(1916) Teratology in Iris flowers by E. Armitage

Gardeners' Chronicles p. 203, October 28, 1916


IN Irises the flower is regular and the parts are in threes. The petaloid perianth is united below into a tube, and is divided into three outer parts, usually ranging down, the falls, and three inner parts, usually upright, called standards. In the centre of the flower are three united petaloid styles which bend outwards, and beneath these are concealed the three stamens. The seed-vessel, or ovary, is divided into three parts, each containing seeds.

For many years past I have made notes of the occurrence of malformed Iris flowers which have appeared in my collection, and have met with nearly fifty examples in about forty species and varieties, the irregularity being due either to some method of doubling or to the addition or reduction of parts. No doubt many more have been seen by other observers. Out of over two hundred forms in cultivation here, about one fifth have shown themselves to be liable to produce abnormal flowers.

Double Flowers. — The best-known form is that of the Japanese Iris (I. Kaempferi). In the single form of this plant there are three broad hanging falls, three narrow upright standards, three arching styles, and three stamens. I find that in the usual method of doubling the perianth is converted into six broad hanging falls, there being no standards, and besides the three styles and stamens there are also three imperfect, lobed, petaloid stamens. In a double white form I have observed six styles as well as six falls.

In the double Siberian Iris (I. sibirica flore pleno) the doubling is extraordinarily complex, with much irregularity and malformation. From the pedicel (or flower-stalk) arises a primary ovary carrying a whorl of nine standards and falls. From this ovary three more rudimentary ovaries branch out, each bearing about seven standards and falls, within which are a few stamens and small rudimentary style-arms. The whole result, as may be imagined, is a very ugly, misshapen tuft of blue-and-white flowers, several on each stem ; their complexity, perhaps, accounting for their lateness in flowering. A tall variety of I. ochroleuca, var. sulphurea. has produced double flowers with six falls, standards, five styles, and no stamens, some of the inner styles and standards being misshapen.

Another kind of doubling is seen in the occasional fusion of two flowers. Thus in I. variegata Maori King two flowers were fused together, the pedicels, ovaries, and perianth-tubes being connected longitudinally. On dissection, flower No. 1 was found to be normal, with parts in threes; flower No. 2 had four standards, falls, stamens, and styles, and one other central style with no accompanying stamen, the ovary being quinquelocular, with four normal loculi, and one tiny one. containing ovules, between. In I. pallida var. variabilis (a form very liable to flower variation) there was complete fusion of pedicel, ovary and tube, the latter being united along two free edges. When divided along the line of junction each half was found to be alike, containing three normal falls, two normal standards and one half-bladed ; three normal stamens, and three styles, with the edges of the two stylar columns just united. A transverse section of the ovaries showed that the one was trilocular as usual, but in the other the third (outer) loculus was abortive.

In I. aphylla nudicaulis, a curious ease of fusion occurred. The flower contained seven falls, five standards, seven styles and stamens. The ovary was oblong in shape, open in the middle, with seven parietal placentae, each equally provided with ovules, each complete and free, projecting into the cavity. Another double flower occurred in this variety, the parts being all in sixes. It is rather strange that more cases of double flowers should not occur in Irises, where multiplication of parts is so frequent. It is fortunate that it is not so, as we cannot wish for anything to detract from the grace and elegance of the single Iris flowers.

Flowers with Extra Parts.

1. Flowers in Fours. — This is the commonest variation, in which four falls, standards, styles and stamens occur, with no malformations. It has been noted in I. pallida and var. variabilis, germanica type, neglecta Harlequin, amoena Comte de St. Clajr, variegata Rigoletto and Chelles; I. aphylla, I. sibirica, I. vaga, I. reticulata and I. Bakeriana.

