Vegetable Physiology. 



117 



. duced to five, of which the Root, the Stem, and the 

 , v s being subservient to the growth and preservation of 

 ^ Tant, are named Organs of Nutrition ; while the Flowers 

 A Fruit, whose office it is to continue the species, are the 

 Organs of Reproduction. 

 S e fore examining these in succession, it is necessary to enter 

 a short explanation of some circumstances, to which allu- 

 has already been made, both in our articles on the present 

 biect and in those on Natural Botany. We have seen that 

 11 vegetables are first divided into Flowering plants, or Vas- 

 • lare°s and Flowerless plants, or Cellulares, and that Vascu- 

 lares are further divided into the great classes, Exogenae and 

 EnaVena?. We propose, before going farther, to give such 

 explanations, and such engravings in illustration of the differ- 

 ences of structure on which these divisions are founded, as to 

 fix them more firmly in the mind of the student. 



The cellular structure is the most obvious physiological cha- 

 racter of the Acotyledonous, or flowerless plants, of which it 

 forms the entire substauce. By this they are distinguished 

 from the Cotyledonous, or Vascular plants, which possess not 

 only cellular tissue, but spiral vessels and woody fibre. This 

 distinction may pass without farther remark at present. Ex- 

 owena? and Endogenae, or Dicotyledons and Monocotyledons, 

 are distinguished from each other by obvious physical proper- 

 ties, both in the structure of their internal organs, and of their 

 leaves and seed. The peculiar characters of Endogenae are 

 shown in 



Figure 9. 



a 



a represents the transverse section of a stem of sugar cane, 

 showing no medullary rays, nor concentric layers, but appearing 

 to be composed of little else except cells and membranes in a 



