Proceedings of the Royal Society of Edinburgh, 89B, 135-146, 1986 Notes on the distribution, climate and flora of the sand deserts of Iran and Afghanistan H. Freitag Arbeitsgruppe Morphologie und Systemarik der Pflanzen, Universitat Kassel, Heinrich-Plett-Strasse 40, D-3500 Kassel, B.R.D. Synopsis An account is given of the distribution of the sand deserts in Iran, Afghanistan and Pakistan Baluchistan, where they cover large surfaces on the plains at low and medium altitudes. Climatologically they differ considerably from each other with respect to winter temperatures, but the latitudinal sequence is obscured by elevation effects. About one half to one third of the species are strict psammophytes; structurally they are the most important components of the different plant communities and in mobile sands usually no other plants occur. Their phytogeographical and taxonomic relationships are discussed in detail and attempts made to relate the distributional patterns to certain ecological factors. 66% of the species are truly Irano-Turanian, 23% are endemics, mostly derivatives of Irano-Turanian species, 10% are SaharoArabian and 7% are biregionals. Further aspects pointed out are the representations of life forms of families and genera. The results in the deserts studied give support to the concept of a coherent IranoTuranianfloristicregion. The southern deserts form a sub-unit of their own, characterised by high numbers of endemics, some intruding Saharo-Arabian species and an absence of several otherwise common IranoTuranian species. Introduction Up till now, information about the ecology, flora, and vegetation of the sand deserts in Iran and Afghanistan has been very scanty, as can be judged from the small entries in the voluminous work of Zohary (1973). Even the remarkable progress of Flora Iranica (Rechinger 1963-) has not altered the situation very much, as it includes only few data about the ecology of species dealt with. Evidently, detailed studies on the ecology of species and particularly on plant communities can only be carried out after the taxonomic base has been laid down. The flora of the sand deserts is comparatively poor in species, but it includes many critical species, especially in the genera Salsola, Calligonum and Astragalus sect. Ammodendron, which are not yet dealt with in Flora Iranica, or are still under dispute, as Calligonum. Besides, every thorough field campaign yields species new to the Flora Iranica region or even species new to science. The provisional account presented here is based on the author's own experience from field work carried out during several years in all seasons, and on careful evaluation of the pertinent literature. Whereas almost all sand deserts of Afghanistan have been seen and studied between 1966 and 1970, the coverage of Iran is highly incomplete, being limited to the sand areas in northern Central Iran in the provinces Tehran, Semnan and W Khorasan, which were visited in 1976 and 1978. More detailed floristic data are available only from certain sand deserts in the Kavir National Park (Rechinger & Wendelbo 1976), the Touran Protected Area (Rechinger 136 H. Freitag 1977) and—most important as examples of the southern type—from the Dasht-e-Lut and the Jaz Murian depression (Leonard 1981-85). It must be emphasised that the flora of most remaining Iranian sand deserts is very fragmentarily known; this is particularly true for the southernmost ones in Khuzestan. During the preparation of this paper, it proved very useful to have had personal taxonomic experience in several of the difficult groups, particularly the Chenopodiaceae. Distribution and climatological conditions Sandy habitats are widely distributed in the semideserts of Iran and Afghanistan. This paper, however, deals only with the most extensive and typical kind of sandy habitat, the real sand deserts or "sand seas". The very common local sand accumulations along most dry river beds and the shallow sand sheets covering many plains are excluded; they are also inhabited by some widespread psammophilous plants, but usually dominated by species of disturbed habitats or species of the plains. The only important exception known to the author, the Dasht-e-Nawor, is discussed later in this paper. The sand seas consist of vast dunefields,with sands reaching a thickness of from a few metres up to more than 100 