|Iris subsp. var.||Iris|
|Standard Cyclopedia of Horticulture|
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Iris is a genus of between 200–300 species of flowering plants with showy flowers. It takes its name from the Greek word for a rainbow, referring to the wide variety of flower colors found among the many species. As well as being the scientific name, iris is also very widely used as a common name; for one thing, it refers to all Iris species, though some plants called thus belong to other closely related genera. In North America, a common name for irises is 'flags', while the plants of the subgenus Scorpiris are widely known as 'junos', particularly in horticulture. It is a popular garden flower in the United States.
The genus is widely distributed throughout the north temperate zone. Their habitats are considerably varied, ranging from cold and montane regions to the grassy slopes, meadowlands and riverbanks of Europe, the Middle East and northern Africa, Asia and across North America.
Irises are perennial herbs, growing from creeping rhizomes (rhizomatous irises), or, in drier climates, from bulbs (bulbous irises). They have long, erect flowering stems, which may be simple or branched, solid or hollow, and flattened or have a circular cross-section. The rhizomatous species usually have 3–10 basal, sword-shaped leaves growing in dense clumps. The bulbous species have cylindrical, basal leaves.
The inflorescences are fan-shaped and contain one or more symmetrical six-lobed flowers. These grow on a pedicel or lack a footstalk. The three sepals, which are spreading or droop downwards, are referred to as "falls". They expand from their narrow base, which in some of the rhizomatous irises has a "beard" (a tuft of short upright extensions growing in its midline), into a broader expanded portion ("limb"), often adorned with veining, lines or dots. The three, sometimes reduced, petals stand upright, partly behind the sepal bases. They are called "standards". Some smaller iris species have all six lobes pointing straight outwards, but generally, limb and standards differ markedly in appearance. They are united at their base into a floral tube that lies above the ovary (known as an inferior ovary). The styles divide towards the apex into petaloid branches; this is significant in pollination.
The iris flower is of special interest as an example of the relation between flowering plants and pollinating insects. The shape of the flower and the position of the pollen-receiving and stigmatic surfaces on the outer petals form a landing-stage for a flying insect, which in probing the perianth for nectar, will first come in contact of perianth, then with the stigmatic stamens in one whorled surface which is borne on an ovary formed of three carpels. The shelf-like transverse projection on the inner whorled underside of the stamens is beneath the over-arching style arm below the stigma, so that the insect comes in contact with its pollen-covered surface only after passing the stigma; in backing out of the flower it will come in contact only with the non-receptive lower face of the stigma. Thus, an insect bearing pollen from one flower will, in entering a second, deposit the pollen on the stigma; in backing out of a flower, the pollen which it bears will not be rubbed off on the stigma of the same flower.
Irises are extensively grown as ornamental plants in home and botanical gardens. Presby Memorial Iris Gardens in New Jersey, for example, is a living iris museum with over 10,000 plants, while in Europe the most famous iris garden is arguably the Giardino dell'Iris in Florence (Italy) which every year hosts one of the most famous iris breeders' competitions in the world.
The most commonly found garden iris is the bearded German Iris (I. germanica), a hybridogenic species, and its numerous cultivars. Various wild forms and naturally occurring hybrids of the Sweet Iris (I. pallida) and the Hungarian Iris (I. variegata) form the basis of most all modern hybrid bearded irises. Median forms of bearded iris (intermediate bearded, or IB; miniature tall bearded, or MTB; etc.) are derived from crosses between tall and dwarf varieties.
The bearded irises are easy to cultivate and propagate, and have become very popular in gardens. They grow in any good free garden soil, the smaller and more delicate species needing only the aid of turf ingredients, either peat or loam, to keep it light and open in texture. The earliest to bloom are species like I. junonia and I. reichenbachii, which flower as early as February and March, followed by the dwarf forms of I. pumila which blossom during March, April and May. During the latter month and the following one, most of the larger-growing "tall bearded" irises bloom, such as the German Iris and its variety florentina, Sweet Iris, Hungarian Iris, Lemon-yellow Iris (I. flavescens), Iris sambucina, I. amoena, and their natural and horticultural hybrids such as those described under names like I. neglecta or I. squalens and best united unter I. × lurida.
The section Oncocyclus contains the cushion irises or royal irises, a group of plants noted for their large, strongly marked flowers. Between 30 and 60 species are classified in this section, depending on the authority. Compared with other irises the cushion varieties are scantily furnished with narrow sickle-shaped leaves and the flowers are usually borne singly on the stalks; they are often very dark and in some almost blackish. The cushion irises are somewhat fastidious growers, and to be successful with them they must be planted rather shallow in very gritty well-drained soil. They should not be disturbed in the autumn, and after the leaves have withered the roots should be protected from heavy rains until growth starts again naturally.
The section Regelia, closely allied to the cushion irises, includes several garden hybrids with species in section Oncocyclus, known as Regelio-cyclus irises. They are best planted in September or October in warm sunny positions, the rhizomes being lifted the following July after the leaves have withered.
A truly red bearded iris remains an unattained goal despite frequent hybridizing and selection. There are species and selections, most notably based on the beardless rhizomatous Copper Iris (I. fulva), which have a relatively pure red color. However, getting this color into a modern bearded iris breed has proven very difficult, and thus, the vast majority of irises are in the purple and blue range of the color spectrum, with yellow and whitish breeds also quite frequent.
Other beardless rhizomatous iris types commonly found in garden are the Siberian Iris (I. sibirica) and its hybrids, and the Japanese Iris (I. ensata) and its hybrids. "Japanese iris" is also a catch-all term for the Japanese Iris proper (hanashōbu), the Blood Iris (I. sanguinea, ayame) and the Rabbitear Iris (I. laevigata, kakitsubata). I. unguicularis is a late-winter-flowering species from Algeria, with sky-blue flowers blotched with yellow, produced (in the Northern Hemisphere) from November to March or April. Yet another beardless rhizomatous iris popular in gardening is I. ruthenica, which has much the same requirements and characteristics as the "tall bearded" irises.
