PART TV 



THE KINDS OF PLANTS 



number of PLANTS. Above 125,000 distincl kinds or 

 species of seed-bearing plants are known and described. 

 Probably little more than one-half of the total number now 

 existing <>n the earth are known. Even in the older coun- 

 tries and regions, seed-bearing plants heretofore unknown 

 to science are discovered now and then. Outlying regions 

 are relatively little known botanically. The larger pari 

 of Africa, South America, Central America, China, Ceu- 

 tral Asia, and the tropical islands arc only imperfectl) 

 explored for plants. Cryptogamous plants are far more 

 numerous in kinds than seed-plants, and manj kind. as, 

 for example, various bacteria arc almost infinite in 

 numbers of individuals. In the lower ranges of crypt 

 anions plants, as in fungi and bacteria, tnanj new kinds 

 are constantly being described even in countries in which 

 thc_\ have been mosl carefullj Btudied. 



species. Each kind of plant is called a species. 

 There is no absolute mark or characteristic of a Bpecies. 

 Between man} kinds there are intermediate forms, and 

 some kinds \,ir\ immensely under different conditions. 

 What one botanist considers as b distinct species, another 

 botanist maj regard as onlj a varietj or form of another 

 species. No two botanists agree as to the number of 

 species in a 1 1 \ region. Species are not things in them- 

 selves. In practice, anj kind of plant which i- distincl 



enough to be r gnized bj n description, and which i> 



fairlj constant over b considerable territory, is called a 



