Primorye Territory (hereinafter referred to as Primorye)  is one of the most interesting and floristically rich areas of Russia and the Russian Far East (RFE). The southern regions of the RFE (Primorye, south of Khabarovsk Territory, southeast of Amur Region. South Sakhalin and the southern Kurile Islands) are situated on the northern extremity of the East Asian floristic region, which encompasses a vast part of East Asia, distinguished by abundance of endemic, preferentially mono- or oligotype seed plant families, and also relict plants preserved in this territory since Tertiary Time. This is the very part of the RFE, where representatives of several families characteristic of subtropical and tropical areas of East Asia occur and are absent in other regions of the Russian Federation. These are representatives of the Polypodiophyta class (the families Daennstaedtiaceae, Plagiogyriaceae, Pleurosoriopsidaceae) and the flowering Magnoliophyta (Actinidiaeae, Cabombaceae, Chlorantaceae, Daphniphyllaceae, Hostaceae, Penthoraceae, Phrymaceae, Pontederiaceae, Schisandraceae, Trapellaceae). These families are represented most abundantly and diversely precisely in Primorye, where only one family (Daphniphyllaceae) is absent. At the same time, two monotypical (characterized by only one species) East Asian families, Pleurosoriopsidaceae and Trapellaceae, are known only in Primorye and are represented by the nemoral-forest fern, Pleurosoriopsis makinoi (Maxim. ex Makino) Fomin, and by the aqueous flowering plant, Trapella sinensis Oliv., respectively.
    Of the six basic subregions of the Russian Far East, Primorye is richest floristically. At present, there is no special floristic report on Primorye, and one can assess the wealth of its flora only approximately by basing on major floristic reports on the entire Russian Far East (Voroshilov, 1966, 1982, 1985; Vascular plants of the Soviet Far East, vols. 1-8, 1985-1996). The overall wealth of the vascular flora of the Russian Far East may be estimated at 4,200-4,500 species from 950-980 genera and 168 families, and that of Primorye at 2,200-2,500 species from 800 genera and 168 families.
    The high level of taxonomic diversity and the basic characteristics of Primorye flora are determined primarily by the position of its territory. Actually, Primorye is at the abutment of two major phytochores of the Holarctic (cold and temperate regions of the Northern Hemisphere), namely the Circumboreal and East Asian floristic regions (Takhtadjan, 1978).
    Uniqueness is imparted to the flora of any territory by endemic species and genera represented by plants growing only in a given area and unknown elsewhere. Of six genera endemic for the Russian Far East, two monotypical genera are represented in Primorye; in respect to Primorye, they are hemiendemic, i.e. also represented in adjacent territories. They are Microbiota decussata Kom, a remarkable coniferous shrub from the Cupressaceae family, which grows on the upper forest extremity exclusively within the bounds of Sikhote Alin mountain range, and Popoviocodonia stenocarpa (Trautv. et Mey.) Fed. From the Campanulaceae family, which is distributed in the southeastern highlands of the Russian Far East.
    According to Voroshilov (1985), precisely Primorye was noted for the highest level of specific endemism and uniqueness of flora among other subregions of the Russian Far East, the respective figures corresponding to 3.4% and 19.5% of 1,720 species of the indigenous element of its flora (without accounting for adventive and naturalized plants). Of the just slightly over 2,000 species cited by Voroshilov (1982) for Primorye, almost 500 do not occur in other subregions of the Russian Far East.
    In the south of the Russian Far East, the flora is distinguished by abundance of relict plants preserved there for historical reasons since the Tertiary Period, since the area virtually had no Pleistocene glaciation (with the exception of several highland sites). Broad-leaved and coniferbroad-leaf (Turgay) forests, widely distributed in Tertiary in Siberia and Russian Far East during Pleistocene cooling, had died off over vast areas t be retained only in the very south of the Russian Far East and adjacent territories of China and North Korea. The largest and most well preserved massif of nemoral (pre-Boreal) forests remained in the basin of Ussuri River in Primorye and Khabarovsk Territories. The abundance of boreal, primarily Okhotsk and Okhotsk-Kamchatka species, is a major feature that helps distinguish the Ussuri taiga from the broad-leaf and mixed Manchurian forests distributed to the south. Here you can simultaneously observe the grape (Vitis amurensis Rupr.) and the cranberry (Oxycoccus palustris Pers.), representatives of the Araliaceae family (Kalopanax septemblobus (Thunb.) Koidz., Eleutherococcus senticosus (Rupr. et Maxim.), E. sessiflorus (Rupr. et Maxim.) S, Y. Hu, Oplopanax elatus (Nakai) Nakai, Aralia mandshurica Rupr. et Maxim.) and the birch species Betula platyphylla Sukacz. or Betula lanata (Regel) V. Vassil., the lotus Nelumbo komarovii Grossh and the sphagnum moss Sphagnum spp. N. M. Przhevalsky, R.K. Maak and V. L. Komarov, the pioneer explorers of Ussuri Region, had already noted with surprise this contrast in the Ussuri taiga and the amazing mixture therein  of various flora elements.
    The southern areas of Primorye and Sikhote Alin abound most in relict plants. According to R. I. Korkishko (1986), 1,413 species, of which 4.4% are Tertiary relict species, grow in Khasan District, the southernmost in Primorye. The following most well-known species may be noted among the rarest and most endangered ones, and those entered in the Red Book of the USSR (1978) and the Red Book of the RSFSR (1988): Nelumbo komarovii, Taxus cuspidata Siebold et Zucc. ex Endl., Oplopanax elatus (Nakai) Nakai, Pueraria lobata (Willd.) Ohwi, Aristolochia manchuriensis Kom., Parthenocissus tricuspidata (Siebold et Zucc.) Planch, Euryale ferox Salisb., Pinus funebris Kom. and others. Like many others, all of them are widespread only in Southern Primorye and are unfamiliar elsewhere in Russia.
    By and large, the southern districts of Primorye are distinguished by highest abundance and specificity of vascular flora compared to other areas of the Russian Far East. Of nearly 500 species known in the Russian Far East only in Primorye, over half were noted only in the south of Primorye. This is primarily due to the direct proximity of this part of  Russia to Northeastern China and North Korea with their rich and largely different flora, the majority of whose representatives penetrate into Southern Primorye, albeit most of them do not occur elsewhere in Russia.

 A. KOZHEVNIKOV, Cand. Sci. (Biology), Head, Department of Botany, Institute of Biology and Soil Science, Russian Academy of Sciences.

Illustrations by Z. Kozhevnikova.