Many of the smaller species of bulbous iris, being liable to perish from excess of moisture, should have a well-drained bed of good but porous soil made up for them, in some sunny spot, and in winter should be protected by a covering of half-decayed leaves or fresh cocos-fibre refuse. To this group belong the "reticulate" irises with their characteristic bulbs, including I. danfordiae, I. histrioides, I. reticulata and others, as well as the smmoth-bulbed I. filifolia, which flower as early as February and March
Pests and diseases
In general, modern classifications usually recognise six subgenera, of which five are restricted to the Old World; the sixth (subgenus Limniris) has a Holarctic distribution. The two largest subgenera are further divided into sections.
Bearded rhizomatous irises
Beardless rhizomatous irises
- Iris confusa – Bamboo Iris
- Iris cristata – Crested Iris
- Iris gracilipes A.Gray
- Iris japonica Thunb.
- Iris lacustris – Dwarf Lake Iris
- Iris milesii Foster
- Iris tectorum Maxim. – Wall Iris
- Iris tenuis S.Wats. – Clackamas Iris
- Iris wattii Baker ex Hook.f.
Smooth-bulbed bulbous irises. Formerly genus Xiphion.
- Iris boissieri Henriq
- Iris filifolia Boiss.
- Iris juncea Poir.
- Iris latifolia – English Iris
- Iris serotina Willk. in Willk. & Lange
- Iris tingitana Boiss. & Reut. – Morocco Iris
- Iris xiphium – Spanish Iris, Dutch Iris, Small Bulbous-rooted Iris
Bulbous irises. Formerly genus Junopsis.
Smooth-bulbed bulbous irises known as "junos". Formerly genus Juno.
Reticulate-bulbed bulbous irises. Formerly genus Iridodictyum.
- Iris bakeriana Foster
- Iris danfordiae (Baker) Boiss.
- Iris histrio Rchb.f.
- Iris histrioides (G.F.Wilson) S.Arn.
- Iris kolpakowskiana Regel
- Iris pamphylica Hedge
- Iris reticulata Bieb.
- Iris vartanii Fost.
- Iris winogradowii Fomin
Flowering Yellow Iris (Iris pseudacorus) at a water treatment pond
Iris atropurpurea, one of the dark-flowered Oncocyclus bearded irises
Iris unguicularis flower
Iris pseudacorus in Cheshire in England
Standard Cyclopedia of Horticulture
|Standard Cyclopedia of Horticulture|
Iris Greek, rainbow). Iridaceae. Plates LVIII, LIX. Showy and interesting flowers for outdoor bloom, widely known and planted; perennials with rhizomes or bulb-like root-stocks, mostly narrow long leaves, and commonly erect habit; includes the blue flag and fleur-de-lis.
Herbs with linear or ensiform equitant lvs. : st. simple or branched: fls. of 6 segms., the 3 outer reflexed, and the 3 inner usually smaller and erect, always narrowed to a distinct claw, 1 to many in terminal heads, from spathes which are formed of the upper bract-like lvs.; spathe stalked or sessile: style divided into 3 petal-like branches, which are bifid or crested at the tip; stigmatic surface immediately below the crests; ovary sessile or pedicelled, within the spathe. — Distinguished from the other members of the tribe except Hermo- dactylus and Moraea by the 2-winged style-branches, from Hermodactylus by the 3-celled caps., and from Moraea by the more or less connate perianth-segms. For monographs of the genus, see Baker's Irideae, 1888, Lynch, The Book of the Iris, 1904, and the fine monograph of Dykes, The Genus Iris, 1913. The number of species of Iris recognized by different monographers ranges between 140 and 170. The synonomy includes something over 700 names. The extensive synonomy is an indication of the great variability and wide distribution of the genus. In general the irises are natives of the North Temperate Zone, but the different sub- genera differ much in their distribution. The distribution of some of the subgenera is coextensive with that of the genus, while others are restricted to limited regions. The subgenus Apogon is the largest and also the most widely distributed section of the genus. Its representatives are found throughout temperate N. Amer., Eu., Asia and N. Afr. They extend from Alaska, Labrador and Kamtchatka in the north to Fla., Algiers and Honkong in the south. The members of the sub- genus Pogoniris, which is the second largest and horti- culturally the most important section, are found in Cent, and S. Eu. and N. Afr. and thence eastward to China and N. W. India. No members of this sub- genus are indigenous to Amer. The small subgenus Eyansia comprises a few species of crested irises which, with the exception of the two closely related American forms, I. cristata and I. lacustris, occur only in Japan and E. China. The American species differ widely from the far eastern ones in the absence of an evident stem. The subgenus Oncocyclus is a small section whose members are restricted to a limited region in Asia Minor, Syria, and Persia. Farther to the east, in Turkestan, the Oncocyclus irises are replaced by the members of the closely related subgenus, Regelia. In N. India in the region to the south of the Karakoram and Himalayan Mts. are found a few species constituting the subgenus Pseudoregelia, so named on account of the affinity of its members to those of the subgenus Regelia. The peculiar oriental subgenus Pardanthopsis contains only a single species, I. dichotama, which is found in Manchuria and N. China. The bulbous irises comprise three subgenera, Xiphium, Juno, and Gynandriris. The subgenus Xiphium is sometimes divided into two sections, the Xiphiums proper, which occur in Spain, Portugal, Sicily and N. Afr.; and the reticulata irises, which are found in Asia Minor, Transcaucasia and Turkestan. The Juno irises occur in Spain, N. Afr., Asia Minor, Persia, and eastward to India. The single species of the monotypic subgenus Gynandriris is distributed from Portugal to N. W. India.
Something over 100 species of Iris, with innumerable garden varieties, are offered by dealers in America. Many of these, including the native species, are cultivated only to a slight extent, so that horticultural interest centers chiefly around the groups described below.
