The Pentacyclidce. 
149 
Lennoaceae have reached a climax of specialization in the complete 
loss of chlorophyll and the adoption of a saprophytic mode of 
existence. 
Above all it must be borne in mind that the Ericales have, in 
the bulk of their constituent species, taken the fundamental step 
in the direction of adaptation for insect visits—namely, fusion of 
the petals to form a sympetalous corolla. This step from the 
archichlamydeous ancestral stock was taken, we must presume, at 
a relatively early stage in the progress of the tendency to 
economy—-before the latter had proceeded so far as to “ produce ” 
the Geraniales, if we may so express it (see Fig., p. 151). This 
found expression in the typical ericalian flower with two whorls of 
stamens, multilocular ovary, and numerous ovules. The continued 
working of the economy tendency within the cohort achieved its 
final result in the “ production ” of the epacridaceous flower, with 
a single whorl of stamens, and, in over 65% of the species of 
Epacridaceae, with but a single ovule in each loculus of the ovary. 
Sympetaly has, further, been followed in the last-named natural 
order by epipetaly of the stamens, and this, as we have already 
seen, is significant in connection with economy of material ( supra ,, 
p. 82). In Diapensiaceae, too, the stamens are epipetalous. The 
floral character of the Epacridaceae, together with their specialized 
habit and limited distribution, leads us to the supposition that this 
natural order represents the climax of evolutionary tendencies 
along the ericalian line; and, further, we are driven to the con¬ 
clusion that the latter ends blindly at this point, in view of the fact 
that there seem to be no groups among the rest of the Sympetalae 
which reveal any indication of having been derived from a sympe¬ 
talous ericalian stock. Thus viewed, the Ericales represent one 
of the threads, and that the most primitive, in the polyphyletic 
origin of the Sympetalae. 
We have now to consider the origin and affinities of the 
Vaccinioideae. This group has hitherto been associated closely 
with Ericaceae, and is included by Bentham and Hooker as a 
natural order—Vaccinieae—of the Ericales ; Engler goes so far 
as to include them in the Ericaceae, giving them tribal status only. 
This close association is based on the great similarity in structure 
between the flowers of the hypogynous Ericaceae and Vaccinioi- 
deae—a similarity which extends not only to the habit and number 
of stamens, carpels, and ovules, but even to the shape of the 
corolla and to the details of the structure of the stamens, with 
