CHAPTER VII 
FLOWERS 
The histological structure of flowers is readily seen in the 
powder; therefore, in studying flowers, it is not necessary to 
section the various parts. Each part of the flower should be 
isolated and powdered separately and each separated part 
studied. In each case the powders will contain surface, cross-, 
and radial sections of the parts powdered. While studying 
flowers, special attention should be given to the pollen grains, 
to the papillz of the petals, to the papille of the stigma, and, 
in certain flowers, to the style tissue. In the composite flowers 
special attention should also be given to the involucre scales, 
to the scales of receptacle, and, when present, to the pappus. 
In addition, attention must be given to secretion cavities, as 
in cloves. . 
POLLEN GRAINS 
Pollen grains are one of the most characteristic elements 
found in powdered flowers, because they are so small that they 
are not broken up when the drug is milled. 
The two principal groups of pollen grains are, first, those with 
non-spiny walls (Plate 113); and, secondly, those with spiny 
walls (Plate 114), as shown in the two charts. 
In lavender flowers the pollen grains have six constrictions 
of the outer wall. This wall is slightly striated and the cell 
contents are granular. 
In clover flowers the pollen grains are mostly rounded in 
outline, the wall is uniformly thickened, and cell contents are 
coarsely granular. 
In belladonna flowers the pollen grains terminate in three 
blunt points. 
In Spanish saffron the pollen grains are spherical and the 
cell contents are granular. 
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