Phytogeographic Realms According to Turrill

The following points highlight the four major types of phytogeographic realms according to turrill. The types are: 1. The Northern Realm 2. The Paleotropical Realm 3. The Neo Tropical Realm 4. The Southern Realm.

1. The Northern Realm:

The Northern Realm is subdivided into following 8 regions:

i. Artie and Sub-artic Region:

Includes Alaska, Greenland, Iceland, northern part of Scandinavia, and Northernmost part of Russia. Predominating plants are Willows, Birches, Junipers, some plants of Ericaceae, etc. “The Artie flora is fairly old; it is preglacial and extended much further south in the glacial Epoch”.

ii. Boreal Region:

Northern part of Eurasia with a coniferous belt.

iii. Central European Region:

Major part of Europe, Siberia and Mongolia with broad-leafed forests, Quercus robur, Q. petraea, Fagus sylvatica, species of Fraxinus, Tilia, Acer, Populus, etc. predominating.

iv. Mediterranean Region:

Areas on the north and south of Mediterranean sea and Madeira, the Canaries, the Azorses, and the Cape Verde Islands; the characteristic vegetation represented by Pinus halepensis, Quercus ilex, Q. coccifera. Arbutus, Myrtus, Olea, Juniperus, Laurus, Spartium, Ruscus, etc. Mediterranean flora is a relatively old one with a large number of Tertiary relics. The area was not glaciated during the glacial Epoch.

v. Central Asiatic Region:

Asiatic Russia, Mongolia, Turkistan, N. Tibet; mostly arid tracts. The aridity in central Asia is of very ancient in character having originated in the end of Cretaceous. Plants of Mediterranean Realm and of the Near East migrated to this area to some extent.

vi. Region of Near East:

Includes N. Africa, the Balkan peninsula, Anatolia, Israel, Jordan, Syria, Iraq, Iran, Afghanistan and Pakistan, — home of the Date Palm and Smyrna fig; mainly xerophytic plants and those comming from neighbouring countries.

vii. Eastern Asiatic Region:

Includes China, East Tibet, Upper Burma and Japan. Vegetation is sparse in N. China with Metasequoia, Larix and deciduous Angiosperms. Grassland is characteristic of E. Tibet, Rhododendron, Mahonia, Camelia, etc. grow in Yunnan and N. Burma and mixed evergreen vegetation covers the rest of China.

Japan has forests of Larix, Cryptomeria, Thujopsis, Cercidiphyllym, Salix, Prunus, Pyrus, etc. in the north and Qucrcus, Myrica, Bauhinia, Ficus, Hibiscus, Cycas, etc. are found in the South. Cycas revoluta is Japanese while C. circinalis grows in China.

viii. North American Region:

Comprising Artie and sub-artic zones and temperate zone of .N. America, Mexican subtropical zone and tropical zone of N.America also included here. Tsuga, Pseudotsuga, Thuja, Taxodium, Sequoiadendron, Quercus, Lithocarpus, Robinia, Opuntia and other cacti, Magnolia, Crossosomataceae, Garryaceae are predominating; wide belt of Conifers present in the north.

2. The Paleotropical Realm:

Paleotropical Realm is subdivided into 5 regions as noted below:

i. Indian Region:

Indian subcontinent excluding Pakistan, but including central and lower Burma and Sri Lanka. Conifers in the Himalayas and Assam with Rhododendron, Rosaceae, Magnoliaceae, Primulaceae; Shorea at the foot of the hills; Dipterocarpaceae, Ficus, Palms, etc. in other parts; Rhizophoraceae and other halophytes in the littoral forests; Ferns and Orchids abound in Malabar, Sri Lanka, Central and South Burma.

ii. Malaysian Region:

Malayan peninsula, Malayan Archipelago, Philippines, Formosa, New Guinea. One of the richest floras of the world; Dipterocarpaceae, Rafflesiaceae, Moraceae, Palms, Bamboos, Orchids, etc.

iii. Tropical African Region:

Major part of Africa south of Sahara; Myrsinaceae, Cyanastraceae, Oliniaceae, Palms, etc.

iv. Mascarene Region:

Malagasi and other adjacent islands; natural vegetation almost totally destroyed. Chlaenaceae, Didieriaceae, etc. are however characteristic.

v. Pacific Region:

Comprising Hawai groups of Islands, Fiji, Samoa, New Caledonia Tahiti, The Marquessas, etc. Degeneriaceae among others is the predominant family.

3. The Neo Tropical Realm:

Neo tropical Realm consists of only one region:

i. Tropical and subtropical American region:

Mexico, Central America, West Indies, Northern S. America. Forests are characterised by the presence of Cunoniaceae, Lecythidaceae, Malpighiaceae, Cyclanthaceae, Julianiaceae, Alstroemeriaceae, Andropogon, Cymbopogon. Trachypogon, etc.

4. The Southern Realm:

Southern Realm is divided into 5 regions:

i. S. African Region:

Families, like Acharlaceae, Grabbiaceae, Geissolomataceae, Roridaceae, etc. and the genera Crassula, Pelargonium, Rochia, Erica, Protea, Leucadendron, Mesembryanthemum etc. predominate.

ii. New Zealand Region:

Agathis australis forms a mixed evergreen forest with Nothofagus, Hebe, Perenthya, Drimys, Uncinia, etc.

iii. Australian Region:

Families like Pittosporaceae, Epacridaceae, Treman- daceae, Stackhousiaceae, and genera like Grevillia, Boronia, Cailistemon, Casuariha, Drvandra. Banksia, Eucalyptus, Melaleuca, Acacia, Leptospermum, Prostranthera, Xanthorrhoea, etc. predominating in the forests.

iv. Temperatre S. America:

Including Chili, Argentina, Uruguya, Paraguya, etc. having Bignoniaceae, Bromelfaceae, Aexotoxicaceae, Myzodendraceae, etc. as components of the vegetation.

v. Antartic Region:

Only a few species like Deschampsia antartica, Colobanthus crassifolius, etc.