FLOWERS. 93 



If all the organs of which the flower is composed are present 

 in the powder then the number of elements that may be made 

 available for its determination is largely increased. In addition 

 to the pollen grains the cellular tissue of the anthers will be 

 present. The calyx almost always contains sclerenchymatous 

 elements, and the receptacle often exhibits structural pecu- 

 liarities that are of distinct value, as is the case with insect 

 flowers. The powders of aromatic flowers and flowering tops are 

 generally characterised by the presence of particular oil-glands 

 which render them comparatively easy to recognise. 



In addition to the flower itself flowering tops usually con- 

 tain bracts, peduncles, and portions of the flowering stem. 

 Such drugs exhibit when powdered a distinct increase in the 

 debris of fibro-vascular bundles, whilst in some cases particular 

 sclerenchymatous cells may be introduced, as such elements 

 are frequently present in considerable number in the stem and 

 its branches. The presence of palisade tissue generally indi- 

 cates the presence of leaves or leafy organs. 



