24 INTRODUCTION 
in a fresh flower with a viscid liquid to which 
the pollen grains readily adhere. 
EVENING PRIMROSE 
The blossoms of this plant generally first open 
in the evening. The process may be readily seen 
by a little patient watching: the tips of the sepal- 
lobes spread apart and soon afterward the petals 
expand. At this time the flower is fully open 
