Botany - B.E. Yakubenko 2017

Part Three. Plant Kingdom (Planthae)
Chapter XI. Fundamentals of Phytogeography
11.4. Floristic Kingdoms of the Earth

The floristic diversity of our planet is driven by METABOLISM/18.html">The Influence of physiographic factors across individual regions. Each region possesses a specific flora comprising characteristic families, genera, species, and infraspecific taxa that are absent in other areas and grow there in limited numbers.

According to A. Takhtajan (1974), the modern flora of the globe is divided into the following floristic kingdoms: Holarctic, Paleotropical, Neotropical, Cape, Australian, and Holantarctic (Fig. 114). Floristic kingdoms are distinguished based on familial and high-rank generic endemism; floristic provinces by the presence of endemic genera and significantly high species endemism; floristic provinces by species endemism; and districts by subspecies and poorly defined species endemism.

The Holarctic Kingdom spans vast expanses of North America, Europe, Asia, Africa, and PARTS OF THE Middle East. The flora of this kingdom shares a common origin and numerous similarities across various geographically isolated regions and areas. The primary feature uniting them is the presence of about 40 endemic families, 20 of which belong to the subtropics of Asia, Africa, and the Near and Middle East. The principal ones include Ginkgoaceae, Lauraceae, Platanaceae, Trochodendraceae, Aphyllanthaceae, and Pterostemonaceae.

The Mediterranean Kingdom encompasses a series of floristic regions. The Mediterranean region covers southern Europe, parts of northern Africa, and the Near and Middle East. The formation of its flora is shaped by the Mediterranean climate. Its arid nature has led to the dominance of xerophytes in the vegetative cover, which are characteristic of this area. Its flora features 50 endemic species, including sweet bay, stone pine, common myrtle, strawberry tree, pistachio, and others. There are also quite a few generic endemics: Ortegria, Didesmus, Ceratonia, Chamaerops, and the single family Aphyllanthaceae. This region serves as one of the centers of origin for cultivated plants, such as oats, lupines, flax, cabbage, parsley, beets, olives, grapes, and the carob tree.

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Figure 114

The Saharo-Arabian region includes parts of the tropics as well as the subtropical Sahara, Palestine, the Sinai Peninsula, Jordan, Kuwait, parts of Saudi Arabia, Syria, Iraq, and Iran. Its flora comprises 1,500 species, 25% of which are endemic. Endemic genera are few. Typical Examples include Fredolia, Nucularia, Zilla, Lonchophora, Muricaria, and Zygophyllum.

The Irano-Turanian region covers parts of Syria, Turkey, Iran, Afghanistan, Pakistan, India, China, Mongolia, and Russia. It features numerous mountain systems where speciation processes are actively underway. The region boasts many endemic genera and at least 25% endemic species, such as Calligonum, Ferula, thyme, Eremurus, Panderia, Cousinia, and Tetraena. The region's flora numbers over 500 species, some of which have been brought into cultivation: fava beans, chickpeas, apricots, figs, pistachios, almonds, and pomegranates.

The East Asian region occupies the eastern Himalayas, Assam, northern Burma, parts of Vietnam, China, Japan, southern Sakhalin, the Kuril Islands, Primorsky Krai, and Korea. The flora of this region is rich in endemic species, with over 300 endemic genera and about 20 families. The principal ones include Ginkgoaceae, Cephalotaxaceae, Trochodendraceae, and Eucommiaceae. Among the generic endemics, characteristic taxa include Pseudotaxus, Hylomecon, Kerria, Tanakea, Hovenia, Hosta, and Sasa. This area serves as one of the centers of origin for conifers and flowering plants that evolved and migrated to other Regions of the Holarctic and Paleotropics. These include crops such as rice, millet, soybeans, radishes, peaches, persimmons, the tea plant, mandarins, and oranges, which are now widely cultivated in many regions.

The Paleotropical Kingdom spans the tropics of Africa, the Arabian Peninsula, southern Asia, and the islands of the Indian and Pacific Oceans. A. Takhtajan (1974) distinguishes five subkingdoms and 13 floristic regions here. Crops introduced into cultivation from this kingdom include cotton, pumpkins, cucumbers, and gladioli. Furthermore, rice, wheat, tomatoes, corn, peppers, citrus fruits, and tobacco are grown here.

The Neotropical Kingdom serves as the center of origin for ancient Andean species of potatoes, quinoa, starchy corn, peanuts, melon and cinchona trees, rubber trees, pineapples, long-staple cotton, cassava, strawberries, and tuberous sorrel, among others.

The Cape Kingdom covers a part of Southern Africa. Despite its limited territory, over 7,000 species grow here, of which about 90% are endemic. Notable endemic families include Bruniaceae, Roridulaceae, Retziaceae, and Grubbiaceae. This kingdom is the center of species diversity for heathers. The genus Erica alone comprises 400 colorful yet attractive species, some of which are used in ornamental floriculture. Plants such as pelargoniums, amaryllis, gerberas, freesias, clivias, and agapanthus also originate from here. At the same time, this kingdom did not become the homeland of major cultivated plants; thus, grapes, apricots, peaches, and oranges were imported here from the Holarctic and other kingdoms. High aridity and low precipitation have favored the spread of xerophytic vegetation. Coniferous forests cover the mountain slopes, while deciduous forests fringe the seashores. A specific feature of the flora is the Abundance of bulbous and cormose plants. There are numerous Liliaceae, Amaryllidaceae, Compositae, and Orchidaceae. The flora of the Cape Kingdom includes families such as Proteaceae, Restionaceae, and Epacridaceae, along with over 20 genera that also occur in Australia, indicating the historical connection and unity of these continents. A similar affinity is evident between the Cape region and South America, supported by species from the Proteaceae family and the genus Drosera.

The Australian Kingdom occupies Australia and Tasmania. It comprises 13,176 species, of which 9,226 are endemic. The high level of endemism in the Australian flora highlights its antiquity and uniqueness. Australia separated from the mainland during the pre-Tertiary period. The northward drift of the continent caused a shift in its flora, increasing the proportion of xerophytic species. The flora is richest in the western and eastern regions. The flora of Western Australia shares a genetic affinity with the flora of the Cape and Neotropical kingdoms.