Fertilization of Flowers. 



purple and white stripes act as guide boards to direct its way to the 

 bottom of the tube. Suppose it to be a staminate plant. The body 

 of the insect is soon dusted with pollen. It now turns to retire and 

 naturally walks up the central column, the sterile prolongation of the 

 spadix, which aids its retreat and safely conducts it to the open door 

 whence its flight to and descent into a pistillate flower is an easy mat- 

 ter. There its load of pollen is soon brushed upon the receptive stig- 

 mas while it is feeding on the food prepared for it. In the case of the 

 monoecious flowers there is a reason for the relative position of the 

 staminate and pistillate flowers. The in-, ct lu\ing partaken of the 

 nectar turns to climb the column toward the place of exit, and in so 

 doing passes over the stamens and becomes dusted with the pollen just 

 before leaving this plant to visit another. The roof-like summit of 

 the spatho serves well to prevent rain from heating down the pollen to 

 the stigmas below, in monoecious plants and from spoiling the nectar 



There are many flowers whose structure is such that at first sight it 

 appears to be favorable to self-fertilization, but when more closely 

 observed it is found to be really designed to secure cross-fertilization. 



In our species of Kalmia, which genus includes the mountain laurel 

 or calico bush and the sheep laurel, the filaments of the stamens are 

 elastic and the anthers are imprisoned each in a small cavity or de- 

 pression in the cup-shaped corolla. As the corolla expands the upper 

 part of the stamen is drawn Lack as far as possible from the center of 

 the flower and the filament is held in a high state of tension. If now 

 the flowers are subjected to any sudden jar such as may be produced 

 by a blast of wind or a bird settling on the branches, the anthers are 

 liberated and the elasticity of the filaments throws them with a sudden 

 jerk toward the opposite side of the flower, and the pollen is dashed 

 out and flies in small cloud-like masses in every direction. This looks 

 like a contrivance for self-fertilization. But now suppose an insect 

 settles on the flowers. By its motions it liberates the anthers and the 

 pollen is freely dashed over its body whereon it is carried to the flowers 

 of neighboring plants and cross-fertilization is secured. 



The mode of fertilization of some of our lobelias has been investi- 

 gated by Professor W. Trelease. In these flowers the anthers are 

 united very much as they are in the flowers of the Compositae. They 

 form a kind of tube whose apical aperture is closed by a tuft of hairs 

 until the pollen is mature. The style is at first nearly equal in length 

 to the stamens and its two-lobed stigma is inclosed in the anther tube. 

 Just below the stigma it is girt by a circle of radiating hairs which 