1. German irises.—Under this head may be grouped the tall European pogonirises and the numerous varieties and hybrids derived from them. Besides I. germanica which may be taken as the type of this class, the principal species of the group are I. aphylla, I. variegata, I. florentina, I. pallida, I. cengialti, I. flavescens, I. plicata, I. swertii, I. kochii, I. lurida, I. neglecta, I. sambucina, I. squalens and I. hybrida. Many of these which are usually recognized as species are undoubtedly of garden origin. I. germanica itself is not certainly known to occur in a native state. I. florentina or I. albicans is a common ornament in Mohammedan cemeteries and was undoubtedly distributed throughout the Mediterranean region by the Mohammedans, who carried it everywhere with them as an embellishment for graveyards. I. kochii, I. lurida, I. neglecta,, I, sambucina and I. squalens are probably hybrids of which there are innumerable forms in this group. I. swertii and I. plicata are pale forms of I. cengialtii and I. pallida, in which the color is absent except along the margin of the segments. I. hybrida probably represents a similar derivative of I. variegata in which the yellow color is absent. Owing to their diversity of origin, the varieties of this group have a great diversity of color, ranging from pure white through all shades of mauve and blue to dark purple. From I. variegata and I. flavescens the yellow-flowered varieties and those whose flowers are variegated with yellow were probably derived. The flowers of all the varieties are large and handsome, often stately, exhibiting beautiful variegation and shades of color. They are borne on stout, erect, branched stalks much exceeding the clumps of spreading leaves. All are hardy, and form excellent border plants, flowering in May and June.
2. Japanese irises.—All the plants cultivated as Japanese irises are referable to a single species, Iris laevigata, more commonly known as I. kaempferi. The type of the species has been so much broken that its varieties constitute a distinct horticultural group, containing perhaps as many or more named varieties than the germanica group itself. So far as known, no hybrids or other species enter into the make-up of this class. The plants form strong clumps, attaining a height of 2 to 3 feet, and bearing several flower-stems. The leaves are slender, erect, growing almost parallel to each other. In the wild type the inner segments are erect and rather small. The cultivated forms fall into two groups,—the three-petaled forms in which the inner segments have been nearly suppressed while the outer segments constitute the showy part of the flower, and the six-petaled forms in which all the segments are large and spreading giving the flower the flat expanded form characteristic of the group. The flowers range in color from white through various shades of blue to deep purple, with the segments variegated with darker veins and streaks, or plain. All the varieties are hardy, and thrive best in cool, moist situations. They begin flowering in the hitter part of June and continue through July.
3. The tall apogon irises.—Besides the Japanese irises, two other groups of apogon irises deserve mention on account of their ornamental value. These are the sibirica group and the spuria group. The species of the sibirica group which are of horticultural interest are I. sibirica, I. sanguinea, I. wilsonii, and 7. delavayi. The plants of this group are characterized by long grass-like leaves growing in close tufts from which arise clusters of tall branched flower-stems 2 to 3 feet in height. I. sibirica has several varieties ranging in color from deep blue to white. These, with the addition of I. wilsonii. make it possible to have tall clumps of blue, white, and yellow irises of the sibirica type. I. sanguinea, which has the flowers partly hidden among the leaves is less ornamental than I. sibirica, in which the flowers are raised high above the leaves. I. delavayi is a blue-flowered species which flowers in July when most other irises have passed. The plants of this group all thrive best in rather moist situations. Of the spuria group, only the tall ornamented forms closely allied to I. spuria are considered here. The most commonly cultivated forms are I. spuria, I. halophila, better known as I. gueldenstaedtiana, I. orienitalis, I. monnieri and I. aurea. These differ from each other only in minor characteristics such as color and slight modifications in the shape of the segments. They are frequently all regarded as varieties of a single type, I. spuria, but for horticultural purposes it is more serviceable to treat them as separate species. Besides those forms which may be said to approach specific rank, innumerable minor varieties exist in the group. The color of the flowers ranges from blue in I. spuria to bright yellow in I. monnieri and deep yellow in I. aurea. In I. orientalis the flowers are pale yellow bordered with white. The proportion of white and yellow varies much in different specimens. The plants of this group are tall and stately with leaves 1 to 2 feet long, drooping gracefully above. The flower-stems usually rise high above the leaves, and bear two to three heads of flowers. Those on the lateral branches are held close to the main stem so that the whole inflorescence has the appearance of a spike. The stems are usually 2 to 3 feet high. Those of I. aurea are said to grow to a height of 5 feet in California. Some of the species are natives of swampy regions and consequently thrive well in wet places. All grow well, however, in almost any situation.
4. Dwarf irises.—Dwarf irises occur in several sub- genera but the best-known and most commonly cultivated forms are the dwarf European pogonirises, including I. pumila, I. pseudo-pumila, I. biflora, and I. chamaeiris. These are remarkable for then- numerous color varieties, which range from pale yellow to lilac, blue, purple, and very dark red. Most of the forms in cultivation are varieties of I. pumila and I. chamaeiris, but many of the garden forms which pass as varieties of I. pumila are derived from I. chamaeiris. I. pumila and I. chamaeiris are the most satisfactory of the group, as the others are less hardy or less florif- erous. I. arenaria, the Hungarian form of I. flavissima, thrives well in dry sandy situations. The most common dwarf forms among the apogon irises are 7. humilis, I. ruthenica and the American I. verna. Of these, I. verna is the most striking because in all characteristics of habit and growth it resembles a pogoniris but lacks the beard characteristic of that group. I. cristata and its close relative, or perhaps subspecies, I. lacustris, are dwarf American forms belonging to the subgenus Evansia, or crested irises. The dwarf irises seldom grow over 9 inches high. They spread rapidly by their creeping rhizomes and soon form large patches. This habit makes them useful as border plants.
