(1907) American Irises by George B. Mallett

Gardeners' Chronicle p.417, June 29, 1907

AMERICAN IRISES.

WHILST there is no lack of interest taken in the Irises of the old world, particularly those of the bearded group, other species from the Continent of America are but little known, and so for as cultivation is concerned are as little understood. They all belong to the Apogon (or beardless) group, and the species are remarkable for their great diversity of form and colour, puzzling to the systematist, but a source of delight to the plantsman. He finds in their variable characters just that element of uncertainty and change that gives zest to all pursuits; for every bad form he may get there is a particularly good one as compensation.

The Irises indigenous to America, so far as my studies of them show, are more than usually well distributed. A species may spread over several districts and will vary in each district – a rule of " one district one form " prevailing. This character is mainly responsible for such confusion as now exists in the nomenclature of American Irises, and such confusion will continue to exist so long as colour variation in relation to Irises is given such little consideration as it receives at present.
There is now before me a bed of seedlings of Iris Watsoniana flowering freely. There are no fewer than 14 distinct varieties in a given 100 plants, and the range of these alone connects Iris tenax with I. versicolor in an unbroken chain. In other species it is possible to find yellow or blue flowers of the same specific type. Such variation has its disadvantages as well as its advantages, and the best one can do is to accept " species " of American Irises as collections of forms that agree with each other in some important character.
Their value in gardens has never been realised. Some of the species and varieties are charming plants of easy culture that one can recommend as the equal of many Eastern species., and in one or two cases there is a colour scheme as unique as it is beautiful. Their cultivation cannot be described in a few words. There are water plants among them, plants suitable for the flower border, for the cool house, and for the rock garden. There are some that will not thrive in any kind of garden, but live only long enough to perfect a flower that would bafile a clever artist to portray, and then disappear. For these there is but little to be said, but fully three-fourths of the American Irises can easily be reared and grown, and the garden would be considerably the richer if all of these were included within its boundaries. Quite young plants should be used in starting a collection.

Species and Varieties.

I. BRACTEATA. – It IS Scarcely possible for an Iris to have a more beautiful flower than this, and probably so bad a constitution. It forms a hard, running rhizome bearing a few very slender, sickle-shaped leaves less than half an inch wide, the margins of which are distinctly horny. There is hardly any flower stem, the long tubes serving instead. Three flowers are produced from each rhizome, and they have slender yellow tubes 8 inclies long and half enclosed in broad foliaceous bracts. The broadly lanceolate " fall " petals are 4 inches long, the standards equalling these in length, but being only half their width. I have two specimens before me. One is of a greyish-lilac tint, the other is a lovely flower of pale buff-yellow suffused with amber and very elegantly traced with palest lilac on the falls, the lilac lines merging into purple at the bend of the fall and into transparency at its tip. Rarely have I seen a flower so beautiful as this. The plant is of slow growth, requiring a dry and rich soil, and to be grown between boulders on a rocky slope or in some sheltered corner, thrusting the roots as deeply into the soil as they will go. Only very young plants may be transplanted safely.

I. CAROLiNiANA. – I have not seen living specimens of this species.

I. CRISTATA. – The little marsh Iris from the south-eastern U.S.A. has long been cultivated. It has running rhizomes that secure for the plant a fresh site every year, broad Pea-green leaves that are an ornamental feature all the summer long, produced in fan-shaped tufts a foot high, and the pretty sky-blue flowers are borne early in June. The flowers are but 4 inches high and 3 inches across, the style crests are daintily fringed, and the golden yellow markings on the falls are very beautiful features. This plant is closely allied to tlie tender Iris japonica. It grows best in wet mud or stony soil overlying mud, with its root-stock a few inches above water level. Once established it will bear frequent submersion of the root-stock, and will often extend its growths to the water's edge. It is an ideal plant for the bog garden and the rock pool.

