FLOERKEA PROSERPIXACOIDES AND ALLIES 415 



tip of the cotyledon in both of a water stomatic area, is striking. Simi- 

 larity of structure in all of these parts indicates surely an extremely close 

 relation between these two plants placed in separate genera. In com- 

 paring the anatomical features, it seems reasonable to look upon Floerkea 

 as a type of plant evolved from Limnanthes by reduction. Thus: the 

 stem shows a similar but reduced structure to that of Limnanthes; the 

 glands upon the stamens in Floerkea are not so large as are those of 

 Limnanthes, nor are the cells so rich in protoplasm. The hairs upon the 

 base of the petals in Floerkea are shorter than those in Limnanthes, where 

 they probably act as protecting hairs about the nectaries or glands at 

 the base of the stamens between the petals. In Floerkea these probably 

 do not function as in Limnanthes, since the petals are much reduced in 

 size, and the hairs are too short to reach out and protect the gland at the 

 base of the stamens. In the number and size of flower parts Floerkea 

 shows reduction from Limnanthes as has been already traced. The 

 geographical distribution already noted also suggests a continuous rela- 

 tion and close affinity between the pentamerous, tetramerous and tri- 

 merous forms in the two genera. 



Until a complete series is made out, however, between the pentamer- 

 ous forms with epigeal cotyledons and the trimerous forms with h>^ogeal 

 cotyledons the two genera wdll have to remain distinct as Robert Brown 

 \dewed them. 



The writer takes this opportunity to acknowledge her indebtedness 

 to Dr. John M. Macfarlane for his advice and assistance in preparing 

 this paper. 



Summary 



Two plants were studied microscopically and macroscopically as 

 representing each one of the two genera of the family Limnanthaceae — 

 Floerkea proserpinacoides and Limnanthes Doiiglasii. 



In the anatomical features of the root, stem, leaf, flower and fruit, 

 these two forms show a striking similarity of structure, Floerkea proser- 

 pinacoides indicating by its reduced members that it is a form derived 

 from Limnanthes by reduction. In its present distribution, the family 

 Limnanthes is represented in the west by species of Limnanthes, and in 

 the east and west by Floerkea. Transition types are represented by 

 various species of Limnanthes ranging from large attractive pentamerous 

 types through a lesser tetramerous species to the trimerous flower types 

 characteristic of the genus Floerkea. Since the genus Floerkea overlaps 

 the distribution areas of the pentamerous and tetramerous forms it is 

 likely to be a t>^e evolved from them which worked its way through 