5. Oncocyclus irises.—The oncocyclus irises differ from other irises in several striking characteristics. The seeds have a creamy-white aril nearly as large as the seed itself. The stem is surmounted by a long, unkeeled tubular spathe which reaches beyond the top of the perianth-tube. The stem bears a single flower, which in some species is of enormous size, compared with the size of the plant. The segments, of which the inner are larger than the outer, present a most singular combination of somber colors. The peculiar colors are often due to the interlacing of numerous very thin veins, usually blue or brown, on a white or straw-colored ground. The most common shades thus produced are beautiful sky-blue, light gray, and brown to almost black. In some, all the segments are colored nearly alike, but in most species the inner and outer segments are differently colored. The species fall into two groups according to their geographical distribution. With their distribution other characteristics are curiously correlated. , The species occurring in central and eastern Asia Minor, Transcaucasia, and the mountains of northern and western Persia are dwarf slender species differing from each other by well- marked characteristics. Those found in Palestine, Syria and Mesopotamia are tall, attaining a foot or more in height, and resemble each other so closely that they cannot be distinguished by any characteristic except the color of the flowers. These apparently are all varieties of a single species. In America the oncocyclus irises are not widely cultivated. The most commonly grown form is I. susiana. Many hybrids have been raised in Europe. For a monograph, see Foster, Gn. 43, pp. 130-135.
6. Bulbous irises.—About 20 species of bulbous irises are cultivated in America. They are rather dwarf, hardy and half-hardy bulbous plants, known chiefly for the brilliant colors and strong contrasts, and for their numerous flowers. The species most commonly found in gardens are I. xiphium, better known as I. his- panica, and I. xiphoides or I. anglica. The latter is probably the oldest iris in cultivation. See Foster, G. C. II. 23, pp. 567 and 726, and Foster, Bulbous Irises (1892). Heinrich Hasselbrino.
The cultivation of irises.
As will be seen by their distribution, irises are especially adapted by their hardiness to growth in our gardens, though some forms, as the African, the Indian, and the Oncocyclus species, need special treatment or protection. In the main, the irises, from a cultural point of view, are like others of the various natural families, mostly very good—not to say commonplace— with a few decidedly inferior members. As there are nearly 170 species of irises, with countless varieties, they are interesting to the amateur collector and grower both for their variety and their general beauty of flower.
The life of iris flowers varies from three to six days. They are fragile, but if cut before the petals unroll may be forwarded to considerable distance without injury. This is the only way, in fact, by which the florist can market them. The botanists divide the irises into two main groups, the bulbous kinds and those with rhizomes, these groups being each divided by the varying characters of the more or less raised line in the middle of the fall of the flower. This; of course, gives no clue to cultural necessities or to time of flowering, two important details in a garden.
Considering the bulbous irises as a group, these are all hardy without protection in the latitude of New York city except I. histrio, I. alata, I. juncea, I. palaestina, I. tingilana, I. vartanii.
In the order of their flowering, the reticulata group is the earliest, 7. Bakeriana and others starting into flower as soon as released by frost, usually in February or March. These are soon followed by the others of this group, the largest-flowered member being I. histrioides. A peaty, sandy soil seems to be most acceptable to this group, and no organic manure must be given them. A location, if possible, where they may be kept on the side of dryness in summer is desirable. The culture of these, like that of all exotic plants in our gardens, is, of course, tentative. If, on trial, they seem to be happy and increase from offsets or buds, they may remain in the borders indefinitely, but if during the second season they show no gain, the bulbs should be
lifted and a trial made in another location. This group seeds freely, and the seed-pods will be found just under the soil surface.
Closely following this group are the so-called Juno irises, of which I. persica is the most familiar, though not the best example. These irises have somewhat large bulbs, with curious persistent, fleshy roots, and seem to thrive best in somewhat stiff soil, in sheltered locations, where they will be well baked during the summer. They flower in March and April, the best forms being I. rosenbachiana, I. orchioides, I. sindjarensis, and I. assyriaca. They are desirable plants in the most exclusive gardens. They seed freely, and also increase by offsets.
About the same time as above will flower the Iris tuberosa ("The Widow"), which is neither bulbous nor an iris strictly, but has a weird beauty of its own, with its green and black flowers. This should have a summer baking. See Hermodactylus.
Planted out in the early fall, the so-called Spanish irises make an early start and produce leaves which are persistent during the winter and seldom injured here. In May and June they broaden out, and are then surmounted by very bright, distinct and charming flowers. Very satisfactory flowers, these, and of the easiest culture. They probably do best in spots inclining to moisture. The bulbs make offsets rapidly, and should often be divided and replanted. There are two forms and numerous flowers of this iris. The boldest form is that known as the "Thunderbolt." Spanish irises, under mild forcing are now largely grown by florists for early spring flowers.
The "English" irises, I. xiphioides, follow the "Spanish" in June and July. Their flowers are wider in all their parts, and in a limited range of colors, white and purple. "Mt. Blanc," pure white, is probably the most satisfactory of the group. The foliage of the English iris does not bear till early spring, and the varieties flourish in a rather drier position than the "Spanish."
The African bulbous irises, I. juncea, I. vartanii, I. alata, are subjects for a coolhouse, though the former is rarely hardy here.
The rhizomatous irises may be divided into a number of sections, but in a cultural way may be broadly considered in two sections: those with thick, surface- creeping rhizomes, as the hybrid German, and those with more or less thin ones, as I. sibirica and I. laevigata, which are subterranean. While the former section comprises plants which grow in various conditions, some with the roots submerged, yet in a general way they have mostly surface-creeping rhizomes. These are best transplanted soon after flowering, at which time they commence a new growth. It is customary for the nurserymen to supply these in the fall, which usually leads to the loss of a season, as they often fail to become established when planted late. The foliage of the iris indicates, a sun-loving family, and irises should be planted in full exposure in rich, but not manured soil, well drained. The rhizomes should be planted flat and covered to half their diameter. If the rhizomes are in a growing condition, no further care will usually be necessary with the larger number of the species, but if the rhizomes are dormant and partly dried up as they are frequently on receipt, care should be taken that they have not much moisture till they start into growth, otherwise they are likely to rot. Not every iris will grow in every garden, but the failure to establish these plants is most often caused by too much exposure to excitement of light, warmth and moisture when the plant is not ready to convert its reserve into food. Valuable species should have the protection of a frame in such circumstances till it seems safe to plant them out. If carefully treated and not excited, apparently hopeless dried-up rhizomes may often be saved. Most of these irises in common cultivation increase rapidly, and should be divided and replanted every two or three years; otherwise the rhizomes become matted and the abode of grass. Among them will be found some of the showiest flowers of the family.
