130 Shaw—Structure of the Flowers 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 Aérial 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. 
Corolla.—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..—1% millimeters. 
Andracium.—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- 
