233 SYSTEMATIC BOTANY 



ovary before pollination. Such seed-plants are included 

 in a division called Gymnosperms (Gr. gymnos naked) 

 and are a very ancient type. 



Seed-plants like the Buttercup, Primrose, and Bluebell, 

 produce their ovules in an ovary formed of closed carpels, 

 and belong to a more modern group called Angiosperms 

 (Gr. angeion = a vessel) ; to this group belong the great 

 majority of the seed-plants of the vegetation of the present 

 day. In the Stock and Primrose the parts of the flower 

 are in fours or fives, and the seeds contain two cotyledons. 

 Such Angiosperms are placed in a class called Dicotyle- 

 dons. On the other hand, the parts of the flowers of the 

 Bluebell and Crocus are in threes, and the embryo of the 

 seed has only one cotyledon. Such Angiosperms form the 

 class Monocotyledons. 



These classes are further subdivided according to the 

 relationships of the parts of the flower. Dicotyledons 

 with a simple perianth of free petals in one or two whorls 

 are known as Archichlamydeae (Gr. arche = beginning, 

 chlamys = a mantle), while those with a more highly 

 developed perianth, in two whorls, the petals being joined 

 together by their edges to form a gamopetalous corolla, 

 are called Metachlamydeae (Gr. meta = beyond) or Sym- 

 petalae (Gr. syn = together). 



Other subdivisions depend on (i) the relations between 

 stamens and pistil, whether the former are hypogynous, 

 perigynous, or epigynous ; and (2) the condition of the 

 ovary, whether apocarpous or syncarpous one or more 

 celled. 



We thus see that the characters of most importance in 

 classification are those to be noticed in a careful examina- 

 tion of the parts of a flower from outside inwards. The 

 classification of the above-mentioned plants may be shown 

 as follows : 



