Chap. IV. OXALIS^ OTHER SPECIES OP. 179 



chased under the name of 0. Bowii (but I have some 

 doubts whether it was rightly named), and fertilised 

 many flowers with their own two kinds of pollen, 

 which differ in diameter in the usual manner, but 

 never got a single seed. On the other hand, Hil- 

 debrand says that the short-styled form of 0. Deppei, 

 growing by itself, yields plenty of seed; but it is not 

 positively known that this species is heterostyled ; and 

 the pollen-grains from the two sets of anthers do not 

 differ in diameter. 



Some facts communicated to me by Fritz Miiller 

 afford excellent evidence of the utter sterility of one 

 of the forms of certain trimorphic species of Oxalis, 

 when growing isolated. He has seen in St. Catharina, 

 in Brazil, a large field of young sugar-cane, many 

 acres in extent, covered with the red blossoms of one 

 form alone, and these did not produce a single seed. 

 His own land is covered with the short-styled form of 

 a white-flowered trimorphic species, and this is equally 

 sterile; but when the three forms were planted near 

 together in his garden, they seeded freely. With two 

 other trimorphic species he finds that isolated plants 

 are always sterile. 



Fritz Miiller formerly believed that a species of 

 Gxalis, which is so abundant in St. Catharina that it 

 borders the roads for miles, was dimorphic instead of 

 trimorphic. Although the pistils and stamens vary 

 greatly in length, as was evident in some specimens 

 sent to me, yet the plants can be divided into two 

 sets, according to the lengths of these organs. A 

 large proportion of the anthers are of a white colour 

 and quite destitute of pollen; others which are pale 

 yellow contain many bad with some good grains; and 

 others again which are bright yellow have apparently 

 sound pollen; but he has never succeeded in finding 



