XIV PEEFACE. 



Urban in Linnsea, B. vii. p. 621. Mr. Meehan (Bull. 

 Torrey Bot. Club, vol. vi. p. 189) bas endeavoured 

 to tbrow doubts on my observations on the sterility of 

 the forms of L. pererkie when fertilised with their own- 

 form pollen, because a plant from Colorado yielded 

 seed, when growing by itself ; but as might have been 

 expected, and as is sufficiently clear from the remarks 

 of a well-known reviewer in the American Journal of 

 Science, Mr. Meehan mistook L. Leivisii, which is not 

 heterostyled, for L. perenne. 



In the Boraginese, Lithospermwm, canescens differs, 

 according to Mr, Erwin F. Smith {Bot. Gazette, United 

 States, vol. iv. 1879, p. 168), from the heterostyled 

 species of the same genus by occasionally presenting 

 a mid-styled form, which has a short pistil like that 

 of the short-styled, and short stamens like those of the 

 long-styled form. All the forms seem variable, and 

 the whole case requires further investigation. 



Mr. Alex. S. Wilson informs me that on comparing 

 the pollen-grains from a long-styled plant of Erythrgea 

 eeniawrimn with those from some short-styled plants 

 from the island of Arran, they differed in size and 

 shape, as in the case of the undoubtedly heterostyled 

 Menyanthes trifoliata, a member of the same family of 

 the Gentianeee. I had myself formerly observed that 

 the flowers on different plants differed much in 

 structure, but could not make out that they presented 

 two distinct forms. 



The Eubiacese contain many more heterostyled 

 plants than any other family, and several additional 

 cases can now be added. Mr. C. B. Clarke has been 

 so kind as to send me sketches made in India of two 

 extremely distinct forms of Adenosacme longifolia. He 

 remarks " that the peculiarity of the case is not the 

 difference in the length of the style and stamens 



