H . F. Wernham. 
15 * 
c 
be discussed fully until the other groups characterized by an inferior 
ovary (Infer®) have been dealt with, and we must therefore postpone 
the matter accordingly. 
Primulales. 
This cohort may be distinguished, like the Ericales, by the 
andrcecium ; but, unlike the Ericales, the stamens are equal in 
number to the corolla segments and placed opposite to them. This 
anteposed arrangement is generally regarded as the indication of 
the presence of an outer alternating staminal whorl in the ancestral 
stock, and so the Primulales find a place in Pentacyclidse in the 
one system, and Heteromerae in the other. An outer whorl of 
“staminodes” is often present, and the temptation arises to regard 
these as representing the modified descendants of an ancestral 
outer whorl of stamens—not only in Primulales, but throughout 
the Angiosperms where these structures occur. Modern research, 1 
however, which has been directed particularly to the members of 
this cohort, has thrown serious doubt upon the justification for 
such a conclusion, and has left quite open the general question of 
the true morphological nature of these so-called “ staminodes.” The 
discussion of this interesting question is beyond our present scope; 
it will suffice, perhaps, to say that no weight will be attached in 
these papers to the presence of these doubtful organs. 
The stamens are typically epipetalous, with short filaments, 
and set at an appreciable height in the corolla-tube ; it has been 
proved, further, that in certain Primulaceae the petals and stamens 
have a common origin, the former being developed from the dorsal 
portions of the latter. 2 We may take the present opportunity to 
observe that epipetaly of the stamens is a phenomenon wide-spread 
throughout the Sympetalae, and seems to follow naturally upon the 
evolution of the sympetalous corolla. The latter, we have seen, is 
correlated fundamentally with the principle of adaptation to insect 
visits; and epipetaly of the stamens may be regarded as a secondary 
economy tendency, 3 following upon and dependent upon sympetaly, 
This epipetaly is thus comparable with the other secondary tendencies 
to economy—oligomery of the andrcecium in zygomorphic forms, 
calyx-reduction, etc.,—to which we have drawn attention (supra, 
p. 116), and which we shall meet with in the higher sympetalous 
groups. 
1 See, especially, Eichler, Bliithendiagraninie. 
1 W. Pfeffer, Zur Blilthenentwickelung der Pvimulaceen, etc. 
Pringsheim’s Jahrb. f. wiss. Bot. viii, 194. 
3 See supra, p. 82. 
