Chapter V —91— Types of Areas 



12. Australian Type. — Within the limits of Australia there are 

 numerous and very interesting cases of discontinuous areas, having 

 separate portions in eastern and western Australia, the intervening 

 zone in central Australia forming a botanico-geographical region known 

 as Eremea. This zone varies greatly in size and shape, as a result of 

 which the discontinuous areas have diverse configurations. 



13. Antarctic Type. — Here are included the discontinuous areas of 

 species and genera found on the Antarctic mainland and also in the 

 southern part of South America, New Zealand, Australia, South Africa, 

 and on the various islands scattered between them — St. George, 

 Kerguelen Land, Macquarie Island, etc. It is understood that the 

 parts of these areas located on the Antarctic mainland are now repre- 

 sented by plants found only in a fossil state. As examples of this type 

 of area we may mention the areas of the genera Nothofagus and Fitz- 

 roya. 



The above-enumerated thirteen types do not by any means cover 

 the entire diversity of discontinuous areas. It suffices to mention the 

 existence of areas having one portion in the northern and one in the 

 southern hemisphere. For instance, in Tierra del Fuego and southern Pat- 

 agonia there are found a number of boreal plants; also in Australia 

 {e.g., the genus Veronica); and so on. We have not attempted to list 

 all the types of discontinuous areas, since that would be well nigh im- 

 possible, but we believe that the types enumerated show quite clearly 

 their great diversity and the need of similarly diverse explanations as 

 regards their origin.* 



References: 



Beatus R., 1936: Die Kerow/co-Gruppe Agrestis des Sektions Absinebe. Ein Beitrag 

 zum Problem der Artbildung (Zeitschr. ind. Abst. und Vererb., Vol. 71, No. 3). 



Bradn-Blanquet, J., 1923: L'origine at le developpement des floras dans le massif 

 central de France (Paris-Zurich). 



Bush, N. A., 191 7: The most important terms employed in floristic phytogeography 

 (In Russian; Jour. Russ. Bot. Soc, Vol. 2, No. 1-2). 



Chevalier, A. and Gu£not, L., 1925: Biogeographie {In Martonne, "Traite de 

 g6ographie physique", Paris). 



Christ, H., 1913: tjber das Vorkommen des Buchsbaumes (Btixiis sempervirens) in 

 der Schweiz und weiterhin durch Europa und Vorderasien (Verhandl. Naturf. Ges. Basel, 

 Vol. 24). 



Clements, F. E., 1934: The relict method in dynamic ecology (Jour. EcoL, Vol. 22, 

 No. i). 



de Candolle, Alph., 1855: G^ographie Botanique Raisonnee, Vols. I, II (Geneva). 



DiELS, L., 1906: Die Pflanzenwelt von West AustraUen (/« Engler u. Drude, 

 "Veget. d. Erde", Vol. VII, Leipzig). 



Dlels, L., 1908: Geographic der Pflanzen (Berlin; 3rd ed., 1929). 



* Irmscher (1929) makes an attempt to classify discontinuous areas, and we give 

 below the more important types included in this classification (for further details see 

 Irmscher). The figure i stands for North and South America, 2 for Europe-Africa, 3 for 

 Asia, and 4 for Austraha. 



i) Areas distributed in 1.2 6) Areas distributed in 1.2.3.4. 



2) " " " 1.2.3- 7) " " " 2.3.4. 



3) " " " I.3- 8) " " " 2.3. 



4) " " " 1.3.4. 9) " " " 3-4. 



5) Southern types of discontinuity: 10) Areas linuted to some one continent (r, 2, 3, or 



a) 1.4. c) 2.4. 4). 



b) 1.2. d) 1.2.4. 11) Areas of plants distributed on oceamc islands. 



