196 ANNA HALL RAITT 



Later in June yellow flowers appear which are like the ordi- 

 nary open flowers except that they bear no stamens and pistils. 

 At least this condition occurred in the plants studied in the sum- 

 mer of 1911. These sterile flowers persisted for only a short 

 time, and before they had disappeared, early in July, the ordi- 

 nary fertile flowers appeared. The first of October found the 

 plants full of seed capsules in all stages, with still a few flowers 

 among them. The flower is pale yellow, and those which I col- 

 lected were not spotted. The mature seed capsule is about 2.5 

 cm. or 3 cm. long, and five-lobed, but very rarely contains more 

 than three seeds. By the time the seeds are mature, the pla- 

 centa is a mere thread extending through the length of the capsule. 



DEVELOPMENT OF THE FLOWER 



The development of the flower begins with the appearance of 

 the saccate sepal, which covers the young bud like a cap through- 

 out its development (fig. 1, A). Just within this sepal and the 

 other two which closely follow it, a circle of small lobes indicate 

 the beginning of the petals. Not until the petals have grown 

 sufficiently long to over-arch the tip do the stamens begin to 

 appear (fig. 1, B). The central space fails to show any sign of 

 a pistil until the anther tissue is beginning to be differentiated, 

 when a column arises from the flower axis (fig. 1, C). This col- 

 umn soon becomes dome-shaped and a section across it shows 

 the five small cavities (fig. 1, F). When the pollen mother cells 

 are beginning to form, the ovules begin to develop from the pla- 

 centa (fig. 1, C). 



THE OVULE 



The ovules are produced on the axial placenta and arise in 

 the usual way, forming at first a top-shaped protuberance. The 

 archesporial cell does not appear before the protuberance is well 

 started. It is probably a single cell of the hypodermis, though 

 it is difficult to isolate, but the primary sporogenous and pri- 

 mary'' parietal cells appear clearly in the usual position (fig. 1, 

 D and E). 