I. DOUGLASiANA. – This very distinct and attractive species can be grown in any good garden soil. It is a long-lived plant with evergreen leafage of a deep bronze-green in fan-shaped clusters. The flowers average two from each slightly flexuose stem, and they nestle among the foliage. The tubes are twice the length of the stems, the petals are coloured creamy-white in the specimen before me, heavily suffused with lilac-purple around the creamy, purple-veined signal patch, and the standards and style branches are coloured a beautiful shade of creamy-grey. A very attractive Iris whose flowers average 5 inches in diameter and wliose margins everywhere are delightfully frilled and waved. It is very variable. Forms occur which approach a self purple in colour ; others are practically all cream coloured witli a trace of lilac here and there. A good garden plant that one can heartily recommend.
The variety known as picturata is a selection which has a white signal patch similar to that of Iris tridentata.

I. FULVA (I. cuprea). – This old species is in many respects a remarkable plant. Botanically it connects Iris with Moraea. Its colouring is a lovely copper-maroon, heavily lined with yellow along the claw. The fall petals are twice the size of the standards, but all agree in their colouring ; the style branches alone show a lighter tint. It is a marsh species, delighting to grow with its feet in water, and its rhizomes bedded in mud. The leaves are produced in handsome clusters 2 feet high, and the flower stems overtop these in June, and flower in July. A warm position and liberal supplies of water are very necessary for the plants, and they grow splendidly in some stagnant mudbank that absorbs heat during the day. The stems are markedly flexuose and branch freely, yielding six to eight flowers, each 4 inches across, the spathulate falls suggesting those of Moraea.
I have seen many flowering specimens, but none showed divergence from the typical copper-maroon. It has been considered tender, but will survive any English winter if well grown. It is a poor plant under the drier conditions of a flower border.

I. HEXAGONA is One of the giants of its race. It has broad leaves and sturdy rhizomes suggestive of Acorus calamus. The flower stems are 5 feet high, markedly flexuose, bearing three to four flowers each, coloured a deep sky-blue with orange tracery at the bend of the horizontally poised claw, and averaging 5 inches across the flower. It comes from the Southern States, where it grows in marshes and swamps. It is too tender to withstand our winters unharmed, but may be grown in a cool house, potting it liberally and allowing plenty of room forward of the growing point. The rhizome makes a growth a foot long annually, and as many leaves are produced it is preferable to stand the pots in pans of water throughout summer. Its hexagonal fruits hang by flexible tubes to the flower stem and resemble the fruit of Passiflora in size and habit, but not in shape. The variety alba has white flowers with paler signal patches. It is of weak growth compared with the type.
Another variety known as Lamancei is a hardy variety that thrives apace in bog earth or by the waterside. It has the running rhizome of the type, but shorter leaves and stems. These latter are markedly flexuose, barely 18 inches high, and bear lovely, blue flowers that are like glorified flowers of Iris tectorum, having a similar colour scheme. It is a very beautiful Iris that soon makes giant clumps. G. B. M.
(To be continued.) Gardeners' Chronicle p.6, July 6, 1907

AMERICAN IRISES. (Concluded from page 417.)

I. Hartwegii. – This plant will challenge the cultivator's best skill and finally disappear. It is a very attractive plant, with slender leaves of a greyish tint produced in dense thickets. The flowers are 4 inches across, coloured pale yellow with lanceolate falls, horizontally poised. The standards are erect and nearly as large as the falls. The plant is capable of lingering for a few years in a pot under cool house treatment, but is quite an intractable plant in the open garden.

I. lacustris. – A small-flowered species, with broadly fan-shaped leaf clusters 6 inches high, and a succession of lilac-crested flowers that are somewhat smaller than Iris cnstata but similarly coloured. It is pretty but very difficult to manage. It is essentially a rock plant.

