188 COMPOUND ORGANS OP PLANTS. 



as the former or the latter only are found within the floral 

 envelopes. 



When the stamens and pistils are in separate flowers on the 

 same plant, as in the castor-oil plant, (Ricinus,) and Indian 

 corn, (Zea mays,) the flowers are monoecious, (^0*05 one, oixtov 

 habitation.) When the staminate flowers are on one plant and the 

 pistillate flowers on another, the flowers are dioecious (Stj twice,) 

 as in the nettle and hop ; and when the same plant developes 

 both unisexual and hermaphrodite flowers, they are polyga- 

 mous {TtoTjvs many, ya/ioj marriage,) as in the maple and Euphor- 

 bia. In the marginal flowers of Hydrangea arborescens, and 

 Viburnum opulus, the Snow-ball tree, the essential organs, the 

 stamens and pistils, are entirely suppressed ; these flowers are 

 therefore necessarily sterile. 



The following diagrams will illustrate the several stages in 

 the suppression of the floral organs of Phanerogamous plants, 

 until we arrive at their minimum reduction, when any farther 

 suppression would render the production of an embryo or seed 

 impossible. 



Fig. 83. 



Fig. 83, is a representation of the flower of the Saururus 

 cernuus or Lizaid's tail. The flowers of this plant are perfect, 

 and are developed in racemes or spikes, but destitute of all 

 floral envelopes, a simple scale or bract supplying their place. 



