OUTLINE OF STRUCTURAL BOTANY 27 
Selecting a well known “regular” flower as an illustration of 
the typical arrangement we may examine the blossom of the 
common buttercup when the petals are fully expanded. 
In the very center are several greenish bodies, arranged about 
the receptacle, which represent the pistils. They are attached to 
this receptacle which is the summit of the axis of the little stem of 
the flower, the peduncle. (Fig. 32). 
When there is but a single pistil in a typically regular flower 
it springs from the very central point of this axis which is often 
concave at the summit as we see it at Fig. 35. About this little 
group of carpels of the buttercup, stand, at regular intervals a 
row of stamens and beyond this another and still another row. 
These rows appear to be perfect but if we were to shave them all 
off at a level just above their origin at the receptacle and should 
examine this surface by the aid of a magnifying glass of moderate 
power we would find that there is in fact only a single row of 
36 37 
Fic. 34—Nectary at base of a Buttercup.petal—a, view in front; b, longitudinal 
section. 
Fic. 35—A typically regular flower. 
Fic. 36—Diagram of arrangement of stamens in Ranunculus. 
Fic. 37—Diagram of: arrangement of stamens in Columbine. 
stamens arranged in a spiral and that this spiral line goes around 
the carpels three times as we see it in the diagram, Fig. 36, where 
the shaded curved lines represent the insertion ofthe petals and 
the small points that of the stamens. 
This arrangement is not universal nor even always found in 
the flowers of plants belonging to the same family as the buttercups. 
For example, the stamens of the columbine, which is a member of 
the great Ranunculus family, to which the buttercups belong, are 
arranged in about ten rows radiating from the central group of 
earpels. (Fig. 37). In flowers of other families there may be a 
single row of five, six, or more or less stamens or in still others, 
especially in flowers which are “irregular” the stamens may all 
be moved to one side or, as in orchids, consolidated and attached, 
to the pistil. 
Returning to our buttercup flower, beyond the spiral row of 
stamens we find the five petals, their inner borders being attached 
to the receptacle in a row just outside the ranks of the stamens. 
At the base of each of the petals is a little sac, the nectary, which 