metres. The surface is more or less mobile or stabilised, depending upon the degree of aridity and anthropogenic influence. Even in the remotest and most inaccessible parts, at least the dune crests are built of more or less mobile sands. The dune structure is more or less irregular, caused by winds blowing from different directions. More typical longitudinal dunes and barchans occur only peripherally, where the former type seems to be related to the occurrence of some taller (shrubby) dune vegetation, and the latter is usually completely devoid of vegetation and may move several metres per year. Some authors (e.g. Bhimaya, cited in Ehlers 1980) ascribe the formation of the sand seas to long-lasting desertification processes, but there is only evidence for re-mobilisation of already more densely vegetated dune fields with subsequent marginal expansion and rather small-scale formation of new dunes by sands outblown from degraded gravelly plains. In fact, the existing sand seas are either more or less active and continuing to grow in accordance with the actual climate (that seems to be true for S Afghanistan and S Iran), or they have originated during drier periods of the past and today they tend to be stabilised by dense psammophytic vegetation. In either case they are the result of weathering, transportation by water and accumulation by wind during many millenia. Figure 1 gives the distribution of the sand deserts in a highly generalised manner because of the irregular surface and the mosaic-like character of many individual areas. Another delimitation problem occurs at the southern border of the sand desert in NW Afghanistan as in adjacent Turkmenian Badghys, where the sand accumulations grade continuously into the likewise aeolic loess accumulations. The distribution of sand deserts in Iran and Afghanistan is widely determined by topography, amount of precipitation and direction of the prevailing winds. They are located in areas with less than 200 mm annual mean precipitation and most of them receive less than 150 mm. The only exceptions are the sands in Khuzestan (S Iran), where precipitation may reach 250 mm (as in some marginal parts of the Indian desert). The The sand deserts of Iran and Afghanistan 137 spectacular regeneration of vegetation and sand fixation after initial mulching with crude petrol from the Khuzestan oil fields clearly indicates less arid climatic conditions, which are probably marginal for the formation of sand deserts. (It should be noted that the course of the 200 mm isohyete in Figure 1 is not based on the Climatic Atlas of Iran (1965), which gives very generalised and certainly too low values for S Iran, but rather the map of Bobek (1952), which agrees much better with the vegetation of the respective areas and the few available measurements.) From Figure 1 it is evident that in Iran the sand deserts, except the sands of Khuzestan and the depression of Jaz Murian, are confined to the central plateau. Situated at altitudes of about 500-1200 m, they cover a surface of about 183,000 km2 (11% of Iran) with a percentage of c.34% in Esfahan and c.16% in Khorasan and Kerman provinces (Bhimaya 1971, cited in Ehlers 1980). In contrast, their distribution in Afghanistan is peripheral. In N Afghanistan the southeastern corner of the Turkmenian Kara Kum extends along the lowlands of the Amu-Darya at 300-400 m altitude from Faryab to Kunduz provinces. In S Afghanistan the largest sand deserts are located in Kandahar and Helmand provinces ("Registan") and in Chakhansoor at altitudes of 500-1000 m, and from there they continue into Pakistani Baluchistan. The absence of larger sand deserts from the likewise arid W Afghanistan is probably related to the strong northern or northwestern 'wind of the 120 days', which carries its heavy sand load further the S and SE. A comparison of the diagrams on both sides of Figure 1 reveals that climatic Figure 1. Distribution of sand deserts in Iran and Afghanistan, as related to the 200 mm isohyete, and climate diagrams of selected stations (taken from Walter & Lieth 1960); data from various sources, modified. 