I. longipetala. – This species and its variations afford a type of Iris that is equal to the best for cultivation in the flower border. The root-stock is a vigorous rhizome that branches freely. The leaves are 2 feet long, narrow, erect, and pointed at the tips. The flowers are borne in threes on slender, erect, rarely flexuose stems, and they are as elegant as they are beautiful. The fall petals are horizontally poised, broadly spathulate or lanceolate, and 6 inches long. The standards are shorter and narrower, and are erectly held, and the margins of both are undulating. The colour is mainly lilac, deeper as regards the standards, but the falls are paler and have a most elaborate veining of deep lilac over every part of the surfaces. There is a slight orange suffusion at the bend of the blade and some yellow down the claw. A very lovely species which must be seen to be fully appreciated.
The variety montana is smaller in all its parts, and the leaves are shorter. This plant is the I. longipetala of gardens, and the variety superba, also of gardens, is typical of longipetala. There are several forms in cultivation, but none is worthy of a distinct name. Ordinary soil and the treatment of common border plants suffices to keep this lovely Iris in good health.

I. macrosiphon. – A rare species of surpassing beauty and very variable. The leaf growth is that of I. bracteata, and the flowers differ only in their colour scheme and in the greater length of the falls. The stems average 9 inches in height ; the flowers exceed 6 inches in diameter and vary in colour trom pale to deep purple-violet in some varieties, and from lilac to buff-yellow in others. All have the characteristic long, drooping falls. It is a very difficult plant to grow successfully in a plant border, but would succeed wedged between stones on the rockery where ample drainage is possible. The variety flava is a pale yellow selection.

I. MlSSOURIENSIS (I. TOLMIEANA). – This species is a useful and attractive plant of proved garden worth, and one that can be recommended for planting in borders. The leaves form glossy thickets, and are about 18 inches high. The flower-spikes just overtop these in early May, and produce a quantity of blooms agreeing in shape with those of I. longipetala montana. The falls are horizontally poised, and are coloured mainly with lilac. The general aspect of the flower is that of a poor, short-petalled bloom of I. longipetala, with a whitish signal patch in the paler varieties and yellow in the deeper-coloured forms. This species embraces at least 10 forms that differ considerably from each other; some are so close to certain types of I. longipetala that the only guide to their specific dlifference is their periods of flowering, which, in the case of I. missouriensis, is a fortnight the earlier.

I. Tollong is a hybrid between I. missouriensis and I. longipetala. Its flowers partake of the characters of the latter parent, but are smaller, more freely produced, and they precede I. longipetala in flowering by ten days.

I. prismatica (I. gracilis). – For several years I had under cultivation a charming miniature Iris under this name. It has leaves just a foot high, slender, and very numerous. The flowers are coloured a clear violet as regards the falls, standards, and style branches, but the blade of the falls is contracted and coloured orange, lined with blue. Iris graminea is akin to this plant in habit and colour scheme, but whereas the leaves of I. graminea hide its flowers, the reverse is the case in I. prismatica, for the foliage is hidden by its flowers. A desire to increase this plant by division of the clumps proved disastrous, for the plants all died. It is a very charming Iris, not markedly showy individually, but the flowers are exquisitely formed and coloured.

I. Purdyi. – This is a vigorous plant of recent introduction, and one whose flowers resemble those of I. versicolor in shape, but are coloured a rich blue and are singularly true to colour. The leaves are slender, grass-like, erect, and are arranged in fan-shaped clusters of from 10 to 12. The stems exceed 1 foot in height, and bear several flowers each. The falls are coloured pale blue with violet margins, and a patch of white occurs at the bend of the blade. The standards are half the size of the falls, and the whole flower averages 4 inches in diameter. It is a very showy plant, easy of culture, and suitable for the plant border.

I. setosa (I. brachycuspis), a native of Eastern Siberia, has one Canadian offshoot in its variety canadensis. The type plant has all the characters of the American group, and may fittingly be known and described with them. It has broad, deeply green leaves, produced in sturdy fan-shaped clusters ; curious flexuose stems a foot high, that bear three to four flowers each, in which the standards are greaty reduced. The broadly spoon-shaped falls are drooping, and as large as a crown piece; they are coloured a rich wine purple, while the style branches have a purple-coloured median line on a greyish ground colour. The species grows well in any soil of good tilth, but it resents disturbance at its roots. The Canadian form has narrower falls, and the colour scheme is altogether paler, with a larger signal patch of white. I have not had the type from Canada.

