16 



BOTANY: PRINCIPLES AND PROBLEMS 



group of more than 130,000 species and are our most familiar 

 plants. They are divided again into two main groups, the 



I'lG. 9. — A Seed Plant (Angiosperm). Hawthorn tree (Crataegus). 



Dicotyledons and the Monocotyledons, which differ from each 

 other in the structure of the seed, leaf, stem, and flower. 



