132 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. 



The several points of difference in structure between 

 the two forms of Faramea are highly remarkable. 

 Until within the recent period, if any one had been 

 shown two plants which differed in a uniform manner 

 in the length of their stamens and pistils, in the 

 form of their stigmas, in the manner of dehiscence 

 and slightly in the size of their anthers, and to an 

 extraordinary degree in the diameter and structure of 

 their pollen-grains, he would have declared it impos- 

 sible that the two could have belonged to one and the 

 same species. 



SUTERIA (species unnamed in the herbarium at Kew) 

 (RUBIACE.E). 



I owe to the kindness of Fritz Miiller dried flowers of 

 this plant from St. Catharina, in Brazil. In the long-styled 

 form the stigma stands in the mouth of the corolla, above 

 the anthers, which latter are enclosed within the tube, but 

 only a short way down. In the short-styled form the an- 

 thers are placed in the mouth of the corolla above the 

 stigma, which occupies the same position as the anthers in 

 the other form, being seated only a short way down the 

 tube. Therefore the pistil of the long-styled form does not 

 exceed in length that of the short-styled in nearly so great 

 a degree as in many other Rubiaceae. Nevertheless there 

 is a considerable difference in the size of the pollen-grains 

 in the two forms; for, as Fritz Miiller informs me, those 

 of the short-styled are to those of the long-styled as 100 

 to 75 in diameter. 



HOUSTONIA COZRULEA (RUBIACE^E). 



Professor Asa Gray has been so kind as to send me an 

 abstract of some observations made by Dr. Rothrock on 

 this plant. The pistil is exserted in the one form and the 

 stamens in the other, as has long been observed. The stig- 

 mas of the long-styled form are shorter, stouter, and far 

 more hispid than in the other form. The stigmatic hairs 

 or papillae on the former are .04 mm., and on the latter 

 only .023 mm. in length. In the short-styled form the an- 