Usually in early May I. chamaeiris and its variety I. olbiensis flower, followed quickly by the dwarfer I. pumila and its white form I. attica. Forms of I. lutescens, Lam., quickly follow, after which I. germanica, I. florentina and the host of "hybrid German" varieties come rapidly forward and give a great wealth of color. Everyone is familiar with the great bearded purple I. germanica, perhaps the most generally cultivated iris. There are larger-flowered forms of this: I. amas and I. macrantha. I. germanica alba seems to be a variety of I. albicans. This and I. florentina are the usual white-flowered forms seen at this time. Of bold, lighter purple kinds, I. pallida and its hybrids are then preeminent.
The German irises of the garden are not varieties of I. germanica, but hybrids of various species, as I. pallida, I. variegata, I. sambucina, I. squalens, I. lurida x wild forms and I. neglecta, I. amoena, I. plicata and I. swertii, which are known only in gardens. Naturally these vary much in stature, time of flowering, size and coloring of flowers. They may be had in almost endless variety, but a typical collection may be made with comparatively few plants.
Among the best forms of the "hybrid German" irises are: I. aphylla—Bridesmaid, Madame Chereau, Swertii; I. amoena—Compte de St. Clair, Fairy Queen, reticulata alba, Victorine; I. neglecta—Cordelia, Wagner; I. pallida—Khedive, Mad. Pacquitte, Queen of May, Walmer: I. squalens—Arnols, Jacquiniana, Harrison Weir, Mons. Chereau; I. variegata—Beaconsfield, Darius, Hector, Honorable, Prince of Orange.
June is flowering time for many iris species, many of which are uncommon, but of the more available forms one could scarcely neglect the native I. hexagona, the dark La Mance form of which is very distinct and amongst the handsomest of the family. A white form of this is not hardy here. I. fulva, another native plant with copper-colored flowers, is also interesting. Irises with distinct forms are I. monnieri and I. orientalis (or I. ochroleuca), both of which have obliquely growing rhizomes and enjoy moisture.
For margins of water I. pseudacorus, with yellow flowers, is invaluable, and our natives, I. versicolor and I. caroliniana seem as happy in the moisture as in the uplands. The iris rhizomes which require deep planting are mostly smaller and thinner than those of surface creepers. The species with these roots are mostly strong-growing plants, rapidly increasing and requiring an abundance of moisture, though there are some notable exceptions to be mentioned later. Of the members of this group, I. sibirica, in several purple and white forms, is a common garden plant. I. ensata is a common Asiatic iris with small flowers borne among the narrow foliage, which is as ornamental as some of the large grasses.
The Japanese irises, which usually end the general display of irises, are a remarkable example of type- breaking, the occidental gardeners having worked up from I. laevigata a wonderful variety of colorings and variation in number of petals, though the colors may be included in about half a dozen general types. There are few handsomer flowers than good forms of the white Japanese iris. This iris may be grown on the upland, but it does not do its best in such locations, for it is particularly susceptible to good treatment, and to produce large flowers both water and manure are essential. Peter Barr, the veteran fancier of good plants, wrote from Japan, after consulting one of the oldest cultivators, that "this iris is grown in the rice-fields in winter and watered each month while at rest with human manure (cow manure would do); as soon as young growth appears no more manure is given and
the ground is flooded. When growth has ended the water is withdrawn."
One of the most curious things in connection with the Japanese iris is that though these plants have been in cultivation here since soon after the treaty ports were first opened, they seem to have excited little attention from gardeners until within a few years. Yet the first importations were as handsome as the later. In this connection it may be said that Japan has also I. gracili- pes, a dark purple hardy form, and I. japonica or I. chinensis, one of the beauties of the family but, like I. tectorum (the roof iris), another crested kind, needing here greenhouse protection and well worth it. There is. however, a perfectly hardy crested iris, the beautiful dwarf I. cristata of the upper southern states—a charming plant for a front border or rockery. Equally dwarf are our lake irises I. lacustris and I. verna.
The west coast of the United States is fortunate in possessing some beautiful and distinct irises, mostly of the wiry-rooted, thin-leaved type. They have not yet been fully separated botanically, and they are most difficult things to establish in eastern or other gardens, so that there are really very few in cultivation.
I. macrosiphon, I. hartwegii, I. douglasiana, I. bracteata, I. tenax, I. longipetala, I. tennis and I. purdyi is a list which will interest the searcher after interesting plants. Max Leichtlin, who has a genius for growing difficult things, has been successful in establishing I. bracteata, I. macrosiphon and I. purdyi. He says, "My experience is that they cannot be moved unless in full vegetation. We must grow them from seed, and not touch the seedlings until they have formed a solid rootstock. After this and movement to grow has begun, they can be safely handled and transplanted like other irises."
Seed should be sown in the open in autumn, plants appearing in the spring should be undisturbed, and in the fall covered with a frost-proof frame. They should flower the second (or third) season. After flowering they may be shifted carefully, but must always have protection as they naturally commence to grow very early and frosts are fatal to them. Only in this way is there much chance of success with these rare plants. Some of the species have been flowered here under harsh conditions but they were survivals of large numbers of collected plants.
