H. F. Wernham. 
380 
of Parietales generally. This section of Parietales is shewn in the 
diagram as emerging at an early stage from the calycifloral line. 
From the Geranial Plexus two “ sympetalous ” lines diverge ; 
one of these led directly to Ericales. The three groups of 
Sympetalae so far mentioned in this summary are peculiar in the 
character of an andrcecium of tw r o or more whorls of stamens, or 
having the indication of two whorls by anteposition of the stamens 
to the corolla-segments (Primulales). They are thus intermediate 
between Archichlamydeae and the majority of Sympetalae (Tetra- 
cyclideae), since they have made little or no general advance upon 
the former series in respect of the Economy Principle. For this 
reason they are grouped together in our modern systems, as 
Pentacyclid^e by Engler, and Heteromera- by Bentham and 
Hooker. This grouping is, however, clearly unnatural, for we have 
seen that each of the three cohorts has a separate proximate 
archichlamydeous ancestry. 
Primulales, Ericales, Ebenales, all have for the most part 
flowers with a superior ovary; but the exceptions to this are 
important. The Primulales reflect the slight tendency to epigyny 
occurring in their caryophylline ancestry. In certain Ebenales 
appears the epigyny which is the main tendency of Parietales as a 
whole (see diagram, p. 379). But Ericales provide the most notable, 
exception, namely, the tribe Vaccinioideae of Ericaceae. These, 
unlike the rest of the Ericales, have epigynous flowers ; and we 
nave raised the question (Chapters III and VIII) whether this 
tribe may not be descended from the calycifloral rather than from 
thahypogynousgroups of Archichlamydeae. In thiscase Vaccinioideae 
would represent the Pentacyclidae of the Calycifloral Plexus— 
otherwise unrepresented—and so would stand on the direct line to 
the Campanal Stock. The close resemblance and continuity, 
however, between Vaccinioideae and the hypogynous Ericales in 
most of their essential characters makes an alternative view more 
acceptable, namely, that Vaccinioideae represent a special line of 
epigyny emanating directly from Ericaceae. 
Each group of Pentacyclidae represents the terminal point of a 
branch of the evolutionary tree; where, then, is the line leading 
from Archichlamydeae to the rest of the Sympetalae with superior 
ovary ? For the answer to this question we have been led to 
postulate a second line emergent from the Geranial Plexus, the 
first being the ericalian line. There are, unfortunately, no pentacyclic 
forms to help us to cross this phyletic rubicon ; but once crossed, 
