanulate or slightly funnel-shaped; segms. distinct, often spotted or blotched at base, without pitted nectaries; stamens 6, hypogynous, shorter than perianth-segms.; filaments longer or shorter than anthers, attenuate or filiform; anthers dehiscing laterally; ovary sometimes narrowed at collar, rarely into a distinct style; stigmas adnate: seeds numerous, flat. Differs from Fritillaria in the absence of nectariferous pits and usually erect (never pendulous) fls., and from Erythronium in its erect broader perianth-segms., erect fls., and usually 1-fld. sts. Native of Siberia, Turkey, Asia Minor, China, Japan, and Medit. countries of Eu.; the species are particularly abundant in Cent. Asia, in the Bokhara region. The genus includes probably 100 species as usually defined but perhaps reducible to much fewer; the number in cult., outside the collections of specialists and botanic gardens, is very few. For literature, see J. G. Baker, Journal Linnean Society xiv. (1875), 275-96; also in Gardeners' Chronicle, for 1883 (vols. 19 and 20): Levier, "Les Tulipes de l'Europe," 1885; Solms-Laubach on the history of the garden tulips (see his "Weizen und Tulpe, und deren Geschichte," Leipzig, 1899); Burbridge, The Garden, Sept. 22, 1900.
Tulips are flowers of rich and brilliant colors, and of good "substance." The tulip is the most showy of spring flowers, and the habit and shape of the plant are so formal and definite that it is adapted to the vicinity of buildings, walks, and to parterres. They are also charming subjects for "spotting in" singly and in little clumps among shrubbery and along well-planted borders.
The range of season is great, from the early Duc Van Thols to the Cottage and late Darwins, covering nearly two months. By a judicious selection of seasons and colors, the amateur may have a most satisfactory successional display, one kind blending into the other. The catalogues of plantsmen and seedsmen usually contain reliable lists of varieties for the different seasons. They are dwarf, from about a foot high in the early races, to very tall, as much as 2 and 3 feet in some of the Darwins and other month-later races. There are double tulips of good form and many colors; also the Parrot tulips with curiously enlarged and cut or frayed petals and odd color-markings. The graceful chalice-lines of the single tulips are lost in the double and semi-double forms; the doubles, however, make striking mass displays; they are usually somewhat later-blooming than the singles of the same class.
The form of the chalice or perianth-cup, the substance of the flower, the shape of the segments, and the color, are marked features in the tulips of the different classes and seasons. The usually cultivated tulips have very broad flower-segments, obtuse or abruptly narrowed and short-pointed, as in Fig. 3862. In the wild, however, are many forms with long-narrowed segments, as shown in Fig. 3863 (adapted from Gardeners' Chronicle), and these may be seen sometimes in the gardens of amateurs; they are very interesting and often showy. It appears that in earlier times the sharp-pointed flower-parts were desired. Other tulip forms are represented in Figs. 3864 and 3865, as well as in the succeeding pictures accompanying this article.
The colors of tulips cover a wide range except that there are no real blues. There are clear whites, yellows and orange, crimsons and reds, violets and purples, and many vari-colored types. The tulips known as "breeders" are self-colored kinds; that is, the flowers are of solid colors, usually in dull and neutral shades of red and yellow with tints of bronze, buff, and brown. The reason for the name is this: When tulips are grown from seeds, the flowers at first are usually self-colored; the same bulbs when grown for a few years tend "to break" into mixed colors, particularly into feathered markings: the self-colored state is a breeding-stage for other kinds. When the bulbs are multiplied asexually (as explained farther on), they reproduce the stage in which they then are; if propagated in the "breeder" stage, they give self-colored flowers; if in the "broken" stage, they give parti-colored flowers. These stages are longer or shorter in different lots of seedlings, and are not definite epochs. The "broken" tulips are of many kinds. Those with white ground or under-color and lilac or purple markings are "bybloemen" or "bybloems," and those with yellow ground-color and red to brown over-color are "bizarres." The terms "bybloem" and "bizarre" are also sometimes applied to selfs, or breeders, when the colors are prevailingly lilac or purple in the one case or prevailingly yellow in the other. Selected strains of breeder tulips, with very large bloom, long stems, and "art colors" are now popular. The so-called "rectified" tulips are broken breeders with solid colors in stripes, flames, plumes, and patches; they are bybloemen and bizarres. It is said that the "breaking" is facilitated by certain soils.
