270 PHARMACEUTICAL BOTANY 
coloring they are together called the perianth. The purpose of 
these envelopes is to protect the reproductive organs within, and 
also to aid in the fertilization of the flower, as their bright colors, 
fragrance and saccharine secretions serve to attract pollen-carry- 
ing insects. 
When the petals are not united with each other, the corolla is 
said to be CHORIPETALOUS, APOPETALOUS or POLYPETALOUS. 
ca 
Fic. 190.—Sour Cherry (Prunus cerasus). Median longitudinal section of flower. 
Note the perigynous insertion of the sepals, petals and stamens. The ovary is 
superior. (After Robbins.) 
When more or less united into a tubular structure, it is Gamo- me 
PETALOUS, often called SYNPETALOUS. 
ForMS OF THE COROLLA AND PERIANTH.—When the distinct _ 
petals are four in number, and arranged in the form of a cross, 
the corolla is called Cruciform. Example: Mustard and other e 
plants belonging to the family Cruciferz. : 
The Papilionaceous corolla is so called because of a taseied 
resemblance to a butterfly. The irregularity in this form i is — 