138 H. Freitag conditions seem to be rather uniform all over the area. There are no significant differences over long distances both in W-E and N-S directions, as may be seen from the diagrams of Kisil Arvat in Turkmenia, Termez on the banks of the Amu-Darya, and Esfahan in western C Iran. However, on closer inspection a quite steep but discontinuous gradient in winter temperatures, exemplified by the absolute minima and consequently also in the annual mean temperatures, becomes detectable: Nukuss just S of Lake Aral ( - 2 6 0 ; 10-8), Esfahan (-200; 15-5), Chaman (-11-7; 18-8), Seistan (-8-3; 20-6) and Chabahar ( + 7-2; 25-7). Despite almost equally hot and dry summers, it must be expected that differences in frost resistance lead to floristic differentiation, which indeed is very pronounced between N Afghanistan and N and C Iran on one hand and S Iran, S Afghanistan and Pakistani Baluchistan on the other. The striking uniformity of climate and subsequently of the flora from central Iran northwards up to the Kara Kum is mainly due to the fact that the normal temperature gradient does not become effective because of the higher elevation of the more southern semideserts. The psammophytic flora General remarks As everywhere in sandy habitats, plant species growing in the sand deserts of Iran and Afghanistan are highly adapted to their special environment. The particular stresses are burial by sand, desiccation by outblown roots, dying off of seedlings by rapid exsiccation of the upper soil layer or by extremely high temperatures, etc. Much less known are the advantages of comparatively high amounts of water stored in the subsoil and the absence of higher salt contents. It is not surprising that most species are highly specialised as psammophytes. The plant communities on mobile sands are made up of only a very small number of extreme psammophytes. The more the sands become stabilised, the more psammophytic species invade. Under natural conditions without strong human pressure, they form open shrublands, surpassing the vegetation of most adjacent non-sandy habitats in their height, coverage and productivity. Beside the true psammophytes, a growing number of more ubiquitous species occur, but they remain subordinate. The only exceptions are the very few cases of old fossil dunes with a completely stabilised surface and an advanced formation of a soil profile usually indicated by the development of a gypsum horizon. In Tables 1, 2a and 2b a first comprehensive list of the psammophytic flora of the sand deserts of the Flora Iranica region is presented. It is based on repeated screening of hundreds of vegetation inventories and other field notes, and on an additional evaluation of the literature. Thefirstdraft, shown and discussed at the time of the symposium, has been further improved by taking into consideration some comments kindly given by Professor K. H. Rechinger. Nevertheless, the enumeration should be considered as a first approach. Further studies, particularly in central and S Iran, and in Pakistani Baluchistan may add more species or may lead to re-evaluations. For considering a species as a genuine psammophyte, the strongest criteria have been used. Here only a species strictly bound to sandy habitats all over its distributional area is included. I am quite aware of the subjective component of using that narrow The sand deserts of Iran and Afghanistan 139 concept because, besides the obligate psammophytes listed below, there are others with a preference for sand deserts, but which also occur on quite different habitats: Dendrostellera lessertii, Haplophyllum robustum, Schumannia karelinii, Salsola leptoclada and Euphorbia turcomanica. Quite a number of annuals are almost equally common on stabilised sands, on loess soils and on sandy-gravelly alluvial soils of the plains. Finally the lists have been re-checked against the tables of several Soviet authors who dealt with the Turkmenian sand deserts, in particular Nechajeva et al. (1973) and Korovin (1961). Distributional types in the psammophytic flora Despite the discontinuous distribution of the sand deserts, most psammophytes evidently were and probably still are able to reach even the most remote sand fields. Except for a few species (e.g. of Euphorbia, Chrozophora and Allium), their diaspores are equipped with very effective anemochorous devices (wings, feathery appendices, balloon-like vesicles, etc.) and the frequent and strong winds can carry them over long distances. That makes psammophytes particularly suitable for phytogeographical considerations, because their respective areas are generally more strictly