6 ON THE PROTEACE^ OF JUSSIEU. 



the plants of Madagascar and the Isles of France and 

 Bourbon. 



The bursting of the antherse has, it is true, been gene- 

 rally observed, and many of its most unusual modes have 

 been introduced into the characters of genera ; but the ex- 

 amination of these organs, at a still earher period, has been 

 universally neglected ; and hence the very imperfect know- 

 ledge which, even now, is possessed of their real nature in 

 two of the most remarkable families of plants, the Orchidese 

 and Asclepiadese. 



Examples of the great advantage of observing the antherse 

 in this early stage will hereafter be given in my general re- 

 marks on the order which is the proper subject of this essay. 

 But I trust I shall be pardoned for here introducing some 

 account of their structure in Asclepiadese, as it will enable 

 me not only to bring forward the most striking proof of the 

 importance of this consideration with which I am acquainted, 

 but also, as I apprehend, to decide a question which has 

 long occupiedj and continues to divide, the most celebrated 

 botanists. 



The point in dispute is whether this order, comprehend- 

 ing Asclepias, Cynanchum, Pergularia, Stapelia, and several 

 genera, at present confounded with these, ought to be re- 

 ferred to Pentandria or Gynandria, and, if to the latter, 

 whether the antherse are to be considered as five or ten ; all 

 of which opinions have had advocates of the greatest name 

 in the science. 



According to Linnseus, Jussieu, and Richard, they belong 

 to Pentandria. 



Linnseus has assigned no reason for his opinion, which, 

 however, it appears he retained after he became acquainted 

 with the observations of Jacquin and Rottboell ; but it is 

 17] probable he was induced to adopt it more from the con- 

 sideration of the close analogy these plants have with the 

 manifestly pentandrous Apocinese, than from regarding them 

 as strictly referable to this class ; for, in his natural generic 

 characters of Asclepias and Pergularia, he very clearly de- 

 scribes both these genera as gynandrous. 



Jussieu has entered more fully into the subject, but seems 