2. Flowers Irregular. — Iris pallida, parts in fours, with five stamens, one in the centre of the flower, one of the standards being bearded as well as the falls (this has also been noticed in pallida dalmatica). Pallida variabilis, flower in fives ; pallida Queen of May, several flowers with four falls and styles, otherwise normal, or four falls and standards and five styles. Willie Barr, five falls and standards, four styles and stamens, and a quadrilocuIar ovary; variegata Gracchus, flowers in fives and quinquelocular ovary ; amoena, four falls, otherwise normal. L. Pseudacorus, five falls, three standards, four styles, three stamens, quadrilocular ovary. I. vaga, flowers with four falls, three styles and two or three standards. I. unguicularis (I. stylosa), flowers with four falls, three styles, and two or three standards. I. reticulata, four standards, two falls, three styles and stamens. I. Tauri, three standards and falls, three styles, one branched, four stamens.

3. Flowers Malformed.— I. pallida, a flower with one standard fused all its length with the pedicel, ovary and perianth-tube, the flower assuming a right-angled position to the axis. It had four falls, styles and stamens, and a very small fifth style and stamen, the ovary being quadrilocular ; pallida dalmatica, a flower with bearded standard and an additional rudimentary stamen growing out of the ovary-wall; neglecta Harlequin, six bearded falls and no standards. I. foliosa (I. hexagona var. Lamancei), four falls and stamens, the extra stamen being attached to the extra fall. I. laevigata var. albo-purpurea , three falls and standards, and bunches of abortive stamens on long stylar expansions, with three normal styles in the centre and the usual trilocular ovary. I. Tauri, three falls and styles, four stamens, two standards, and one combined fall and standard. In another flower one of the falls had two crests. I. Vartani alba, four falls and standards, five styles and stamens, three of the latter perfect, "with pollen, the two others abortive and petaloid.

In the bracts which subtend the Iris flowers I have sometimes noticed some strands of green tissue appearing on the otherwise scarious bracts of the pallida group ; but the most marked case of bract-metamorphosis I have studied was in a dark purple specimen of I. xiphioides (the so-called English Iris). The scape bore two flowers. The first one was normal, with normal bracts ; the second flower was also normal, but grew out of a ring of petaloid bracts, which may be described thus : 1st bract, green, sheathing, with a purple petaloid projection on one side two and three-quarter inches long; 2nd, like a small fall, wholly coloured purple, veined, two inches long ; 3rd, similar to the last, but narrower and shorter, one and three-quarters inch long ; 4th, clasping the floral tube, long, narrow, membranous, with slight colour, two and a half inches long.

Seduction of Parts.— This economy of production I have noticed on several occasions. I. pallida Princess Beatrice, three standards and stamens, two falls and styles, and a bilocular ovary. In another flower all the parts in twos except for three standards; pallida variabilis, four bearded falls, two standards, two styles and three stamens, one of the latter exposed, having no style to conceal it. In another flower all the parts were in twos. I. Leichtlinii, two standards, otherwise normal. I. Delavayi, parts in twos and bilocular ovary. I. Xiphium (Spanish Iris), flowers in twos, in blue, orange and yellow; in the last, one of the two standards was bifurcated. Dutch Iris Gerard Dou, flowers in twos. I. xiphioides, flowers in twos, purple and grey.

As a last example in teratology I may instance a flower shown me in a friend's garden, where there was an unusual mixture of colour. The species was the ordinary white I. florentina, and amongst the clumps was one plant which exhibited blotched flowers, white and bluish-purple mixed. One standard was quite blue, two white, and the falls streaked white and blue.

It will be seen from the Iris forms already enumerated that the abnormalities are distributed among the different groups, the bearded (Pogoniris), beardless (Apogon), Juno, Regelia, and so on; not only among garden forms, but true species as well. Neither does the question of excessive or reduced nutrition seem to influence the occurrence, as it may happen or not in species growing side by side, and in either dry or moist habitats. I have not yet observed abnormalities in the numerous forms I grow of Oncocyclus, Korolkowii, and Onco-Regelia. Hybridity cannot encourage it, or it would surely appear among the hybrids of Juno and Onco-Regelia. I suppose, therefore, that it must be a sporting tendency, finding expression in particular individuals. I hope these notes may induce other Iris growers to record their observations on the subject. ---Eleonora Armitage.

Lynch responded later that year.

A.J.Bliss added to these observations in 1917 article

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

-- BobPries - 2014-07-01
Topic revision: r2 - 02 Jul 2014, BobPries
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