There are many classes of tulips. We might distinguish three roughly: (1) The early single tulips of the Duc Van Thol kind, of small stature, excellent for first bloom and for early bedding, being out of the way for other bedding plants; they lack the size of bloom and the "substance" of later kinds. There are also later-flowering single tulips of the early class. (2) Later-flowering or Cottage tulips, comprising the main-season kinds that have been preserved by cottagers in the old countries since the collapse of the tulipomania of Holland. (3) The Darwins are stately plants, mostly selfs or "breeders," closing the tulip season, with very rich and deep colors in crimsons, reds and purples; there are some whites but no yellows. This Darwin race is relatively recent, having been given its present name (in compliment to Charles Darwin) little more than twenty-five years ago. Broken rectified Darwins in several color combinations are known as Rembrandt tulips.
There are many other classes or subclasses, and races of intermediate season, that need not be mentioned here.
Vari-colored garden tulips are classified by F. D. Horner (England) into six main sections or classes, and the self-colored or "breeder" strains into three classes, as follows: "(1) Flamed Bizarres. These have a yellow ground flamed with red, very dark, almost black, and chestnut-brown. (2) Feathered Bizarres. These have similar colors, but the yellow grounds are marked or penciled on the margin, whereas the flamed flowers have a heavy 'beam' of color in the center of the petals. (3) Flamed Bybloemens. These have a white ground marked with lilac, purple, and very deep black-purple color. (4) Feathered Bybloems. Similar in color, but with feathered instead of flamed petals. (5) Flamed Roses. These are flamed with rose and scarlet colors on the pure white ground. (6) Feathered Roses. These have a white ground, and are flamed with rose and scarlet colors. There are three more classes of what are termed 'breeders.' Bizarres. Yellow selfs. Bybloemens. Lilac and light to deepest purple selfs. Roses. Rose and scarlet selfs. They are termed 'breeders' because in the course of a few years these self-colored flowers become flamed or feathered, and pass out of the breeder state."
The common garden tulips, in their many forms, are probably all developments of the Gesneriana group, comprising T. Gesneriana, T. suaveolens, and the like. Many of the forms sometimes catalogued as "botanical tulips" are also very ornamental and are always interesting in a collection. A number of species may be had in the trade. They should be better known.
Tulip history (Stubenrauch).
The tulip has an unusual and interesting history, on which we may pause briefly.
The origin of the garden tulip seems to be lost beyond recovery. It is often said that it is derived from Tulipa Gesneriana, but this does not explain. It merely means that in 1753 Linnaeus grouped all the garden tulips he knew under the name of Tulipa Gesneriana. But the tulips of that day had been cultivated for two centuries by Europeans, and previously for an indefinite period by the Turks, from whom, of course, we have no exact records. (Fig. 3866.) One might study wild tulips in their native places and compare them with descriptions without being certain of the original form which the Turks brought from the wild, simply because of the lack of records at the beginning. It is necessary to have some scientific name for the garden tulips. The most one dare say is that the garden tulips are chiefly referable to T. Gesneriana and T. suaveolens, with the distinct understanding that these names do not represent an original wild stock. Tulipa suaveolens requires explanation. This name, which dates from 1797, stands for a kind of tulip discovered wild in southern Europe long before that date. There is no proof that it was native; the probability is that it had escaped from gardens and run wild. In 1799, it was distinguished from the other tulips then known by the fragrance of the flowers, the earliness of bloom, slightly greater size and pubescent scape. From the early records it appears that there were fragrant early-blooming flowers among the first tulips received from Turkey. This is one of the main reasons for thinking that T. suaveolens is not native to southern Europe. At all events, it is clear that T. suaveolens has played an important part in the evolution of the garden tulip, the Duc van Thol class being credited to this source. The distinctions between T. suaveolens and T. Gesneriana given in the sequel are those of Baker, but they do not hold at the present day. It is impossible to refer any given variety with satisfaction to either type. Some writers have said that the leaves of T. suaveolens are shorter and broader than those of T. Gesneriana. This character also fails. All grades of pubescence are present. Some pubescent plants have long leaves and odorless flowers. Others have short glabrous leaves and fragrant flowers.
For practical purposes it may be said that most of the common garden tulips, at least the late-flowering ones, are T. Gesneriana, while many of the early-flowering kinds, e.g., the Duc van Thol class, are supposed to be derived from T. suaveolens. It is impossible to press much nearer the truth, as the prototypes of the old garden favorites cannot be known completely and precisely.
