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XV. On Two Genera of Plants from Chile. By John Miers, Esq., F.B.S, F.L.S. 8fc. 



Read November 18 and December 2, 1851. 



AMONG the few very interesting plants which I was enabled to collect during my rapid 

 journey over the Cordillera in 1825, were the two following, which being yet undescribed, 

 may perhaps claim the attention of the Linnean Society. The first evidently belongs to 

 the tribe of the JEriogonece, of which a monograph by Mr. Bentham was read before the 

 Society in 1835, and subsequently published in the 17th volume of its Transactions. It 

 differs from all others of the tribe in its habit, for its very slender ramifications are 

 always dichotomously divided in every axil, and its solitary involucre, on a lengthened 

 capillary pedicel, springs from the middle of each bifurcation ; it is however easily distin- 

 guishable from the rest by the proportion of its floral parts in a manner to be presently 

 noticed. All the Eriogonece hitherto discovered in South America have been found on 

 the western side of the Andes, and this is probably the first instance known of their 

 occurrence on the eastern declivity. 



The learned author of the monograph above quoted, states that he does not agree with 

 Dr. Meissner and M. DeCandolle, who infer the normal number of the stamens in the 

 Polygonacece to be double that of the lobes of the perigonium, and that in all instances 

 occurring with a less number of stamens, this diminution is alone attributable to the 

 abortion of those parts. Mr. Bentham, on the contrary, shows that this relation is not 

 at all manifest, and he endeavours to prove that the normal number of floral parts 

 is always ternary, the six lobes of the perigonium being biserial, the nine stamens in 

 three series, and the ovarium surmounted by three styles and three stigmata. This 

 arrangement, however, is far from general, for the greater number of genera present only 

 five divisions of the floral envelope, with six, eight or nine stamens. Atraphaxis, not- 

 withstanding, offers a binary arrangement of its parts, viz. four lobes in the perianthium 

 in two rows, six stamens with two styles, and two stigmata. 



The discrepances here alluded to may, however, be reconciled, if we pay attention to the 

 following circumstances. There does not seem any apparent reason why botanists should 

 have constantly regarded the floral envelopes in the Polygonacece as a perigonium or 

 perianthium, words intended to express a confluence of calyx and corolla into one common 

 floral covering ; but here the parts constituting such envelope manifestly bear the usual 

 characters of a distinct calyx and corolla, for the floral segments are divided to the base, 

 and exhibit their origin externally upon an annular hypogynous ring, that serves to sup- 

 port the stamens as well as the stipitate ovarium : they are always in two or more whorls, 

 are deeply imbricated, the external series being of a somewhat denser texture, and although 

 petaloid, these segments have every claim to be regarded as so many sepals, while the 

 VOL. xxi. v 



