THE 
HEW PflYTOIiOGIST. 
Vol. X, Nos. 9 & io. 
Nov. & Dec., 191 i. 
[Published December 23rd.] 
FLORAL EVOLUTION: WITH PARTICULAR REFERENCE 
TO THE SYMPETALOUS DICOTYLEDONS. 
By H. F. Wernham. 
V. Tetracyclid/E : Part II. Tubiflor;e. 
E now approach the study of what is in some respects a 
remarkably natural group, the key-note of which is 
zygomorphy, of the kind independent of close aggregation of flowers 
{supra, p. 81). This zygomorphy is coupled with a tendency, fully 
realized in the majority of the forms concerned, to oligomery of the 
andrcecium—a secondary economy tendency, following more or less 
directly upon the bilateral symmetry of the flower. The primary 
economy tendency is thus completely realized in this group as in 
the Contortae,—at least, in so far as sporophyll numbers are 
concerned; while a material and essential advance upon the latter 
cohort has been made in the direction of general adaptation to the 
reception of insect-visitors. 
We shall meet, however, with an extensive primary economy 
tendency in respect of the megasporangia, the ovules being constantly 
two, only, per sporophyll in over 40% of the total number of species 
of Tubiflorae. This tendency, it will be remembered, is not a marked 
feature in Archichlamydeae, nor, indeed, among the Sympetalae 
which we have considered so far. 
A striking feature of the Tubiflorae is reflected in the fact that 
the large majority of the species comprised in this extensive group 
are herbaceous. We need only mention the familiar Convolvulaceae, 
Boraginaceae, Solanaceae, Labiatae and Scrophulariaceae in illustra¬ 
tion of this ; and in the light of our observations in the preceding 
chapter {supra, p. 222), this feature possesses considerable importance 
as significant of advance. 