controlled by actual climatic factors than in many other species. Nevertheless, other ecological factors as competition with other species (particularly of the same life form) and history (age of the taxon and possibility of migrations during past periods with different climates) are likewise effective. A very first but inevitably fragmentary attempt to detect distributional pattern in the psammophytes of Iran was undertaken by Hedge & Wendelbo (1978). Widespread species (Table 1) A remarkable high number of psammophytes are spread all over the sand deserts of Iran, Afghanistan and adjacent areas. Species of all life forms belong here, but annuals are more numerous. Evidently those species do not respond to the considerable variation of temperature conditions within the area under concern. Most of them do not extend further S or SW but are widespread in Soviet Middle Asia (Srednaya Aziya). They are mostly representative of the Irano-Turanian floristic element. A much smaller group of species likewise extends far beyond the frontiers of Iran and Afghanistan in both directions to the N and S. The area of these biregional IranoTuranian/Saharo-Arabian species includes at least large parts of Arabia as the eastern sector of the Saharo-Arabian floristic region. Most individual species have their centre of distribution either in the Irano-Turanian (e.g. Haloxylon persicum) or the Saharo-Arabian region (e.g. Centropodia forsskalii). Species with more restricted areas of distribution (Table 2a, b) All psammophytes with distributional lines inside the area are listed in Table 2a, b, together with their occurrences in the 5 geographical subunits: NW Afghanistan, N and central Iran, S Iran, S Afghanistan, Pakistani Baluchistan, and central Afghanistan. The first group comprises again Irano-Turanian species, which in contrast to those 140 H. Freitag Table 1. Widespread psammophytic species (mostly Irano-Turanian elements; a few biregional Irano-Turanian and Sahara-Arabian elements are marked with +) Shrubs, dwarf shrubs Ammodendron conollyi Bunge (only Turkmenia and Iranian Baluchistan) Calligpnum caput-medusae Schrenk C. leucocladum (Schrenk) Bunge s.l. (incl. var. serratum Litv. & C. persicum Boiss.) C. rubens Mattel C. setosum Litv. Convolvulus erinaceus Ledeb. C. korolkovii Regel & Schmalh. Ephedra strobilacea Bunge + Haloxylon persicum Bunge ex Boiss. & Buhse Salsola richteri Kar. ex Litv. Other perennials Astragalus (Eremophysd) chivensis Bunge + Centropodia forsskalii (Vahl) Cope ( = Asthenatherum forsskalii) Cistanche ambigua (Bunge) G. Beck C.flava (C. A. Mey.) Korsh. Haplophyllum bungei Trautv. Heliotropium arguzioides Kar. & Kir. H. micranthos (Pall.) Bunge (only Turkmenia and S Iran) Stipagrostis pennata (Trin.) de Winter Geophytes (ephemeroids) Allium borszczowii Regel A. fibrosum Regel Carex physodes M. Bieb. Ferula foetida (Bunge) Regel Iris falcifolia Bunge Annuals (and biennials) Agriophyllum latifolium Fischer & C. A. Mey. A. minus Fischer & C. A. Mey. Astragalus (Oxyglottis) ammophilus Kar. & Kir. * A. (Harpilobus) hauarensis Boiss. Centaurea pulchella Ledeb. ( = Hyalea pulchella (Ledeb.) C. Koch) Chrozophora gracilis Fischer & C. A. Mey. + C. hierosolymitana Spreng. Cousinia bipinnata Boiss, s.l. (incl. C. oxiana Tschern. & C. turkmenorum Bornm.) *Cutandia memphitica (Spreng.) Benth. Euphorbia cheirolepis Fischer & C. A. Mey. ex Ledeb. E. densa Schrenk E. turczaninowii Kar. & Kir. Horaninovia anomala (C. A. Mey.) Moq. H. ulicina Fischer & C. A. Mey. Kochia iranica (Bornm. & Hausskn.) Litv. K. odontoptera Schrenk Lappula semiglabra (Ledeb.) Guerke Octoceras lehmannianum Bunge Oligochaeta minima (Boiss.) Briq. Salsola implicata Botsch. S. praecox Litv. *Schismus barbatus (L.) Thell. + Silene arabica Boiss. S. nana Kar. & Kir. Spirorhynchus sabulosus Kar. & Kir. Tetracme recurvata Bunge 141 The sand deserts of Iran and Afghanistan Table 2a. Psammophytic species with more restricted distribution NW Afgh. N&C Iran S Iran S Afgh. &Bal. C Afgh IRANO-TURANIAN species Shrubs, dwarf shrubs Astragalus (Ammodendron) nigricans Barneby Polygonum arianum Grig. Acanthophyllum elatius Bunge Ammothamnus lehmannii Bunge Artemisia diffusa Kraschen. Mausolea eriocarpa (Bunge) Poljak. ex Podl. Calligonum microcarpum Borszcz. Smirnowia turkestana Bunge Zygophyllum eichwaldii C. A. Mey. in Eichw. + + + + + 7 + + + + + + + + 7 + Other