66 PART I. — ORGANOGRAPHY. 



paring them with related plants, from a study of the development 

 of their flowers, from the observed facts of variation in plants, 

 and from the study of monstrous or abnormal forms of flowers 

 that occasionally make their appearance. Monstrous flowers of 

 the Lady's-slipper (Cypripedium spectabile) have been found 

 that were almost perfectly regular and symmetrical. In the 

 frontispiece is shown such a flower growing on the same stem 

 as one which has the ordinary form of this species. The selec- 

 tion exercised by insects in visiting flowers for their nectar and 

 pollen, in conjunction with the tendency which all flowers have 

 to vary, has curiously enough been proved to be one important 

 agency in producing irregular and unsymmetrical flowers. (See 

 the subject of Pollination). 



The more important deviations from the typical form of the 

 flower may be classified and described as follows : 



(i) Deviations due to a Deficiency of Parts. A flower may 

 be defective or incomplete in almost any degree. Only a portion 

 of a single whorl may be absent, or one or more entire whorls 

 may be wanting. There are flowers so defective as to consist only 

 of a single stamen, or of a single pistil, as in the little Wolffia. 



A flower that lacks one of the floral envelopes is called 

 monochlamydeous ; one that is destitute of both calyx and corolla, 

 achlamydeous, or naked ; if it has pistils, but is destitute of the 

 staminal whorl or andrcecium, it is called pistillate, or female ; if 

 it possesses stamens, but not pistils, it is described as staminate, 

 or male ; and if it be destitute of both, it is called neuter. Such 

 showy neutral flowers are seen in the border of the cymes of the 

 wild Hydrangea and Cranberry-tree. 



Some plants, as the Begonias, Castor-oil Plant and Maize, 

 bear two kinds of flowers, staminate and pistillate, on the same 

 plant. Such a plant is described as mouarius. In the case of 

 some others the staminate and pistillate flowers are borne by 

 different plants of the same species ; this is true of Sassafras, 

 many Willows, the Tree of Heaven, etc. Such plants are dioecious. 

 The Maple is an example of a tree which produces staminate, 

 pistillate and hermaphrodite flowers all on the same tree. Such 

 a plant is termed polygamous. 



(2) Deviations due to a Rodundancy of Parts. This is scarcely 

 less common, and may apply to any of the floral organs. So-called 



