Rubiales. 
231 
But the prime distinction between Rubiales and Umbelliflora* 
rests upon the constant sympetaly of the former, and the constant 
presence of a single ovule only in each loculus of the ovary in the 
latter. Umbelliflorae may be regarded as the representatives of a 
side-branch from the calycifloral (rosalian) plexus, determined by 
the complete realization of the calycifloral tendency of the latter, 
and by the umbellifloral type of inflorescence together with the 
reduction of the ovules to one per ovary-cell. Before the latter 
tendency was fully realized, a side-branch determined by sympetaly 
emerged, terminating with the Rubialian Stock. 
The suggested trend of evolution is indicated in the accompanying 
diagram. The existing groups nearest to the Umbellifloral stock 
are the woody Araliacese and Cornacete,—especially, perhaps, the 
former, in which the number of carpels exceeds two in the flowers 
of 75% of the family ( i.e. t over 280 species). From the end of the 
line of progressive reduction of the carpels to two the side-line to 
Umbelliferae emerges, dominated by further elaboration of the 
inflorescence, the formation of “ray” florets, and fruit-specialization. 
The Umbelliferae, moreover, are mostly herbaceous, a condition 
already alluded to as usual among the most advanced members of 
the progeny of particular stocks among the higher flowering plants; 
analogies to the relationship between Umbelliferae and the woody 
Araliaceae are afforded by Labiatae and Verbenacese, by Asclepia- 
daceae and Apocynaceae, by Dipsacales and Rubiaceae, and so on. 
In fact, the growing shoots in the evolutionary tree, just as in a 
natural tree, are woody at the base and herbaceous at the tip. 
The single offshoot from the Rubialian Stock is determined by 
the tendency to irregularity in the corolla, oligomery of the androe- 
cium, and a uniovulate ovary, and leads to the Dipsacalian Stock. 
Low down upon this offshoot a short branch arises leading to 
Rubiaceae, the living representatives of the Rubialian Stock; further 
up, already exhibiting traces of the dipsacalian tendencies, appears 
the caprifoliaceous branch. Starting from the Dipsacalian Stock, 
aggregation with zygomorphy of outer florets leads to Dipsacaceae; 
while Valerianaceae, with excessive asymmetry but with traces of 
an ancestral polycarpellary ovary, represent the closest existing 
approximation to the Dipsacalian Stock. 
The Rubiales present one or two interesting and familiar 
problems which are scarcely within our province, but which we may 