I. tenax. – Perhaps the most tractable, as it is the most beautiful, of all the American Irises. The leaves grow in graceful tufts, and are 2 feet or more long. The rhizomes cross and recross in the manner of Twitch and take complete possession of the soil. The flowers are borne on slender and nearly straight stems, 2 feet long, and are coloured rosy-lilac, pale lilac, or silvery grey with lilac shading. The falls are sub-erect with recurving tips, and are generally one or two shades deeper in colour than the standards. The margins of all the petals are daintily waved, and there is a large signal patch of white elegantly veined with rosy-purple. This species is very variable in colour, but the form of the flower is practically the same in all. This Iris will grow well anywhere ; the only soil it will not succeed in is one of wet clay.

I. tridentata (I. tricuspis, I. tripetala, I. Douglasii pygmaea, I. Hookeri). – A free-habited plant that grows well by the waterside or in some other damp spot. It has short tufts of deep green, and very broad leaves that are practically evergreen. The flowers are produced in three's, from branching, well-leaved stems that just overtop the foliage, and they are coloured blue, with cloudy markings of purple on the falls. There are practically no standards, for these are reduced to tiny colourless processes. The blade is orbicular in shape, 2 inches across, and the bend of the blade and the claw is lined' with purple, white, and yellow. The style branches are coloured pale amethystine-blue and they are much depressed. It is a floriferous, showy, and attractive plant, suitable for the flower border. Iris Hookeri, considered synonymous with I. tridentata, is a variety of the latter ; the vegetative system of the variety is much stronger, and approaches in habit Iris siberica orientalis, but with no standards.

I. verna. – A very pretty plant that needs a marsh or a cool recess at the margin of a rock-pool for its accommodation. It has a running rhizome, greyish-green leaves and deep blue fragrant flowers, which measure about 4 inches high and possess a very remarkable throat of orange colour. It is one of the gems of the world's flora, and holds a position among grassy- Irises similar to that held by Gentiana verna among Alpine plants. It is an old plant, but still popular, and is likely to continue so as long as gardens exist.

I. versicolor. – A very variable spec'es, whose flowers are not unknown to the English cottager. By a singular inversion of the circumstances, the variety virginica is recognised in gardens as the species, and I. versicolor is labeled as a variety of virginica. It is the commonest Iris of the New World, and extends over many of the States. The leaves are broad, handsome, and arranged in dense thickets ; the flowers are produced just above the foliage on branched stems 2 feet high, each stem yielding a dozen or more flowers. These are coloured a rich wine-purple, shading to carmine at the bend of the blade, from whence a conspicuous shaft of white runs nearly to the tips. The erect standards are half the size of the falls, and they are coloured a pale claret-red. The style branches are white, suffused with pale purple. There are hundreds of forms ; in fact, collected seeds yield almost as many varieties as plants: some are bad, many are good. A few have distinct names, but their seedlings may surpass them. The following are the best known varieties:
I. v. var. virginica (caurina). – A purple-blue selection, with very large flowers : quite common in gardens.
I. v. var. kermesina. – A glorified form of the type : of a rich wine colour, heavily marked with white at the throat.
I. v. var. pulchella. – A small habited plant, with deep violet-coloured flowers. All are free- growing plants that one can group by the water-side, in the flower border, or plant freely in the wild garden. They produce very beautiful flowers in plenty, but the easy-growing character of the plants has admitted of their being used in the most informal parts of the garden, where they are often compelled to battle with grasses for their living.
There is much to admire in American Irises, and, although some are " weedy," and others difficult to manage successfully, those that are good and easy to cultivate give unlimited pleasure. Of all the Irises it is my pleasure to know, those from America appeal to the artistic sense the most ; they have not the stature of Iris aurea or I. Monnieri, neither have they the huge flowers of I. laevigata, but they have refinement, beauty of form, and artistic colour schemes that equal, if they do not surpass, any other Irises in these respects. George B. Mallett,

For more information on historic Irises visit the Historic Iris Preservation Society at

-- BobPries - 2014-07-22