130 Shmu — Structm'e of the Floivers in 



ject as a feathery tuft when the flower is open. The two pos- 

 terior petals are about the same length, but are much 

 narrower, lanceolate, and fused below with the hooded petal 

 and stamen. The petals are composed of elongated, spongy, 

 thin-walled cells, and stomata have never been found on 

 them. 



Corolla. — B. The Aerial Cleistogamic Flower. The anterior 

 petals are tolerably well developed, nearly as long as the 

 sepals and more or less fashioned into a hood, partly enclos- 

 ing the stamens and style. The posterior petals, rarely want- 

 ing, are generally present as small processes from the tube 

 formed by the anterior petals and stamens. Sometimes they 

 are more developed and appear as small lanceolate petals. 



Coi'olla. — C. The Subterranean Cleistogamic Flower. Here 

 the corolla is reduced to a single petal, the posterior ones 

 having quite disappeared, while the anterior alone persists. 

 The hood and its fimbriated process are also lacking. The 

 solitary petal at the time of pollination has the form of a blunt 

 process, about as long as the ovary, viz., — i ^ millimeters. 



Andrcecium. — A. The Chasmogamic Flower. The stamens 

 are nearly equal, and are placed with the style close under the 

 hood of the anterior petal. The superficial cell-walls of the 

 anthers have stellate thickenings which no doubt assist in 

 dehiscence. From one to two hundred microspores are 

 formed in each anther. 



The microspores undergo a great increase in size at the 

 time of flowering. Immediately before the flower opens they 

 are relatively small, with exceedingly thick walls, but they 

 increase several times in size during the maturing of the 

 flower. This seemed a remarkable peculiarity, but numerous 

 measurements of these and exact drawings with the camera 

 lucida, leave no doubt as to the fact. In Plate XVII, Figs. 4-7 is 

 shown a series, taken from successively older blossoms on the 

 same axis, and drawn under the camera. The relative thick- 