There remain to be considered two allied groups, the oncocyclus and regelia. These are considered by amateurs the most interesting groups of the iris family—interesting in the amateur's vocabulary meaning something rare and difficult. At the best, these plants give few flowers, but they compensate for this by their distinct and quaint beauty. The best known member of the family, I. susiana, has been in cultivation several hundred years, but is by no means yet a common plant. It takes more kindly to cultivation than any other of the groups, will usually flower in the border the first year after planting if the spring is not too rigorous; and gardens are not unknown where, from some conditions of fortunate placing or soil, they continue to flourish. It cannot be said that there is any hard and fast formula for growing these irises. They vary among themselves as to their requirements, and need special and different treatment in different gardens and climates. These irises are natives of Palestine, Asia Minor, the Caucasus, central Asia and Persia regions, all of which are hot and dry in summer, with a settled and sometimes severely cold winter and a genial spring. In some of the regions they are protected on a covering of snow in winter while dormant, but Palestine and Persia have open winters, and their irises make growth at this time. After cultivating most of the species for a number of seasons, the writer's experience does not lead him to dogmatize much on their cultivation or to approve of many special devices which have been put forward from time to time as the solution of the problem. The consensus of opinion among the growers who have had the best success with these plants is about as follows, premising that one is dealing with plants which are perfectly hardy: The rhizomes are received with the Dutch bulbs in the fall, at which time they are dormant and leafless. It is well to store them in a cool place and plant out in November in a bed of fairly light and well-drained soil in a border fully exposed. They require no protection, but if the climate is one where frosts and thaw alternate, it is well to give the ground a covering while frozen to keep it firm. The irises so planted will seldom spear here till genial weather arrives, and with plentiful supplies of moisture at the root will give flowers from strong buds. After flowering, or more accurately, flowering time, one is forced to choose between two methods of treatment. If the garden is high, dry and hot, the best procedure is to cover the beds with a glass frame sufficiently large to protect them from moisture and allow the rhizomes to bake. This frame may be removed in the late fall. If the leaves appear, as some of them are likely to do, they may be left unprotected until very severe weather sets in, that is, usually in December. Coal-ashes have also proved satisfactory, though unsightly. Foliage does not seem to become as soft under them as under leaves or mats. If the spring is genial, with weather steadily becoming warm, the plants, being uncovered as soon as the conditions will seem to warrant, should be in the best possible shape to reward one with their noble blooms. It is the lack of this genial spring in the latitude of New York which, however, leads often to cultural troubles. The leaves, having been protected, are none too hard, and, with the constant alternate thawing and freezing, and the high winds, hot and cold, the plants need constant watching and application of needed covering till really genial weather. Otherwise the foliage is blighted and no flowers are produced. The most satisfactory way, if one is more interested in results than in garden problems, is to grow oncocyclus and regelia iris and the numerous hybrids which are now available continuously in a coldframe. The frame should be located where drainage is perfect with no bottom moisture, so that the plants may be kept perfectly dry and baking after the blooming season. The plants should be protected from hard freezing after leaves are formed, but should not be protected enough to make them soft. The trouble of this procedure is well worth while if one wishes a rare display.
In gardens which are low and never free from moisture, the best procedure is that followed in Holland, lifting the rhizomes in July and taking them under cover in dry earth, planting out again in the fall. In this case care should be used in lifting not to injure the numerous fleshy roots. The Palestine and Persian forms of these irises are considered the most difficult to cultivate, from their habit of early growth.
Irises are not only increased by the division of the rhizomes or by offsets, but may be rapidly grown from seed, which they usually produce freely, though, in most cases, they require artificial fertilization. A large number of the common irises of gardens are hybrids, and of late years a number of beautiful hybrids have been produced between some of the rarer oncocyclus species, and between these also and common forms, as I. variegata, and so on. There are still opportunities to produce many new and untried crosses, and experiments in this line are recommended. The pollination of the iris is simple. The anthers should be removed when the flower first opens, and preserved in paper or vials, properly marked. The pollen will retain its potency for a week or perhaps longer, and may be applied to the stigma of the flower selected (the anther of which has been removed promptly) with a camel's-hair brush. The stigma will be found near the apex of the petal-like style, and is ready for pollination when the upper edge drops down and exposes the upper surface. Many iris
seeds germinate with considerable irregularity, and failure to start promptly should not lead to discouragement or discarding of the pan in which the seeds are sown- J. N. Gerard.
The iris in California.
Because such a large proportion of the iris come from around the Mediterranean and so are accustomed to a thorough baking and drying out in summer, their culture is especially satisfactory in California and the range of varieties available so large that some may be found in flower in all but the late summer months. The first rains usually start a few of the dwarf and tall bearded iris into a premature flowering, this being so regular in the case of the Iris kochii that it is now being sold as a fall bloomer. I. stylosa (I. unguicularis) also flowers in the fall and early winter, accompanied at the latter time by the smaller bulbous irises, such as I. reticulata. From February on, the dwarf bearded irises (I. pumila and the many slightly taller forms of I. chamaeiris) are covered with masses of flowers in various shades of cream, yellow, blue, and purple. In March and April one has a choice of the tall bearded or so-called German iris, the oncocyclus group, I. spuria, I. ochroleuca, I. aurea, I. monnieri, and their cross-bred relatives, as well as the native Californian species and the moisture-loving Siberians. May sees the Spanish irises at their best, followed toward the end of the month by the English iris, and the season ends in June or July with the big Japanese.
The cultural directions for California are simple, varying somewhat with each main group. The tall bearded varieties grow so easily and are so clean and so nearly evergreen that the type (I. germanica and its white form) is often used for planting between sidewalk and curb. Yet the many beautiful kinds to be found in the I. pallida, I. plicata, I. neglecta, I. variegata, and I. squalens sections are not very often seen, although their culture is quite as easy. All they require is sunlight and a place which becomes quite dry hi the summer, the easiest possible conditions to supply in California. They dislike shade and standing moisture. Soil is not important, as equally fine results have been secured in the heavy adobe of the valleys and in gravelly hillside loams. Divide to single rhizomes and replant when they show signs of being crowded. This is best done just after blooming or in late summer, but it is possible at any time of the year.