The first tulip seeds planted by Europeans were sent or brought to Vienna in 1554 by Busbequius, the Austrian ambassador before the Sultan of Turkey. Busbequius reported that he first saw the flowers in a garden near Constantinople, and that he had to pay dearly for them. After the introduction of seed to Vienna the tulip became rapidly disseminated over Europe, both by home-grown seed and by new importations from Turkey. In 1559 Gesner first saw the flower at Augsburg, and it is mainly on his descriptions and pictures that the species T. Gesneriana was founded. One of the earliest enthusiasts was the herbalist Clusius, who propagated tulips on a rather large scale. A picture from him is shown in Fig. 3866. He did not introduce the tulip into Holland, but the appearance of his specimens in 1591 did much to stimulate the interest in the flower in that country. The best of Clusius' plants were taken from him, as the admirers of the tulip were unwilling to pay the high prices he demanded. After this, the propagation of the tulip proceeded rapidly in Holland and the flower soon became a great favorite. The production of new varieties became a craze throughout the Netherlands, culminating in the celebrated "tulipomania" which began in 1634. The excitement continued for four years, the price of bulbs often being above that of the precious metals. Thirteen thousand florins were paid for a single bulb of Semper Augustus; but the dealings were often in the nature of pure speculation, no bulbs changing hands. Governmental interference was necessary in order to end the ruinous speculation. After the craze subsided, the production of varieties continued upon a normal basis, and has persisted throughout the centuries in Holland, making that country the center of the bulb-growing industry of the world down to the present day.
The introduction of the tulip into England is credited to Clusius, about the year 1577. Tulips reigned supreme in English gardens until the beginning of the eighteenth century, when they were neglected by the rich for the many new plants from America. For a time the tulip was considered more or less of a poor man's flower, although it has at no time been without many staunch admirers among the upper classes.
With the Turks the narrow acuminate flower-segments were in favor, while western taste preferred the rounded forms (Fig. 3868). The Turks seem to have been satisfied with a preponderance of the reds and yellows, for in the first sowings of Turkish seeds the larger part of the resulting blooms were of those colors. It thus came about that flowers so colored were considered common and undesirable in the European gardens and all effort was directed to the production of the rarer white-grounded varieties with finely and distinctly marked stripes, those with a sharp bright red being the favorites. Indisputable evidence of this is seen in the old Holland "still-life" paintings of that time, where one finds none but the rarer forms represented (Solms-Laubach). All the early tulips of direct Turkish origin had acute more or less narrow and reflexed segments. Indeed, among all the old engravings, including those of Pena and Lobel (1570), Clusius (1576), Dodoens (1578), and Besler (1613), no round-petaled forms are found. Besler's work, "Hortus Eystettensis," contains magnificent copper plates, the first in any book on plants. In some copies the plates are beautifully colored by hand. The fifty-three figures of tulips in this great work show how widely diversified was this flower even at that early date. In this and in Parkinson's "Paradisus Terrestris" (1629), many are figured with inner segments rounded and outer acute, but none vice versa (so far as can be seen), although that form is mentioned in the descriptions. The broad, rounded, erect-petaled forms were developed later, apparently first by the Dutch growers before the tulipomania and contemporaneously with it, and produced wholly by selection. This ideal has prevailed down to the present time, for the narrow-petaled varieties are practically unknown among our common garden forms, so much so that the extreme typical one has been referred to a separate species (T. acuminata, Fig. 3872). In the Dutch fields they are now known as "thieves," and are destroyed as soon as they make their appearance. The quest for unusual colors appears to have been one feature of the tulip furore. Dumas' "Black Tulip" is interesting in this connection.
Parrot tulips were known toward the end of the seventeenth century. They were often considered to be monstrosities and were pictured as such. According to Solms-Laubach, no traces of them are to be found in the old Dutch books. They were evidently developed by the French, who did not disdain the yellow and red forms, to which these belong, to such an extent as did the Hollanders. At one time they were made a separate species, T. turcica, and were later said by one author to be hybrids, between T. acuminata and T. sylvestris (E. S. Rand, Jr., 1873), by another between T. Gesneriana and T. suaveolens (Mrs. Loudon, 1841). That the Parrot tulips are hybrids is perhaps true, but to state with certainty the parents seems impossible, for as early as 1613, among the figures in Hortus Eystettensis, there is one which shows laciniation of the petals to a marked degree, sufficiently so, in fact, to be the original form from which this strain might have been developed. Many of the garden varieties of today exhibit more or less laciniation, so that it is probable that "Parrot" strains might be developed from them by simple selection.
