Plants of Central Asia - Plant Collection from China and Mongolia, Vol. 8a: Leguminosae PDF

PREFACE

This volume, 8a, of Plants of Central Asia contains the treatment of one of the most important and the largest of the angiosperm families of this region— Leguminosae—with the exception of 2 of its largest and taxonomically particularly complex genera Astragalus and Oxytropis, which will be dealt with in the next volume, 8b. The treatment has been carried out by G.P. Yakovlev who specialised in the study of family Leguminosae. This volume covers 31 genera and 181 species of which 4 have been included provisionally (unnumbered) as these have their presence within the territory not been conclusively established but may be detected in it as they have been reported close to its borders. Inclusion of the Central Asian part of the USSR* territory would add 4 genera and 72 species. Thus, the total number of legumes in the entire Central Asian territory would be 253 species and 35 genera, not counting genera Astragalus and Oxytropis. Of the 31 genera included here, only 3 are quite large—Caragana (41 species), Hedysarum (27 species) and Vicia (19 species). These 3 genera account for almost half of all species treated in this volume.

Without coverage of the 2 largest genera Astragalus and Oxytropis, the phytogeographic review of the family in Central Asian territory would no doubt be incomplete. Nevertheless, some obvious characteristics can be deciphered. Five groups of genera can be distinguished easily on the basis of their genesis: endemic, East Asian, Himalayan, boreal and Fore Asian- Eastern Mediterranean. Only Ammopiptanthus with 2 species having narrow distribution ranges in western (A. nanus) and eastern (A. mongolicus) Central Asian desert regions is the lone truly endemic genus. This very ancient genus of legumes from the primitive tribe Thermopsideae has evidently descended from the period when rhinoceros and ostrich grazed the savanna expanses of Central Asia and the elements of its flora shared much in common with those of Africa.

Sphaerophysa too should evidently be regarded as an analogous Central Asian genus although its distribution range extends somewhat beyond the boundaries of this region into the adjoining Middle Asia, Dauria and loessial plateau of China.

Taxa of warm-temperate East Asia origin are represented by genera Sophora, Thermopsis (main section), Lespedeza, Kummerowia, Gueldenstaedtia and Caragana. Most of these are found only in Central Asia or have stray derivatives but ancient genus Thermopsis has produced here some derivatives (Th. mongolica, Th. przewalskii, Th. smithiana, Th. turkestanica) and reached Middle Asia. Caragana has found in Central Asia, so to say, a second home and formed there secondary centres of modification with entire series of local species (more than 20 in all: C. acanthophylla, C. alpina, C. arcuata, C. aurantiaca, C. bongardiam, C. brachypoda, C. bungei, C. chinghaiensis, C. dasyphylla, C. gobica, C. junatovii, C. kirghisorum, C. korshinskii, C. leucophloea, C. leucospina, C. polourensis, C. pruinosa, C. soongorica, C. tangutica, C. tibetica, C. tragacanthoides).

Monotypic genus Stracheya with Himalayan species S. tibetica and a new genus Spongiocarpella originated from the Himalayas. The latter is represented by 4 species in Central Asia: Himalayan-southem Tibetan S. nubigena, southern Tibetan S. spinosa, eastern Gobi S. grubovii and Kashgar S. potaninii. All of these are acanthopulvinates.

The group of boreal genera should include Lathyrus, Vicia, Melilotus, Melilotoides and Trifolium. These are largely associated with the forest belt of mountains, predominantly in the northern part of the region and represent recent migrants. They either did not develop endemic species at all (Lathyrus, Melilotus, Trifolium) here or gave rise to neoendemics like Pamir Melilotoides pamirica and southern Tibetan M.tibetica, Tibeto-Himalayan Vicia tibetica and the widely distributed steppe species V. costata.

The most abundant group of genera naturally confined mainly to the western half of Central Asia, specially to Sinkiang, covers eastern Mediterranean- Fore Asian genera Ammodendron, Alhagi, Calophaca, Chesneya, Cicer, Eremosparton, Eversmannia, Glycyrrhiza, Halimodendron, Hedysarum, Lotus, Medicago, Onobrychis, Ononis, Trigonella. Most of these have only derived from Middle Asia but some have formed local endemic species. These are: Medicago (Junggar-Tien ShanM. agropyretorum, M. schischkinii and M. tianschanica, Alashan M. alaschanica, Fore Balkhash M. trautvetteri), Chesneya (Ch. dshungarica, Khesi Ch. gansuensis, western Gobi Ch. grubovii and Mongolian Ch. mongolica\ Calophaca (funggar C. chinensis and C. soongorica), Glycyrrhiza (Gobi-Kashgar G. inflata). Particularly adpated here is genus Hedysarum giving rise to a whole series of local species (H. iliense, H. kirghisorum, H. krylovii, H. multijugum, H. petrovii, H. przewalskii, H. scoparium, H. semenovii, H. songoricum, H. splendens)

Legumes occupy a prominent position in the plant cover of Central Asia as coenosis- and landscape-forming plants. This is primarily true of pea shrubs. Shrubby steppes formed on plains cover much of the expanse. These are: Caragana microphylla predominantly on sandy soil in eastern Mongolia, C. pygmaea in the zone of arid sandy steppes in the south and C. stenophylla in the zone of desert steppes. C. leucophloea associations form in western Mongolia and Sinkiang on desert rubbly-rocky mountain trails and on sand in plains while extremely xerophilic C. brachypoda is found in the deserts of Eastern Gobi. Thickets of C. bungei and C. spinosa are widespread in the mountain valleys of Western Mongolia, while C. jubata and C. roborovskyi are found along mountain slopes of Tien Shan.

Salt tree Halimodendron halodendron forms large thickets on solonetzic soil along valley floors, in tugais and gorges of brooks in Sinkiang. Camel's-thom Alhagi associations occupy considerable expanses in deserts and semi-deserts of Sinkiang.

Associations of shrubby sweet vetch Hedysarum fruticosum with very beautiful colouration are common on shifting sand in Mongolia and thickets of endemic Ammopiptanthus mongolicus in Alashan Gobi. Associations of licorice—Glycyrrhiza uralensis, G. glabra, G. inflata—occupy large areas on solonetzic sandy soils in Mongolia as well as Sinkiang, specially in oases.

It must be emphasised that many legumes represent important pasture crops—pea shrub (Caragana microphylla, C. leucophloea, C. pygmaea, C. aurantiaca and many others) and camel's-thom as fodder for camels, clover, sweet clover, medic, vetch as valuable constituent of steppe and meadow pastures for large and small cattle. Several legumes form essential medicinal and commercial crops, like licorice, thermopsis and sophora.

In this volume, O.I. Starikova translated the Chinese texts on herbarium labels and Chinese floristic literature.

Artist O.V. Zaitseva prepared the plates of plant drawings. I.B. Tikhmeneva prepared the maps of distribution ranges and indexes

Author: V I Grubov