Next to the above, the bulbous Spanish irises give the best garden effect and lead in usefulness as cut- flowers. The little bulbs should be at least 3 inches underground by October, if possible, as they dry up if left too long before planting. Distance apart is a matter of taste, but they may go as close as 3 inches if space is valuable, and may even be used as a top crop between tulip or daffodil bulbs to keep up the show in a small garden. Plant in any cultivated soil, but see that drainage is good, as the stems rot off if subjected to stagnant water. After blooming, do not cut the stems to the ground if flowers are desired next year, for the slight foliage is needed to ripen the bulbs. Many of the best varieties, however, are so cheap that where ground is valuable they may be discarded after blooming, though if left to ripen properly they will increase so rapidly that division will be necessary every other year. English irises are not nearly so satisfactory, though their flowers are larger. They need much more moisture than the Spanish irises, and are more to be recommended to those who can give plenty of water and partial shade.
The oncocyclus and regelia irises do better in California than anywhere else hi America, as they must be dried off in summer and no artificial means are necessary here. Contrary to European practice, the best success is achieved by planting as soon as received in October and encouraging growth so that the plants will be ready to bloom in March and April. No special soil is recommended, but it is desirable to cater to their lime-loving taste by incorporating old plaster and bone- flour in the earth. They are nowhere easy plants to grow, so, if success be achieved the first year, leave the roots alone. Under these conditions, I. susiana, I. atrofusca, I. iberica, I. lortetii, I. korolkowii, and others bloom quite well. The Juno irises do fairly well under these same conditions, but are still rather an experiment.
Most striking features of many gardens in April are huge clumps of I. orientalis (I. ochroleuca). For culture these can be grouped with I. spuria, I. aurea, and I. monnieri, as all like lots of water during their growing season, which is fortunately our rainy one, but again somewhat contrary to experience elsewhere they can get through the dry season without irrigation.
The Siberian and Japanese iris, however, need moisture as much here as elsewhere, and, though the amount required may be lessened by heavily mulching the bed with rotten manure, they are certainly less adapted to our natural conditions than the other sections of the genus. In the warmer, sunnier parts of the state, the flowers often burn badly and have to be protected with lath screens, an unsightly arrangement. Their most suitable place is in a Japanese garden where they can get the overflow of a pool, and if this is in the summer- fog belt they are quite satisfactory.
The Californian iris are well worthy of garden cultivation, I. douglasiana, with its range of color from purple through lilac to buff, being especially attractive. Do not dig up the wild plants when in bloom, as they will not move well at that time. Either raise from seed or lift them when growth starts in at the beginning of the rainy season, this being the only safe time to move any of the native species.
Twenty-five distinct tall bearded irises for California, omitting only expensive novelties:
Asiatica (Kharput), amas, Kochii.
Pallida, pallida dalmatica (Princess Beatrice), Albert Victor, Queen of May, Madame Paquette.
Madame Chereau, Mrs. Reuthe.
Mrs. Horace Darwin, Victorine (weak grower), Isolene.
Perfection, Cottage Maid.
Darius, Gracchus, Hector, Mrs. Neubronner.
Jacquesiana, King of Irises.
Cengialtii, florentina, flavescens, Cypriana superba. Sydney B. Mitchell.
Orris-root (corruption of iris-root) is apparently the product of I. germanica and related species; the violet scented roots are used for perfumery powders, dentrifices, and for bad breath; the "fingers" made from the rhizomes are used for teething babies.
As orris-root is no longer used for artificial violet, the price has receded to normal, and probably if grown in this country would not pay. However, as it is likely to be of interest to the public and experimenters, the following notes are quoted from L. J. Keena, Florence, Italy, in a commercial publication.
"The soil in which this root is grown has much to do with the quality, as well as with the quantity and fragrance of the root, and therefore with its commercial success. This plant grows in different kinds of soil, but that best adapted to its growth is the stony mountain soil. This, however, must be scientifically prepared so that the under soil will not remain compact, for that would be disastrous to the plant during the summer months. In a loose soil containing sand the roots grow well, but are less odorous and compact. Rich yellow soil is still less adapted to its culture, as the plants die quickly. The rich land near manure-piles produces a great quantity of plants, but the roots are neither of good quality nor fragrant, and when dried shrivel up and are consequently discarded by the buyers. The situation or lay of this land matters little, though the best ground is usually found on hillsides. The plant also grows high up in the mountains, where snow and ice make the cultivation of it difficult. In these high places the root takes a few years more to reach its full growth.
"The most suitable soil for orris-root is that which has been prepared by spring seeding with some variety of leguminous plant, and which has been well prepared and deeply plowed. The best months for planting the iris are August and September, although it may be planted as late as the first part of October. The first two months mentioned, however, are preferable for the planting, as the plant begins to grow immediately upon being placed in the ground.
"The best method for planting in soil that has already been prepared is to make holes with a hoe about 16 inches apart, beginning at the bottom of the hill One plant should be placed in each hole resting on the wall of the hole and having its root just reach the bottom. This permits the perfect development of the bulbous root. To insure good production, the soil should be hoed in May and again in September. Irrigation is not beneficial to the plants, as the roots become less compact in irrigated land and there is a dangerous tendency toward fermentation. Fertilizing the soil with manure has the same effect, but if the production of a large number of plants is desired, a system of fertilizing with rich soil can be adopted. The best fertilizer is the seed "lupino" (Lupinus albus), which, after being cooked in an oven, is placed in small quantities near each plant at the September hoeing of the first year, if it is to be a two years' growth, and in September of the second year, if for a three years' growth. If the field is to be replanted with orris-root the soil should be well fertilized, and grain, grass or some other crop grown thereon for three or four years.
