CHAPTER XXIX 

 THE MONOCOTYLEDONS 



This group of plants, although only about one-fifth as numer- 

 ous as the dicotyledons, is nevertheless of great importance on 

 account of its significance in supplying extremely valuable food 

 plants and also by reason of its remarkable anatomical organiza- 

 tion, which has been the cause of much speculation and dispute. 

 In this large group of the angiosperms we have exemplified a 

 practically complete absence of secondary growth coupled with 

 a complicated arrangement of the numerous though slender 

 fibrovascular strands. The absence of secondary growth has led 

 to the association of the monocotyledonous angiosperms with 

 the ferns and their allies. This view of their affinities has been 

 reinforced at various times by the discovery of leaves and even 

 inflorescences in Paleozoic strata which have been referred to 

 monocotyledonous affinities. The foliar and reproductive parts 

 from Paleozoic deposits have, however, in more recent times 

 been clearly recognized as the parts either of cryptogamous or 

 of gymnospermous types not related even remotely to the angio- 

 sperms. There is accordingly no reason based either on the 

 possession of cryptogamic characters or on very ancient occurrence 

 as fossils which justifies the view that the monocotyledons are 

 the more primitive group of the angiosperms. The evidence, 

 in fact, when considered in the light of the general principles of 

 comparative anatomy, points in quite the opposite direction and 

 seems to indicate that the group under consideration is derived 

 from herbaceous representatives of the dicotyledons. 



A characteristic feature of organization of the axis in the 

 monocotyledons is the scattered distribution of the fibrovascular 

 bundles. These, instead of being arranged in the circular fashion 

 which usually distinguishes the structure of the herbaceous stem 

 in the dicotyledons, are disposed through the transverse section 

 of the organ. An examination of the seedlings and reproductive 



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