| Dr. Rodionenko, p. 3550, SIGNA , 2003Iris songarica, the Conqueror of Desertsby Dr. G. Rodionenko - St. Petersburg, RussiaIn every botanical group (section or series) uniting the most closely related species, one can always find a species, whose structure and biology reflect most brightly the way of evolutionary transformation traveled by this group. Among the group of desert irises Ventricosae· (subsection Tenuifoliae) such a species is no doubt Iris songarica. To reveal those characteristics and features in its structure and biology, which enabled it to occupy such a vast area - I consider this to be the goal of this paper.Although this iris is not an ornamental star, information on the peculiarities of this hard-to-domesticate wild grower may be useful to an iridologist of inquisitive mind. All the efforts of both myself and B. Mathew to observe the life of this eremophyte under cultivation have failed. Its rhizomes, if moved in conditions of wet maritime climate, died every time in several weeks. Unfortunately, seed propagation in such a climate has not proved itself either. When working with this species under stationary conditions, I only succeeded in recognizing its features on the earliest stages of development. Seeds germinate gradually, with this process taking place over 5-7 years. To note, the long keeping viability of the seeds is a very useful property under severe desert conditions, as springs, favorable for seed germination and seedling development are quite rare there.In my long-term work with irises, I have paid great attention to their ontogenesis. Unfortunately, stone pages of palaeobotanical memorials are very poor in information on the past of species of the genus Iris. One can read the past of irises successfully enough only if inquisitively studying their individual development, i.e. ontogenesis.The first stage of development is essential in the life of each plant. Most seedlings of bearded and beardless irises on the earliest stage of their life possess a long slender connective, linking a seed with a germ rhizome (Fig. 1, a). There is usually one vascular bundle in the connective, to conduct nutrients from the seed. Species of Spuria Irises have acquired a very short connective in the process of evolution (Fig. 1, b), that provides faster access of nutrients to the young plant, not yet capable of independent life. Externally, seedlings of I. songarica do not differ from those of Spuria Irises, but this is only a formal resemblance. Analysis of the inner structure of I. songarica seedlings allowed me to read a secret of their adaptation to a far greater pace of development, dictated by severe desert conditions. The l. songarica seedlings have six, rather than one, vascular bundles, and the latter can obviously transport water and nutrients, stored in the seed endosperm, six times faster. Moreover, the bundles, threading all the tissue of the cotyledon sheath, give it higher strength in its fight against the fierce elements of desert (Fig. 1, c). I have not found such a construction thus far in any other species of rhizomatous irises.Let us continue a comparative study of structural changes appearing in the process of evolution. Once seedlings have provided themselves with a special structure, increasing their odds in a struggle for existence, what could the most evolutionally labile organ invented be to increase the plant viability? Leaf blades of adult plants of I. songnrica always break off at the same height, and the sheath part of the leaf, persistent at the rhizome, is provided with abundant fiber-bearing vascular bundles. In several years, the bunch base becomes enclosed with a "fur-coat" of dead leaves. It effectively covers the rhizomes and regeneration buds. Despite the southern latitudes where I. songarica occurs, severe winters happen there, and the air temperature often falls below -20 to -25° C. The "fur-coat" is also useful in the late spring and summer. In Uzbekistan, in places where I. songarica has formed enormous irideta (iris communities), precipitation takes place mainly in February, March and a little in April. After April, a hot and dry season begins, when it hardly rains. The sun glares intolerably to heat the soil surface in the noonday hours up to 50-60° C, and the air temperature is as high as 40-45° C and more in the shade. When traveling over those areas in hot days, I often met local men clothed in heat-insulated cotton-lined robes. In this way, they saved themselves from the flaming sun. The "coat" of fiber allows plants of I. songarica to save the stem base from overheat and sunburns in summer months.As a rule, a similar "coat" effectively covers the bases of short-stemmed species of the series Tenuifoliae'''". Moreover, ovaries of their flowers are also buried in the radical "coat". Our character- I. songarica - has chosen another way than I. tenuifolia in the course of evolutional adaptation. It retained rather tall peduncles and made upper sternleaves, so called bracts, suitable for covering the ovaries. I. songarica, I. ventricosa and I. polysticta are record-holders in their bract size among rhizomatous irises. After flowering, such bracts effectively protect tender tissues of the ovaries from dry winds. To emphasize, plants of I. ventricosa have the most perfect construction of the bracts. A Chinese botanist Y. T. Zhao found in bract tissues of this species not only a powerful net of longitudinal veins (vessels), but also the presence of a net of transverse veins. So, these bracts possess the most perfect vascular system, supporting their vitality.In addition, I. songarica also shows high drought-resistance, due to its roots penetrating to deep layers and reaching as deep as 80- 100 min sandy soils.Let us go back to the "coat" of I. songarica; this fiber, in addition to its strength, has antiseptic properties. These features, unfortunately, attracted man's attention. Mass destruction of irideta took place to procure the fiber for brush-making (Fig. 2). The raw material was abundant. The irideta in many regions of the Central Asia extended for tens of kilometers. The total area of growing I. songarica in the late 1950s in Uzbekistan and partly southern Kazakhstan comprised over 700'000 hectares. The thickets of this iris in time of the maximal blossom looked like pastel-blue lakes. This prodigy of nature made an indelible impression on those who had a chance to see it. On the communication of a local botanists, Erezhepov, the fiber was produced in 1950-1960s on a large scale, and the raw procurement led to the total destruction of I. songarica bunches. This barbarous operation has most probably resulted in an uncorrectable damage to the wonderful natural thickets of this iris.ConclusionCertainly, this iris, possessing rare properties, was not created by nature only for the purpose of rope-twining or brush-making. If rationally using its features such: as heat and cold-resistance, capacity for vegetation and flowering under trace amount of precipitation, one will be able by techniques of hybridization and introduction to create in a comparatively short time a new culture of irises capable of successful growing and abundant flowering in southern arid regions of Europe, the United States, areas where every drop of water in summer time is valuable. Such arid regions of our planet as Australia and South Africa, where the cultivation of our favorite irises has been successfully developing in recent years, are also not to be forgotten. To underline, all works, both selection and introduction, with I. songarica should be carried out only in areas with a dry and hot climate, and started only from growing this iris from seed. As to the work on selection, in my opinion, I. polysticha may be of great interest as a partner in this aspect. Its flowers are the only possessors of the yellow color in this group.Ornamental peculiarities of I. songarica can be enriched as well by its hybridization with species and cultivars of Spuria Irises. These irises, although belonging to another subgenus (subgenus Xyridion) are of no doubt genetically close to I. songarica and other species of the subsection Tenuifoliae. The latter is confirmed by both my studies of their ontogenesis and molecular research by T. Hall, N. Tillie and M. W. Chase·.