154 
H . F. Wernham. 
As in the Ericales, traces of polypetaly remain in the Primulales. 
The petals are free in the genus Embelia of Myrsinaceae, comprising 
some sixty species, and in some species of Myrsine : of the 
Plumbaginaceae an extensive section (Staticeae) is distinguished by 
a polypetalous or subpolypetalous corolla. 
We may now approach the question of the archichlamydeous 
origin of the Primulales; and our attention seems directed naturally 
to the Centrospermae as representing the stock from which this 
cohort may reasonably have been derived. The Centrospermae 
include, approximately speaking, the Curvembryeae of Bentham 
and Hooker—a cohort of Incomplete—together with the Aizoaceae 
and the heterochlamydeous Portulacaceae and Caryophyllaceae ; the 
last named natural order includes about 40% of the species in the 
cohort, and the Chenopodiaceae with Amarantaceae, about 30%. 
In the Caryophyllaceae, which may be taken as representative 
of the main centrospermal stock, the stamens are usually borne in 
two whorls, each isomerous with the corolla, and with the members 
of the outer whorl placed opposite to the petals. There is, however, 
an unmistakeable tendency to reduction in the andrcecium and this 
tendency is realized in the Centrospermae and Amarantaceae, in 
which the stamens are typically isomerous with, and anteposed to, 
the corolla-segments. 
The carpels, again, are typically isomerous with the corolla, 
displaying at the same time a tendency to oligomery. The ovary 
is unilocular, the ovules being borne upon a free-central placenta 
formed, apparently, by the degradation of septa. In the Cheno¬ 
podiaceae and Amarantaceae the ovary is unilocular, and contains a 
solitary basal ovule. 
The caryophyllaceous flower is typically heterochlamydeous, 
like that of the stocks represented by Geraniales and Rosales 
respectively. The Chenopodiaceae and Amarantaceae appear to 
represent a tributary line determined by loss of the heterochlamy¬ 
deous character. 
The derivation of the Primulales from the alliance briefly 
sketched above is not difficult of conception. Probable lines of 
evolution are indicated in the annexed diagram. 
Starting with what may be designated the caryophylline branch 
of the centrospermal stock, represented by Caryophyllaceae and 
Portulacaceae, the main progressive line is that of economy in the 
andrcecium; this we should reasonably expect from the aspect of 
our fundamental principles. At a relatively early stage a side-branch 
