404 Mr. Bentham on the Eriogoneae, a Tribe of the Order Polygonacese. 



owing to a general substitution of the binary for the ternary arrangement ; 

 two external and two internal segments of the perianthium, two stamina in 

 each row, two styles and stigmata with a biangular ovarium. In Kosiiigia 

 (Tab. X\'II. fig. 4.) there is a still further although regular reduction ; the 

 inner segments of the perianthium and two rows of stamina are wanting, 

 leaving a perianthium with three segments opposed to the angles of the ova- 

 rium, three stamina opposed to its faces (occasionally reduced to two), and a 

 triangular ovarium with three styles and stigmata. According to the same 

 principle the Polygona will be found to be always irregular, there being a 

 constant contraction of the upper side of the flower (next to the axis of the 

 plant). Thus in the common pentamerous octandrous species, either the 

 upper external segment of the perianthium is wanting, the two upper in- 

 ternal ones are brought close together, and one of their stamina is wanting 

 (Tab. XVII. fig. 5.) ; or the external segments remaining complete, one of 

 the upper internal ones with one of the corresponding stamina is deficient 

 (Tab. XVII. fig. 6.), the gjmoecium in both cases remaining complete ; whilst 

 in the hexandrous and pentandrous species (Tab. XVII. fig. 7, 8, 9.) there is a 

 further reduction in the upper internal segments of the perianthium and in the 

 iipper stamina, and the gynsecium becomes dimerous, the upper faces of the 

 ovarium with their styles and stigmata being reduced to one. 



The flowers of CaUigomtm, where (in the specimens I possess of C. Palla.s'ii) 

 the lobes of the perianthium are 5, the stamina 12, and the gynsecium tetra- 

 merous, are evidently irregular. Their normal state may possibly be pentame- 

 rous, 5 external and 5 internal segments of the perianthium, 15 stamina in 

 three rows of 5 each, and a 5-angular ovarium, with 5 styles and stigmata. 

 In support of this opinion it may be mentioned that Ledebour {Fl. Jit. ii. 207.) 

 states that the number of styles varies frum 2 to 5 : it has long been observed 

 that the number of stamina is also variable, not exceeding 15 ; and in one of 

 the flowers I opened from my own specimens there were four inner and two 

 outer lobes of the perianthium. The stamina being connected at the base 

 appear in this, as in other Polygonacece, arranged in a single series. 



The following are the leading subdivisions I should propose in the Erio- 



G0NE£. 