Double tulips seem to have made their appearance at an early date. In "Hortus Eystettensis" (1613), there are four forms figured, one of which, at least, seems to have been almost wholly made up of bracts, as it is shown entirely green and is described as being "wholly herbaceous and green." The other three there figured are: one red, one yellow, and the other white with maroon borders. Solms-Laubach places the advent of double tulips at a much later date, 1665, and gives as the first authentic record the account of "Tulipa lutea centifolia, le monstre jaune double." Flowers with as many as 200 petals are mentioned. A double form of "T. serotina" was known in 1701, and at the beginning of the nineteenth century a double form of T. sylvestris was described.
Cultivation of the tulip.
The tulip is one of the easiest plants to grow, but, like other plants, it profits by extra care. In any ordinary soil it gives excellent satisfaction, if good bulbs are secured in the first place.
For outdoor cultivation for spring bloom the bulbs should be set in September to December in the latitude of New York. They should be planted before hard freezing weather comes. The soil should be a sandy loam, well worked to a depth of at least 12 inches for best results, and enriched with leaf-mold and well-rotted cow-manure. Fresh manure of any kind should never be used near bulbs of any sort. On heavier soils tulips can be successfully raised if extra care is given to insure perfect drainage. Drainage is important under all conditions. The bulbs will never prove satisfactory in low wet situations, and if there is danger from standing water it is best to raise the beds several inches above the surrounding ground. The production of large perfect flowers depends on a large supply of fibrous roots. Size of bulbs is not so important: a large bulb cannot offset a deficiency of roots.
Plant the bulbs 4 to 6 inches deep (to the bottom of the bulbs) and 4 to 9 inches apart, depending on the class or size of the plants, the closer distances being for the early single kinds and the wider distances for the later and larger kinds. Care should be exercised to place all the bulbs at the same depth, as otherwise they will not all bloom at the same time. When the ground begins to freeze, cover the beds with leaves, dry forest litter, or other light material. After danger of heavy frosts is past in spring the beds should be uncovered, and if the work of preparation and planting has been well done the tulips will require little or no further care. In England many of the beds of choice and delicate varieties of tulips are protected when in flower from heavy rains and hot sun by means of light cloth screens, and are thus kept in good condition for some time.
Tulips may remain in the ground several years if the tops are not cut off and if the maturing leaves are not smothered by other plants. In practice, however, the best results are usually not secured in this country after the bulbs have been in the ground two or three years. The Darwin class seems to lack in constitution, and the plants should be renewed every two years or so.
In old-fashioned gardens, tulips often remain year after year; but when the beds are needed for other flowers in succession, the bulbs are lifted as soon as the flowers are past and reset elsewhere until the plants mature and the tops die down naturally. Then the bulbs are taken up, sorted and dried, and stored in a cool dark place until planting-time; or they may be planted at once in the permanent quarters if the area is ready to receive them. Even in borders and among shrubbery, it is well to take up the bulbs every two or three years and sort out the small ones, replanting the remainder; or, if they are weak, to discard all of them for new ones. For the best bedding work, it is advisable to use strong freshly imported stock each year.
To make design-beds, choose bulbs of very uniform size. Dig out the bed, removing all the earth a little deeper than the bulbs are to be planted, then make a thin layer of soft earth on which the bulbs may rest; this surface should be stroked level and be at a uniform depth. Then place the bulbs in the design and fill in around them carefully by hand; then place the earth back in the bed.
