THF. AMKRICAN BOTANIST 103 



TIk- Ainericati Intus or Xcluinho is often creditcil witli this 

 kind of tlistriljution. or rather, lack of it. The j)lant is so 

 remarkable in both leaf and blossom a> to attract the atten- 

 tion of e\er\bod\- who ajjproaches it and its comparative 

 rarit\" natnralK' lead> l'> im warranted conclusions. 



To be >ure there are \arions plants that inhabit very 

 limited portions of the earth's >urface. The \'enus' fly-trap, 

 for in>tance. i> f( nmd oidv in the North Carolina marshes 

 near the coast, and the insectivorous Ihirlijujtojiia is known 

 onlv from the sierra> of California and Orej^on. but most 

 plants are more widelv distributed. Nor is such distribution 

 hap-hazard or disconnected. Kach kiml of plant has a defi- 

 nite ran,i(e that in the case of all ordinary forms can be indi- 

 cated with considerable exactness. In general, plants are 

 sui)pose(l to ha\e spread outward from their point of origin 

 until thev encountered some barrier to their further progress, 

 and thu> are conhned to ver)- definite areas. There are. how 

 ever, certain phases of distribution that have ever been a 

 puzzle to botanists. Among these are the occurrence of col- 

 onies of the hart'>-t<>ngue fern in central New York and in 

 Tennessee but nowhere else in America. The plant is com- 

 mon along ditches antl hedge banks in England and the (jues- 

 tion is still how the colonies arose in the Western Hemisphere. 

 .Another fern .IsHciiiiiiii altcnnins, is found in a single can- 

 \nn in .\rizona and not encountered again until the Hima- 

 la\a mountain> are reached, more than ten thousand miles 

 away! In sf^me cases, w^hen there are outlying colonies at a 

 distance from the main body of the species there is evidence 

 to show that the species was once more widely distributed and 

 has since contracted its area, but in other instances the species 

 ma} be extending its range into new territory. Reports of 