perennials Jurinea derderioides C. Winkl. Stipagrostis karelinii (Trin. & Rupr.) Tzvelev Astragalus (Myobroma) flexus Fischer Eremostachys regeliana Aitch. & Hemsl. Heliotropium acutiflorum Kar. & Kir. H. chorassanicum Bunge H. transoxanum Bunge + + + + + + + + + + + + + Geophytes (ephemeroids) Allium caspium (Pall.) M. Bieb. A. sabulosum Stev. ex Bunge Dorema sabulosum Litv. Eminium lehmannii (Bunge) O. Kuntze Merendera robusta Bunge + ? + + + + + + + + + + + + + ? + + ? + + + + Annuals Cousinia orlhacantha Tscherneva Chamaesphacos ilicifolius Schrenk Cithareloma lehmannii Bunge Consolida camptocarpa (Fischer & C. A. Mey.) Nevski Corispermum lehmannianum Bunge Euphorbia inderiensis Less, ex Kar. & Kir. Launaea korovinii (Popov) Popov ex Pavlov (+ ) (+) cited in Table 1 fade out in central Iran and are absent from S Iran, S Afghanistan and Baluchistan. Stipagrostis karelinii (not yet mentioned in Flora Iranica) in Figure 2 serves as an example. The reasons for the absence from the southern sand deserts are difficult to explain. Some species seem to have problems coping with the harsher environmental conditions, particularly with regard to their water balance or the establishment of seedlings because of the higher temperatures during the shorter rainy season and the less predictable rainfall. That could well explain the distribution of the geophytes and many annuals. Other species are represented in the southern part of the area by closely related vicariants (cited in Table 2b under endemics), which probably evolved in periods of more pronounced isolation and may have developed more effective adaptations to the southern environments. Such pairs of vicariant species are Calligonum microcarpum and C. amoenum, Cithareloma lehmannii and C. registanicum, Eremostacys regeliana and E. ammophila, Ephedra strobilacea and E. 142 H. Freitag Table 2b. Psammophytic species with more restricted distribution NW Afgh. SAHARO-ARABIAN species N&C Iran S Iran S Afgh. &Bal. c Afgh. Shrubs Calligonum crinitum Boiss. Other perennials Cyperus conglomerates Rottb. Pennisetum divisum (Gmel.) Henrard Annuals Eremobium aegyptiacum (Spreng.) Schweinf. & Aschers. Ifloga spicata (Forsskal) Schultz-Bip. Launaea capitata (Spreng.) Dandy Neurada procumbens L. Savignya parviflora (Del.) Webb Tribulus longipetalus Viv. T. ochroleucus (Maire) Ozenda & Quezel ENDEMIC species Shrubs, dwarf shrubs Astragalus (Ammodendrori) kavirensis Freitag A. (Ammodendrori) aff. ahmed-adlii A. (Ammodendrori) oligophyllus Boiss. Calligonum amoenum Rech. f. & Schim.-Czeika C. laristanicum Rech. f. & Schim.-Czeika Ephedra microbracteata Ghahreman Noaea griffithii Bunge Astragalus (Ammodendron) aff. oligophyllus Astragalus (Aegacantha) antheliophorus Demi Other perennials Heliolropium rudbaricum (Bornm.) Riedl Aeluropus macrostachys Hack. Astragalus (Eremophysa) registanicus Rech. f. Eremostachys ammophila Rech. f. Cousinia ammophila Rech. f. Fibigia compacta Rech. f. Piptatherum rechingeri (Bor) Freitag Annuals Cithareloma registanicum Rech. f. Fagonia ovalifolia Hadidi Heliotropium remotiflorum Rech. f. & Riedl Arnebia latebracteata Riedl Lappula leonardii Riedl Launaea platyphylla Rech. f. Psammogeton spec. nov. microbracteata. In the area under review, most Irano-Turanian species of Table 2a agree to their distribution patterns, but one group of specimens seems to be confined to the sand deserts N of the mountain divide formed by the Hindukush-ParopamisusKopet Dagh system, and probably they never managed to cross it. Most characteristic examples of this group, which represents the Turanian sub-element, are Polygonum arianum (not recorded from Afghanistan before), Jurinea derderioides and The sand deserts of Iran and Afghanistan Figure 2. 