414 RUSSELL— A COMPARATIVE STUDY OE 



Limnanthes Donglasii: — the petals are a more primitive color, white 

 or whitish yellow, still much exceeding the sepals, yet not so large as in 

 Limnanthes rosea (sepals 5-6 mm., petals 10-15 mm.). Limnanthes 

 versicolor is about as L. Douglasil and is probably a hairy form of L. 

 Douglasii. L. alba also has petals exceeding the sepals (sepals 6-8 mm., 

 petals 10-15 mm.). 



Limnanthes pumila forms a transition type from those whose petals 

 exceed the sepals, to those with sepals exceeding the petals. It is given 

 as having petals "scarcely exceeding the sepals. " The petals too in this 

 more nearly approach the oblong type found in forms with smaller petals. 



Limnanthes floccosa comes next with "oblong cuneate petals, not 

 exceeding the sepals." 



In the tetramerous Limnanthes Macounii the petals equal the sepals. 

 This forms a valuable transition species, being reduced both in the num- 

 ber and size of the parts (petals 3-4 mm., sepals 3-4 mm.). 



In Floerkea proserpinacoides the petals are oblong and about the 

 length of the sepals (sepals 3 mm.; petals 1-5 mm.), flowers trimerous, 

 valvate in aestivation. 



In Floerkea occidentaUs the petals and sepals are reduced in size 

 (petals 1 mm., sepals 2-3 mm. long). The petals are valvate in aestiva- 

 tion. This distinction is not important since it would be impossible from 

 the size of the petals in Floerkea to have a convolute aestivation. The 

 petals are so small and reduced that they do not overlap. 



The two species of Floerkea are distinguished by Rydberg (1) on 

 account of the different lengths of peduncles, thus: — 



Peduncles longer than the petioles — F. occidentaUs. 



Peduncles rarely equalling the petioles — F. proserpinacoides. 



This is not a difference to be depended on, for F. proserpinacoides 

 does show the peduncles longer than the petioles. The plants exhibiting 

 this were collected in different localities around Philadelphia. Rydberg 

 and others who accept F. occidentaUs do not report it from the region 

 about Philadelphia. 



From the anatomy of these two forms just described, F. proserpina- 

 coides and L. Douglasii, it will be seen that they show a remarkable 

 similarity in structure. Their correspondence in such minute details 

 as the thickenings upon the epidermal cells of the carpellary walls, in 

 the possession by both of the fused integuments about the ovule, which 

 store food in the form of starch, of the subsequent absorption of the 

 starch in the growth of the embryo, and the flattening of the empty cells 

 by the enlarged embryo in the mature seed; by the presence upon the 