"The gathering of this product begins during the last fifteen days of June, and is carried on in the following manner: Several men hoe out the plant as a whole, distributing only so many of the plants as can be handled by the rest of the force during the following day, because the plants dry quickly when exposed to the sun and wind. The plants are then carried to a shelter, where the bulbous part of the root is cut off, care being taken to leave enough of the root extensions to insure a good growth for the following years. The bulbous root is then cleaned and scraped free of all imperfections. After the scraping, it is washed by hand in a succession of basins of running water.
"The roots for market are then dried in the sun, with provisions for covering and protecting from the ruinous effects of rain. It is well to set the roots outside before sunrise in order that they may receive the bleaching effect of the dew. After eight days' exposure to a strong sun, the orris-roots can be taken in under cover and packed in a dry place. Preferably the roots should be pulpous and as white as possible. Artificial drying in ovens or in any other manner depreciates the value of the product by making it less than if sun-dried. In the drying process the weight of the root becomes two-thirds of what it was when cut from the plant."
acoroies, 73. acuta, 65. alata, 89. alba, 3,6,25,65,67. alberti, 24. albicans, 25. albopurpurea, 84. amoena, 31. anglica, 100. aphylla, 14,20,21. arenaria, 11. aschersonii, 57. asiatica, 19. assyriaca, 96. atrofusca, 49. atropurpurea, 6,30, 44, 49. atroviolacea, 6, 18. attica, 6. aurea, 81. azurca, 6. bakeriana, 108. balkana, 10. barnumae, 42. battandieri, 99. benacensis, 14. bicolor, 6. biflora, 8. biglumis, 61. biliottii, 26. bismarckiana, 51. bloudowii, 11. bohemica 14. boissieri, 102. bornmuelleri , 86. bosniaca, 10. brachycuspis, 77. bracteata, 68. caerulea, 6, 94, 105. candida, 3. caroliniana, 76. caucasica, 92, 94, 98. cengialti, 13. chamaeiris, 9. chinensis, 3, 5. chrysantha, 41. caelestis, 6. concolor, 37. cretensis, 67. cristata, 1 , 3. cuprea 72. cyanea, 105. cypriana, 29. danfordiae, 86. darwasica, 38. delavayi, 63. desertorum, 83. dichotoma, 52. douglasiana, 70. eggeri, 44. ensata, 61. erratica. 7. ewbankiana, 46. falcata, 14. fieberi, 14. filifolia. 103. fimbriata, 3, 5. flava, 73. flavescens, 22. 23. flavissima, 11. flexuosa, 65. foetidissima, 82. fosteriana, 93. fragrans, 8, 61. fulva, 72. fumosa, 97. furcata, 14. gatesii, 47. germanica, 30. gigantea, 80. gracilis, 6, 14, 66. grant-duffii, 57. gueldenstaedtiana, 79. haematophylla, 61, 64. halophila, 79, 83. hartwegii, 56. haussknechtii, 87. haymei, 49. heldreichii, 87. helenae 43. hexagona, 75. hispanica, 99. histrio, 106. histroides, 105. honorabilis, 15. humilis, 53. hungarica, 14. hybrida, 31. iberica, 40. imbatrica, 22. intermedia, 81. italica, 9. jacquesiana, 34. japonica, 5. juncea, 101. junonia, 28. kaempferi, 84. kochii, 17. kolpakowakiana, 109. korolkowi, 37. krelagei, 105. lacustris, 2. laevigata, 84. leichtlinii, 36. lineata, 38. longipetala, 62. longispatha, 61. lortetii, 48. lupina, 45. lurida, 16, 45. lusitanica, 99. lutea, 6. lutescens, 9. macrosiphon, 55. madonna, 25. major, 50, 105. mandschurica, 12. mariae, 43. maricoides, 110. milesii, 4. minor, 11. missouriensis, 71. monnieri, 78. nazarena, 51. neglecta, 32. nepalensis, 30. nertschinkia, 64. nikitensis, 59. notha, 83. nudicaulis, 8, 14. obtusifolia, 22. ochroleuca, 80. oculata, 98. olbiensis, 9. orchioides, 94, 98. orientalis, 64, 80. oxypetala, 61. pabularia, 61. palaestina, 90. pallasii, 61. pallida, 19, 73. panormitana, 7. paradoxa, 39. persica, 87. plicata, 20. prismatica, 66. psuedacorus, 73. pseudo-pumila, 7. pumila, 6. purpurea, 87. reichenbachiana, 10. reichenbachii, 10. reticulata, 30, 105, 106. rosenbachiana, 88. ruthenica, 53, 54. saarii, 45. sambucina, 33. sanguinea, 64. sari, 45, 51. scorpioides, 89. setosa, 77. sibirica, 64, 65. sicula, 19. sieheana, 87. sikkimensis, 35. sindjarensis, 96. sintenisii, 69. sisyrinchium, 110. sogdiana, 83. spectabilis, 99. sprengeri, 46. spuria, 83. squalens, 34. statellae, 7. stenophylla, 87. stolonifera, 36. stylosa, 67. subbiflora, 8. sulphurea, 6. superba, 30, 67. susiana, 50. suworowi, 38. swertii, 21. tauri, 87. taurica, 6. tectorum, 3. tenax, 60. tingitana, 104. tolmieana, 71. tripetala, 77. trojana, 27. unguicularis, 67. urmiensis, 41. urumovi, 69. vaga,36. variegata, 15, 65, 73. vartanii, 107. verna, 85. versicolor, 74. violacea, 6, 37. virescens, 9. virginica, 66, 74. warleyensis, 95. willmottiana, 91. wilsonii, 58. xiphioides, 100. xiphium, 99, 104.
- ↑ Manning, John; Goldblatt, Peter (2008). The Iris Family: Natural History & Classification. Portland, Oregon: Timber Press. pp. 200–204. ISBN 0-88192-897-6.
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963