143 Distribution of: Stipagrostis karelinii, an example of an Irano-Turanian species with a restricted distribution absent from all southern deserts; and Pennisetum divisum, an example of an widespread Saharo-Arabian species, extending into the southern deserts. Cousinia orthacantha. Other species, so far only known from the Turkmenian sands, may be found in the sand deserts at the Amu-Darya in NW Afghanistan, where botanical field work was, and still is, almost impossible for political reasons. Most probable candidates to be found there are Acanthophyllum korolkovii, Ammodendron eichwaldii, several Astragalus species of the sections Ammodendron {A. badghysi, A. excedens, A. unifoliatus) and Spryginiana (A. petunnikovii), Cousinia alata and C. psammophila, Cryptodiscus ammophilus, Eremosparton aphyllum and E. flaccidum, Ferula litwinowiana, Lipskyella annua, Salsola paletzkiana and Tournefortia sogdiana. A second group is formed by Saharo-Arabian species (Table 2b), which occur only in the southern sand deserts. They are less numerous, but a few of them are important components of the respective plant communities, particularly Pennisetum divisum (Fig. 2) and Cyperus conglomeratus. However, they are always outnumbered by Irano-Turanian and endemic species, but admittedly the southernmost sand deserts in Khuzestan, in the Jaz Murian depression and in Pakistani Baluchistan have not yet been studied phytosociologically. No doubt, the more or less identical northern borderline of the Saharo-Arabian species is determined directly or indirectly by low winter temperatures. Other environmental factors are almost alike and all species have the ability of long-range dispersal. The third group is made up of endemic species. The 21 species (including 3 species not yet described) are very unevenly distributed. NW Afghanistan has none, and the bulk of the endemics are concentrated in the southern sand deserts. N and central Iran and S Afghanistan have 2 endemic species in common {Astragalus oligophyllus and Heliotropium rudbaricum). Both belong to very critical groups and their distribution is incompletely known, so they might be found in other parts of the area. Taxonomically they are likewise closely allied to Irano-Turanian psammophytes. The southern sand deserts have quite a number of endemics in common, but each area has its own 144 H. Freitag set of narrow endemics. Most of the southern endemics are again offsprings from Irano-Turanian psammophytes or at least psammophilous species. It is interesting that a few endemics have without doubt originated from Saharo-Arabian stock, in particular Fagonia ovalifolia, Launaea platyphylla and probably the more isolated Aeluropus macrostachys. A very peculiar case is Noaea griffithii Bunge. It may be a remnant of an old indigenous subtropical element comparable to Stocksia brahuica which has a very similar distribution, albeit it grows along dry river beds. The most remarkable and unusual case of local endemism in psammophytes is displayed by the group Cousinia ammophila, Fibigia compacta, Astragalus (Aegacantha) antheliophorus and Piptatherum rechingeri. These 4 species are confined to the rather small and shallow sand fields in the Dasht-e-Nawor depression in eastern central Afghanistan. The sands cover less than 1 km2 at an altitude of c.3000 m and are surrounded by high mountain ranges. The absence of even widespread and otherwise common psammophytes and the evolution of that number of endemics can only be understood in terms of highly effective and long-lasting topographical and ecological isolation. In striking contrast to all the other endemic psammophytes, these species did not evolve from progenitors already adapted to sandy habitats, but from species of the lower alpine slope vegetation, with Cousinia multiloba, Fibigia membranacea, Astragalus (Aegacantha) spec, and Piptatherum laterale on adjacent slopes being respectively the closest relatives. Concluding remarks According to present-day knowledge, the number of true psammophytes in the sand deserts of Iran and Afghanistan amounts to 106 species. They make up approximately one half to one third of the total number of species to be found in these habitats. With regard to distributional patterns (see Table 3), the overwhelming majority of species (62%) belong to the Irano-Turanian element. This is followed by a remarkably high percentage of endemics (22%) and a much smaller number of Saharo-Arabian (9%) and biregional species (7%). The tabulation demonstrates the Irano-Turanian character of the flora in the Iranian and Afghan lowlands and plateaux, where almost all sand deserts are located. Their floristic separation from the Transcaspian lowlands, the Turanian subregion, is much weaker than might be expected. Very pronounced is the differentiation into a northern sector including N and central Iran and N Afghanistan, and a southern sector with significant intrusions of Saharo-Arabian species. More precise conclusions for the southern deserts must Table 3. Distributional types and life forms in the psammophytes of Iran and Afghanistan Distributional type Irano-Turanian Ir.