Feb., 1918] Sexual Dimorphism 125 



Menispermum canadense L. Diecious. The carpellate flower has 

 about twelve vestigial stamens; the staminate flower has no vestiges. 



Sassafras sassafras (L.) Karst. Diecious. The staminate flower 

 has a vestij^ial carpel: the carpellate flower has six staminodes. 



Zanthoxylum americanum Mill. Usually diecious. The staminate 

 flower has prominent vestigial carpels, the carpellate flower sometimes 

 has minute vestigial stamens. 



Ptelia trifoliata L. Imperfectly monosporangiate and imprefectly 

 monecious. The staminate flower has a prominent imperfect gynecium; 

 the car])ellate flower has five vestigial stamens. 



Ailanthus glandulosa Desf. Diecious. The carpellate flower has ten 

 prominent staminodes; the staminate flower has a prominent vestigial 

 gynecium of five carpels. 



Napea dioica L. Diecious. The carpellate flower has a vestigial 

 stamen column; the staminate flower has no vestige. 



Rumex acetosella L. Diecious. The staminate flower has a small 

 vestigial gynecium with three minute stigmas ; the carpellate flower has 

 no vestiges. 



Aruncus aruncus (L.) Karst. Diecious. The carpellate flower has 

 vestigial stamens; the staminate flower has three vestigial carpels. 



Gymnocladus dioica (L.) Koch. Diecious. The carpellate flower has 

 ten large staminodes; the staminate flower has a vestigial carpel. 



Acer negundo L. Apparently strictly diecious with no vestiges of 

 the opposite organs. In the lower species of Maples the trees are 

 imperfectly diecious and the flowers have very prominent vestiges of 

 the opposite organs. 



Morus rubra L. Diecious. Staminate flowers with a vestigial 

 gynecium; carpellate flowers without vestiges. Often there are 

 staminate and carpellate catkins on the same tree; sometimes there 

 are carpellate and staminate flowers on the same catkin; some- 

 times a carpellate catkin may contain a single staminate flower. 



Cannabis sativa L. Diecious; but the plants are of various degrees; 

 some carpellate plants may have stamens and staminate plants may 

 have carpels. 



Populus deltoides Marsh. Apparently strictly diecious, as also 

 some willows, but there are intermediate willows, occasionally. 



Cucumis sativus L. Monecious. The carpellate flower has three 

 vestigial stamens; the staminate flower has a tricarpellate, vestigial 

 gynecium. 



Diospyros virginiana L. Usually diecious. Carpellate flower with 

 vestigial stamens; staminate flower with a large vestigial gynecium. 



Fraxinus americana L. Apparently strictly diecious. Various 

 species of Fraxinus present gradations from bisporangiate, conspicuous 

 flowers to diecious flowers with loss of perianth and nectar glands. 



Ambrosia trifida L. Monecious. The staminate flower has a 

 vestigial gynecium; the carpellate flower shows no vestiges of stamens. 



