178 HERICDITY AND JA'^LUl'ION IN PLANTS 



first rapid spread, says Sinnott, a species becomes less 

 common the older its age of occupation. 



Reviewing these two theories, Taylor^ holds that, in the 

 flora of the vicinity of New York at least, endemism is not 

 a criterion of antiquity nor of youth, for while many 

 endemics of the flora of New York and vicinity are very 

 recent (as the hypothesis of Willis would require), and 

 while some of them are even found in the geologically 

 recent portion of the area (one. Hibiscus occuliroseus, 

 being a salt marsh plant and therefore very 'new'), 

 other forms are relict endemics (p. 167), and could not, 

 therefore, be of very recent origin. ^ 



As an example of relict (and therefore old) endemics 

 (outside the local flora region of New York, there may be 

 cited the well known case of the giant and coast redwoods 

 {Sequoia gigantea and S. sempervirens), and the begonia, 

 Hilldebrandia sandwicensis , endemic in Hawaii.' 



An example of an indigenous (and therefore relatively 

 recent) endemic, is the well-known insectivorous plant, 

 Venus fly-trap {Dioncea muscipula) , a genus having only 

 one species, i.e., monotypic (Fig. 79) . This unique plant is 

 found in sandy swamps, only in a narrow strip of country 



' Taylor, N. Endemism in the flora of the A-icinity of New York. 

 Torreya 16: 18-2^. Jan. 1916. 



' Five cases of apparently relict endemism are cited by Taylor from the 

 vicinity of New York. Torreya 16 : 18-27. Ja-"- 1916. 



' The Begoniaceae have scarcely any representatives in the islands of 

 the southern, equatorial, and Northern Pacific, but are abundant in the 

 Andes region of South America and Mexico. The endemic begonia of 

 Hawaii is regarded by MacCaughey (Bot.Gaz. 66:273-275. Sept. 1918) 

 as one of several bits of evidence that "at one time in the history of the 

 Pacific basin the Hawaiian islands were much more closely associated with 

 the Andean and South Pacific regions than they are at present. See also 

 P- 175. 



