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VII. On the Structure and Affinities of Arachis and Voandzeia. 

 By George Bentham, Esq., V.L.S. 



Read May K-t, 1838. 



J. HE genus Arachis, hitherto consisting of the single species A. hypogœa, 

 was universally described by the older authors as having a bipartite calyx, a 

 resupinate corolla, the pistil included within the staminal tube, and the style 

 of about the length of the ovarium : the flowers were all considered as pedun- 

 culate, and it was observed tiiat the upper flowers were usually sterile, wiiilst 

 in the lower ones the peduncle became reflexed and lengthened till it reached 

 the ground, which it entered, and the fruit was there matured. Such is the 

 idea given in the Genera Plantar um of Linufeus and of Jussieu ; and Lamarck, 

 in his Illustrations, figures various details of the reproductive organs, entirely 

 in accordance witli the above character. Poiteau subsequently (according to 

 Poiret, Enci/cl. Méth. Suppl.) remarked, that what was usually taken for the 

 peduncle of the flower, was in fact the tube of the calyx, within the base of 

 which is contained the ovarium ; and, accordingly, De Candolle and other 

 modern botanists describe a calyx with a long thread-like tube and a bipartite 

 limb, a corolla, somewhat resupinate, inserted at the top of the tulie with the 

 stamina ; an ovarium borne on a short stipes within the base of the tube, with 

 a long thread-like style and a bearded stigmate ; the stipes of the ovarium is 

 described as lengthening very rapidly after fecundation, so as to form that rigid 

 peduncle which had been already observed to reach the ground before the 

 fruit could mature itself. The legume is well known to be oblong, reticulated, 

 indéhiscent, and often somewhat torulose, and to contain from one to three 

 seeds, witli thick fleshy cotyledons and a straight radicle. 



With these data great difficulties have occurred as to the immediate affini- 

 ties of Arachis amongst the numerous genera composing the order of Legii- 



