CHAPTER XVIII, 



NATURAL SYSTEM OF JUSSIEU, 



It is more than forty years since the arrangement of 

 Jussieu was approved by the Royal Academy at Paris. 

 Other systems had determined some of the natural affi- 

 nities, but they offer at the same time numerous dis- 

 parities which render them very defective. Linnaeus 

 and Adanson, one in his Fragments, and the other in his 

 Families, had done much, and the elder Jussieu had 

 arranged in natural groups the plants of the Royal 

 gardens at Paris, but he was too diffident to publish 

 an arrangement which he regarded as incomplete. 

 Adopting the same principles, his relative and success- 

 or has traced with unrivalled success the order of na- 

 ture, and detected the affinities for which others had 

 sought in vain. His three primary divisions are found- 

 ed on the form of the embryo. The first embraces 

 those plants whose seeds are destitute of lobes, and are 

 named acotyledons ; the second includes all plants with 

 a solitary lobe and termed monocotyledons, while 

 plants whose seeds are furnished with a pair of lobes 

 are comprehended in the third division. 



The number of the petals and the relative situation 

 of the different parts of the flower, furnish a character 

 for each of his classes ; while the orders into which 

 these classes are distributed, are less determinate, 

 being established on the structure of more variable 

 organs. 



