PHARMACEUTICAL BOTANY 
138 
and may be either green or colored. When collected in a whorl at 
the base of the peduncle they form an involucre, the parts of which 
are sometimes imbricated or overlapping, like shingles. This is gen- 
erally green, but sometimes petaloid, as in the Dogwood. The 
modified leaves found on pedi- 
cels are called bradeolar leaves. 
The Spat he is a large bract en- 
veloping the inflorescence and 
often colored, as in the Calla, or 
membranous, as in the Daffodil. 
Indeterminate Inflores- 
cences. — In the indeterminate 
or axillary anthotaxy, either 
flowers are produced from base 
to apex, those blossoming first 
which are lowest down on the 
rachis or from margin to center. 
The principal forms of this 
type are: 
Solitary Indeterminate. — The 
simplest form of inflorescence 
in which a single flower springs 
from the axil of a leaf. A 
number of these are generally 
developed on the same stem. 
Example: Periwinkle. 
Raceme, or simple flower- 
cluster in which the flowers on 
pedicels of nearly equal length 
are arranged along an 'axis. 
Examples: Convallaria, Cimi- 
cifuga, and Currant. 
Corymb, a short, broad cluster, differing from the raceme mainly in 
its shorter axis and longer lower pedicels, which give the cluster a 
flat appearance by bringing the individual florets to nearly the same 
level. Example: Cherry. 
Umbel, which resembles the raceme, but has a very short axis, and 
ax 
Pig. 63. — Photomicrograph of longi- 
tudinal section, through a staminate 
catkin of Comptonia asplenifolia X 10, 
showing catkin axis (ax), anther-lobe 
(a), and bract (b). 