For pot culture (winter and spring bloom), a mixture of fine garden loam, two parts to one of well-rotted manure (cow-manure composted for two years is best), mixed with enough clean sand to make the mass easily friable, is most suitable. If no loam is obtainable and a heavier garden soil must be used, one part of the latter will be sufficient, in which case the addition of an equal proportion of leaf-mold will be advantageous. From three to five bulbs, according to size, to a 5-inch pot are effective. Deep pans are often used with good effect; a 6-inch pan may hold five or six early singles, and an 8-inch pan as many as ten (Figs. 3867, 3868). Fill the pots lightly and press the bulbs into the soil, thus bringing the base in close contact with the soil-particles. Cover the bulbs to the tip and press the soil firmly all around. Water once freely and cover the pots entirely with soil, leaves, or litter, so that they will be out of reach of frost, or place them in a dark cold (not freezing) cellar or room until the bulbs have become well rooted, which under ordinary conditions will require five or six weeks. When the pots have become well filled with roots—the more the better—they are ready to be brought into the house. For the first few days at least the temperature should be moderate and even, and the atmosphere not too dry. Water freely but not to excess. Some of the varieties—especially the white thin-petaled ones—are said to resent over-watering very quickly. If raised in living-rooms greater care is necessary, as the atmosphere of such a room is drier than that of a greenhouse. On cold nights the plants should be removed from exposed places where they are liable to freeze, and when the flowers appear they should not be allowed to stand in the direct rays of the sun shining through a window. Many of the handsomest flowers are thus easily burned and wilted. Practically all of the early single varieties are adapted to pot culture, especially the Duc van Thols when well rooted; otherwise they are extremely unsatisfactory. For a succession, pot every week or ten days from September to December or pot early and bring into the house at fortnightly intervals. Avoid caking the soil beneath bulbs. The single early tulips are best for forcing, although some of the Darwins give good results.
Many of the early single varieties are adapted to water-culture. For this purpose use ordinary "hyacinth glasses and select only well-formed solid perfect bulbs of fair size. Put a little charcoal in the water to keep it pure. The bulbs must be placed so that the base is just in contact with the water—not immersed in it. Place them in a dark closet for ten days or a fortnight until the bulbs have become well rooted, then give them plenty of light and air.
Propagation is effected in various ways. Tulips may be increased by the side offsets, but these are not so constant as new bulbs produced within the outer tunics by means of cutting the old bulbs. Fig. 3869 shows a section of a bulb with new inner bulb and outer offset in place. The new bulb is completely inclosed in a sac which afterward becomes the outer dry membranous tunic. The pubescence, if any, may be found on the inside of this sac, even in the earliest stages of growth. The new bulb is attached to the base of the flower-stem, immediately above the root-crown from which the former proceeds directly upward. Each new bulb-tunic (including the outer sac) is provided with a growing tip, which often extends above ground into a leaf, each one coming up within the other. Fig. 3869 shows the separated leafy bulb-scales, and indicates the homology of tunics and leaves. Sports among the offsets are at present mainly depended on for the production of new varieties. These have been found susceptible to the "breaking" process, though perhaps slower to respond than the seedlings. Seed production is now practised only in exceptional cases. The production of hybridized varieties by crossing the old forms with some of the newly introduced species is likely to come into favor.
Tulips are "Holland bulbs;" that is to say, the bulbs are grown mostly in Holland and are extensively shipped to this country. Considerable interest has been aroused in the growing of commercial bulbs in this country, particularly in the Puget Sound region. The tulip can be grown to perfection in the Pacific Northwest, but the cost of production, on account of the high wage-rate, may be a controlling problem. As the situation looks now, the American can produce fully as good a bulb, and one that will mature earlier than the Holland-grown; but whether the product can be sold in the eastern market in competition with the Dutch is a question yet to be determined. It is probable that the bulbs can be grown as far south as San Francisco. South of San Francisco, the single early tulips bloom very close to the ground; on the other hand, the Darwins seem to do very well in the Santa Cruz and Ventura regions. At the government bulb-farm at Bellingham, Washington, good tulip bulbs with normal increase have been produced under adverse conditions.
T. flava, Hort., is "often confused with vitellina in gardens, though perfectly distinct. Flava is yellow, very robust, tall, and at least a fortnight later in blooming. Vitellina is almost white when old." Imperfectly known.—T. Fosteriana, Hort. Fls. very large, rich intense glowing crimson with a darker blotch at the base of the segms.: lvs. very broad, many-nerved: of robust habit and easily grown. Bokhara. G.C. III. 39:323.—T. galatica, Freyn. Tunics silvery hirsute within: st. glabrous: lvs. linear-lanceolate, acuminate: fls. yellow; outer segms. elliptic to oblong-elliptic; inner segms. spatulate, rounded. Asia Minor.—T. lanata, Regel. Dwarf: fls. large, goblet-shaped, rich vermilion, with a large black spot at the base of each of the segms. Bokhara.—T. Leichtlinii, Regel. Bulb-tunics glabrous inside: height 9-18 in.: st. glabrous: lower lvs. lanceolate-linear: fl. erect; perianth between campanulate and funnelform; outer segms. narrow and acute, the outer bright purple with broad white margin, the inner much shorter and obtuse at apex and yellowish white. Kashmir. Gn. 40:174. CH
Tulips are indigenous to mountainous areas with temperate climates and need a period of cool dormancy. They do best in climates with long cool springs and early summers, but are often grown as spring blooming annual plantings in warmer areas of the world. The bulbs are typically planted in late summer and fall, normally from 10 to 20 cm (4 to 8 in.) deep, depending on the type planted, in well-drained soils. In parts of the world that do not have long cool springs and early summers, the bulbs are often planted up to 12 inches deep; this provides some protection from the heat of summer and tends to force the plants to regenerate one large bulb each year instead of many smaller non-blooming ones. This can extend the usefulness of the plants in warmer areas a few years but not stave off the degradation in bulb size and eventual death of the plants.
