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VII. On the Structure and Affinitigs of Arachis and Voandzeia. 
By Georce BENTHÁM, Esq., F. L. S. 
Read May Ist, 1838. 
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THE genus Arachis, hitherto consisting of the single species À. hypogea, 
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 that the upper flowers were usually sterile, whilst 
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 Plantarum of Linnæus and of Jussieu; and Lamarck, 
in his Illustrations, figures various details of the reproductive organs, entirely 
in accordance with the above character. Poiteau subsequently (according to 
Poiret, Encycl. 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 tube 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, 
indehiscent, and often somewhat torulose, and to contain from one to three 
seeds, with 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 Legu- 
