CHAP. III. RUBIACE^E. 135 



are as 100 to 80 in diameter, compared with those from the 

 long-styled form. 



CINCHONA MICRANTHA (EUSTACES). 



Dried specimens of both forms of this plant were sent 

 me from Kew.* In the long-styled form the apex of the 

 stigma stands just beneath the bases of the hairy lobes of 

 the corolla; whilst the summits of the anthers are seated 

 about halfway down the tube. The pistil is in length as 

 100 to 38 to that of the short-styled form. In the latter 

 the anthers occupy the same position as the stigma of the 

 other form, and they are considerably longer than those of 

 the long-styled form. As the summit of the stigma in the 

 short-styled form stands beneath the bases of the anthers, 

 which are seated halfway down the corolla, the style has 

 been extremely shortened in this form; its length to that 

 of the long-styled being, in the specimens examined, only 

 as 5.3 to 100 ! The stigma, also, in the short-styled form is 

 very much shorter than that in the long-styled, in the ratio 

 of 57 to 100. The pollen-grains from the short-styled 

 flowers, after having been soaked in water, were rather 

 larger in about the ratio of 100 to 91 than those from 

 the long-styled flowers, and they were more triangular, 

 with the angles more prominent. As all the grains from 

 the short-styled flowers were thus characterised, and as 

 they had been left in water for three days, I am convinced 

 that this difference in shape in the two sets of grains can- 

 not be accounted for by unequal distension with water. 



Besides the several Rubiaceous genera already men- 

 tioned, Fritz Miiller informs me that two or three species 

 of Psychotria and Rudgea eriantha, natives of St. Catha- 

 rina, in Brazil, are heterostyled, as is Manettia bicolor. I 

 may add that I formerly fertilised with their own pollen 

 several flowers on a plant of this latter species in my hot- 

 house, but they did not set a single fruit. From Wight 

 and Arnott's description, there seems to be little doubt that 

 Knoxia in India is heterostyled; and Asa Gray is con- 

 vinced that this is the case with Diodia and Spermacoce 



* My attention was called to this given by Mr. Markham in his 

 plant by a drawing copied from 'Travels in Peru,' p. 539. 

 Howard's 'Quinologia,' Tab. 3, 



