MANUAL OF NATURE STUDY. 
149 
ready for action. The stigma and pollen must rip¬ 
en at the same time, else self-fertilization can not 
occur. See Gray’s Structural Botany, pages 216— 
242. 
In regard to the coalescence of the parts of the 
floral envelope, it will be well to require seventh 
grade pupils to learn the botanical names. When 
the whorl of petals is more or less united, the cor¬ 
olla is called gamopetalous, a name signifying grown 
together. When not united, or when the petals are 
separate to the very base, the corolla is called 
polypetalous , a name signifying many separate 
petals. 
When the outer whorl of the floral envelope is 
united throughout any part of the sepals, above the 
point of insertion, the flower is called gamosepalous. 
When the sepals are separate to the very point of 
insertion the flower is called polysepalous . 
The expanded portion of a petal, or that which 
answers to the blade of a leaf, is called lamina or 
blade; that which answers to the petiole of a leaf, 
or filament of a stamen, is called claw or unguis. 
When this claw is absent, we may say that the pet¬ 
al is sessile. 
The lower part of a gamopetalous corolla is called 
a tube , if the sides are nearly parallel or at least 
not too spreading. For example, the lower part of 
the morning glory blossom is a tube . 