Tulips can be propagated through offsets, seeds or micropropagation. Offsets and Tissue Culture methods are means of asexual propagation, they are used to produce genetic clones of the parent plant, which maintains cultivar integrity. Seed raised plants show greater variation, and seeds are most often used to propagate species and subspecies or are used for the creation of new hybrids. Many tulip species can cross pollinate with each other; when wild tulip populations overlap with other species or subspecies, they often hybridize and have populations of mixed plants. Most tulip cultivars are complex hybrids and sterile; those plants that do produce seeds most often have offspring dissimilar to the parents.
Tulip growers using offsets to produce salable plants need a year or more of growth before plants are large enough to flower; tulips grown from seeds often need five to eight years of growth before plants are flowering size. Commercial growers harvest the bulbs in late summer and grade them into sizes; bulbs large enough to flower are sorted and sold, while smaller bulbs are sorted into sizes and replanted. Holland is the main producer of commercially sold plants, producing as many as 3 billion bulbs annually. 
Pests and diseases
Botrytis tulipae is a major fungal disease affecting tulips, causing cell death leading to rotten plants. Other pathogens include Anthracnose, bacterial soft rot, blight caused by Sclerotium rolfsii, bulb nematodes, other rots including blue molds, black molds and mushy rot.
Historically variegated varieties admired during the Dutch tulipomania gained their delicately feathered patterns from an infection with Tulip Breaking potyvirus, the mosaic virus that was carried by the green peach aphids, Myzus persicae. Persicae were common in European gardens of the seventeenth century. While the virus produces fantastically colourful flowers, it also caused weakened plants that died slowly. Today the virus is almost eradicated from tulip growers' fields. Those Tulips affected by mosaic virus are called "Broken tulips"; they will occasionally revert to a plain or solid colouring, but still remain infected with the virus.
- Div. 1: Single early - with cup-shaped single flowers, no larger than 8cm across (3 inches). They bloom early to mid season. Growing 15 to 45cm tall.
- Div. 2: Double early - with fully double flowers, bowl shaped to 8cm across. Plants typically grow from 30-40cm tall.
- Div. 3: Triumph - single, cup shaped flowers up to 6cm wide. Plants grow 35-60cm tall and bloom mid to late season.
- Div. 4: Darwin hybrid - single flowers are ovoid in shape and up to 8cm wide. Plants grow 50-70cm tall and bloom mid to late season. This group should not be confused with older Darwin tulips, which belong in the Single Late Group below.
- Div. 5: Single late - cup or goblet-shaded flowers up to 8cm wide, some plants produce multi-flowering stems. Plants grow 45-75cm tall and bloom late season.
- Div. 6: Lilly-flowered
- Div. 7: Fringed (Crispa)
- Div. 8: Viridiflora
- Div. 9: Rembrandt
- Div. 10: Parrot
- Div. 11: Double late
- Div. 12: Kaufmanniana
- Div. 13: Fosteriana (Emperor)
- Div. 14: Griegii
- Div. 15: Species (Botanical)
- Div. 16: Multiflowering - not an official division, these tulips belong in the first 15 divisions but are often listed separately because they have multiple blooms per bulb.
They may also be classified by their flowering season: 
- Early flowering: Single Early Tulips, Double Early Tulips, Greigii Tulips, Kaufmanniana Tulips, Fosteriana Tulips, Species Tulips
- Mid-season flowering: Darwin Hybrid Tulips, Triumph Tulips, Parrot Tulips
- Late season flowering: Single Late Tulips, Double Late Tulips, Viridiflora Tulips, Lily-flowering Tulips, Fringed Tulips, Rembrandt Tulips
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963
- w:Tulip. Some of the material on this page may be from Wikipedia, under the Creative Commons license.
- Tulip QR Code (Size 50, 100, 200, 500)
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