INTRODUCTION TO THE REPORTS ON INSULAR FLORAS. 37 



DISTINCT CONTINENTAL GENERA OF VERY RESTRICTED AREAS. 



There are probably scores, or even hundreds, of monotypic continental genera confined 

 to very small areas ; perhaps not very many to such small areas as St Helena or Juan 

 Fernandez, or the islands of the Sandwich, Galapagos, or Seychelles groups; but, neverthe- 

 less, many very distinct genera have hitherto only been met with in one locality or district, 

 especially continental genera of the southern hemisphere. Of course we cannot assume that 

 they do not exist in more than one district because they have hitherto not been found else- 

 where. De Candolle (Geographic Botanique, p. 1141), in giving examples of genera of very 

 wide and very limited areas, cites insular genera only of the latter category. In the absence 

 of more exact information we can give examples of a few genera which appear to be com- 

 paratively local. Whether, like the eastern Asiatic Ginkgo (Salisburia), and the North 

 American Sequoia, they are survivors of types having a much wider distribution during 

 the tertiary period, is a question that we can only suggest. Darlingtonia and Heliam- 

 phora (Sarraceniaceas, cited on p. 36 as an example of an order of discontinuous area) are 

 instances of highly differentiated monotypic genera of a very curious order, apparently of 

 comparatively local existence, though the former ranges from the Truckee Pass to the 

 borders of Oregon. It is singular, too, that some other of the so-called carnivorous genera 

 of plants are very local. Thus, Dioncea is confined to North Carolina and the adjacent parts 

 of South Carolina. The Hamamelidese, also a very remarkable order, comprise a number 

 of monotypic genera, several of which are at present only known from single localities or 

 narrowly limited districts ; and none of them, except Liquidambar, has anything approach- 

 ing a wide range. This genus now occupies several widely separated areas in North 

 America, Asia Minor, and the extreme Eastern Asia ; but during the tertiary epoch it 

 inhabited the intervening country. The Begoniacese consist of the very large genus Begonia. 

 which is widely spread in warm countries of both hemispheres, and one very small very 

 distinct genus, Begoniella, which inhabits the Andes, and the monotypic Hillebrandia, a 

 native of the Sandwich Islands. Columellia, mentioned at p. 36, has a restricted range 

 in the Andes ; Gosela (Selaginese) is a monotypic South African genus of apparently very 

 restricted area ; AtJcinsonia (Loranthacese) is only known from the Blue Mountains in New 

 South Wales ; and Saprium (Cytinaceae) has only been gathered in one place in Eastern 

 Bengal. The number of monotypic genera of Orchidese, known from only one locality, 

 is considerable, but it is hardly worth while giving a list of names. Lapiedra and 

 Tapeinanthus (Amaryllidese) are instances of European local genera, the former being 

 found only in Southern Spain, and the latter in Southern Spain and Tangiers. Finally, the 

 distribution of the Burmanniacea3 is interesting in this connection. Burmannia itself is 

 spread nearly all over the tropics, and Gymnosiphon is represented in America, Africa, and 

 the Malayan Archipelago ; while several others which exhibit some marvellous deviations 



(BOT. CHALL. EXP. — INTRODUCTION — 1885.) 6 



