126 Shaw — Structure of the Flowers in 



insf beneath the soil. In the axils of their small bracts are 

 white or pinkish protuberances, the subterranean flowers. At 

 the time of pollination they are about one millimeter in length, 

 but after pollination they rapidly enlarge, and in a surpris- 

 ingly brief period assume the proportions of seed capsules. 

 Thus, although such flowers appear in the Wood's Holl 

 neighborhood from the fifteenth to the twentieth of June, about 

 the same time with evident flowers, they ripen seed sooner. 

 As early as July 4 seeds from these cleistogamic flowers may 

 be found. Seeds are also produced much more abundantly 

 from these than from the chasmogamic flowers. 



(3) Aerial Cleistogamic or Intermediate Flowers. 



Mention has already been made of the fact that another 

 and unrecognized type of flower exists in this plant. In July, 

 after both the evident and the underground cleistogamic 

 flowers have been developing for a time, aerial branches may 

 be seen bending downward. These bear, in addition to small 

 leaves, little green tubercular bodies which are, in fact, another 

 set of microscopic flowers. They are produced in such 

 abundance, too, that small though they are, it is remarkable 

 that they have never been clearly recognized and described. 



They are considerably larger than the underground type 

 and bright green, while all parts of the flower are more devel- 

 oped. Their development is generally associated with geo- 

 tropic tendencies on the part of the shoot bearing them. It 

 is especially striking to note that a leafy shoot, after having 

 grown upwards and perhaps borne evident flowers, may begin 

 to develop these small closed ones, and in so doing to bend 

 over at its tip to pursue the opposite course. At Wood's Holl 

 experiments were tried of digging up sods of plants bearing 

 geotropic shoots and inverting them. In a day or two the 

 tips were seen to show reversed curvature, thus reasserting 

 their geotropic tendencies. 



