404 Mr. Benruam on the Eriogonez, a Tribe of the Order Polygonacez. 
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 Kenigia 
(Tas. XVII. 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 
(Tas. XVII. fig. 5.); or the external segments remaining complete, one of 
the upper internal ones with one of the corresponding stamina is deficient 
(Tas. XVII. fig. 6.), the gynzecium in both cases remaining complete ; whilst 
in the hexandrous and pentandrous species (Tas. XVII. fig. 7, 8, 9.) there is a 
further reduction in the upper internal segments of the perianthium and in the 
upper stamina, and the gynzecium becomes dimerous, the upper faces of the 
ovarium with their styles and stigmata being reduced to one. 
The flowers of Calligonum, where (in the specimens I possess of C. Pallasii) 
the lobes of the perianthium are 5, the stamina 12, and the gynecium 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 (FI. Alt. 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 Polygonacea, arranged in a single series. 
The following are the leading subdivisions I should propose in the Erro- 
GONEJE. 
