436 BOTANICAL GAZETTE [DECEMBER 
hiatus, it becomes desirable to interpret a few more examples of 
staminate organization leading toward or into the more complex 
types of flowers. Thus may we best test our theory and see if it 
applies to petals and stamens generally, and really affords a far- 
reaching explanation of floral constitution in the angiosperms, with 
ultimately a better basis of classification. But in so doing we may 
only take up a few forms; for an exhaustive analysis of the families 
based on the necessary histological and developmental data must be 
a truly gigantic task for many years and many workers. 
Various gamopetalous flowers have the structure shown in fig. 6. 
Apparently the stamens alternate with the lobes of the corolla in 
b 
Fics. 6-8 
such forms; but on closer examination it is seen that in reality the 
axis of the component leaves has shortened to form the notches. 
This difference, so convenient in classification, therefore rests on 
very slight anatomical distinction, unless it can be found to accom: 
pany a particular juxtaposition of the ovules throughout the groups 
question. My example is from a shrub I found growing on the 
slopes of Popocatepetl, though anyone may turn to Gerardia and 
Pentstemon as equally good examples of this type of androecium. 
Again, the cruciform flower invites attention, whether it be regarded 
as an approach toward or a departure from distinctly gamopetalous 
types. For in the cruciferous flower, although the stamen is appat 
ently inserted on the common receptacle, rather than as in the dia- 
gtammatic fig. 7, there is considerable doubt if it is to be regarded 
as of discrete origin. Instead, it would seem more probable that 