-Tur. & Saharo-Arabian Saharo-Arabian Endemics Total Shrubs, dwarf shrubs Other perennials Geophytes Annuals, biennials 18 1 1 9 14 1 2 7 6 — — — 28 5 7 7 29 = 27% 24 = 23% 6 = 6% 47 = 44% Total s. % 66 7 10 23 62 7 9 22 106=100% 145 The sand deserts of Iran and Afghanistan await careful phytosocjological studies in southern Iran and in Baluchistan. The percentage of the endemics is somewhat smaller than in most other habitat types. The reason is seen in the anemochorous distribution of the species and their high degree of adaptation to the special habitat. More than 80% of the endemics are restricted to the southern deserts and, together with the occurrence of Saharo-Arabian plants and the rather sudden thinning-out of some Irano-Turanian species, they underline the distinct phytogeographical position of that southernmost part of the Irano-Turanian region. However, it should be noted that the endemics, except for a very few species of Saharo-Arabian or unknown origin, have originated from truly Irano-Turanian progenitors, usually of a psammophytic character. That is also reflected in Table 4 by the list of genera with higher numbers of endemics. With respect to life forms (Table 3) it is noteworthy, but not surprising, that the annuals (including biennials) dominate with almost one half of the species total, followed by shrubs and dwarf shrubs with about one third and other perennials with c. one quarter. Geophytes are poorly represented and occur only in the IranoTuranian group. The family representation (Table 5) shows a predominance of the Fabaceae, Asteraceae, Chenopodiaceae, Boraginaceae, Polygonaceae and Poaceae both in species numbers and in structurally important components of the plant communities. Fabaceae and Polygonaceae are each represented by 9 species of shrubs and dwarf shrubs. They usually determine the shape and aspect of the respective associations. Table 4. Genera with higher numbers of endemic psammophytes Number of species 11 (5) 8 7 4 4 3 Genus Astragalus (sect. Ammodendron) Calligonum Heliotropium Salsola AIHum Cousinia Table 5. Family representation in the psammophytes of Iran and Afghanistan Family Fabaceae Asteraceae Chenopodiaceae Boraginaceae Polygonaceae Poaceae Brassicaceae Euphorbiaceae Zygophyllaceae Alliaceae Caryophyllaceae Lamiaceae Apiaceae Other families Shrubs, dwarf shrubs Other perennials Geophytes Annuals, biennials 9 2 3 — 9 — 1 — 1 — 1 — — 3 3 2 — 6 — 6 — — — — — 2 — 5 — — — — — — — — — 4 — 2 9 9 4 — 2 7 6 3 — 2 1 1 1 2 Tot 14 13 12 10 9 8 8 6 4 4 3 3 3 9 146 H. Freitag Boraginaceae and Poaceae have the highest number (6 species) of hemicryptophy tes, which contribute significantly to the biomass of the plant communities and play a most important part in sand fixation (Heliotropium, Stipagrostis). Asteraceae and Chenopodiaceae have the highest number (9 species) of annual psammophytes, besides some representatives of other life forms. References Bobek, H. 1952. Beitrage zur klima-okologischen Gliederung Irans. Erdkunde 6, 65-84. Climatic Atlas of Iran 1965. Tehran: University Press. Ehlers, E. 1980. Iran. Grundzuge einer geographischen Landeskunde. Darmstadt: Wissenschaftliche Buchgesellschaft. Hedge, I. C. & Wendelbo, P. 1978. Patterns of distribution and endemism in Iran. Notes from the Royal Botanic Garden Edinburgh 36, 441—464. Korovin, E. P. 1961. Rastitel 'nost' Srednej Azii i Juzhnogo Kazakhstana. Vol. 1 Tashkent: Izd. Akademii Nauk Uzbekskoj SSR. Leonard, J. 1981-1985. Contribution a I'etude de la flore et de la vegetation des deserts d'Iran. 5 Fasc. Bruxelles: Jardin botanique national de Belgique. Nechajeva, N. T., Vasilevskaja, V. K. & Antonova, K. G. 1973. Zhiznennyje formy rasteij pustyni Karakumy. Moscow: Nauka. Rechinger, K. H., ed. 1963-. Flora Iranica. Flora des Iranischen Hochlandes und der umrahmenden Gebirge. Graz: Akademische Druck und Verlagsanstalt. 1977. Plants of the Touran Protected Area, Iran. Iranian Journal of Botany 1, 155-180. & Wendelbo, P. 1976. Plants of the Kavir Protected Region, Iran. Iranian Journal of Botany 1, 23-56. Walter, H. & Lieth, H. 1960-67. Klimadiagramm-Weltatlas. Jena: G. Fischer. Zohary, M. 1973. Geobotanical foundations of the Middle East. 2 Vols. Stuttgart/Amsterdam: G. Fischer/ Swets & Zeitlinger.