Chap. III. POLYGONUM FAGOPYRUM. HI 



all of them, when protected from the access of insects, 

 yielded plenty of seeds. Again, from statements made by 

 Vaucher, and from a hasty inspection, I thought at first 

 that the allied Anchusa arvensis and Echium vulgare were 

 heterostyled, but soon saw my error. From information 

 given me, I examined dried flowers of another member of 

 the Boragineae, Arnehia hispidissima, collected from sev- 

 eral sites, and though the corolla, together with the in- 

 cluded organs, differed much in length, there was no sign 

 of heterostylism. 



Polygonum fagoptkum (PoLTGONACE.ffi). 



Hildebrand has shown that this plant, the common 

 Buck- wheat, is heterostyled.* In the long-styled form 

 (Fig. 7), the three stigmas project considerably above 

 the eight short stamens, and stand on a level with the 

 anthers of the eight long stamens in the short-styled 

 form; and so it is conversely with the stigmas and 

 stamens of this latter form. I could perceive no differ- 

 ence in the structure of the stigmas in the two forms. 

 The pollen-grains of the short-styled form are to those 

 of the long-styled as 100 to 82 in diameter. This plant 

 is therefore without doubt heterostyled. 



I experimented only in an imperfect manner on the 

 relative fertility of the two forms. Short-styled flowers 

 were dragged several times over two heads of flowers 

 on long-styled plants, protected under a net, which were 

 thus legitimately, though not fully, fertilised. They 

 produced 32 seeds, or 11 per flower-head. 



Three flower-heads on long-styled plants received 

 pollen in the same manner from other long-styled plants, 

 and were thus illegitimately fertilised. They produced 

 14 seeds, or only 4.66 per flower-head. 



Two flower-heads on short-styled plants received 

 pollen in like manner from long-styled flowers, and 



* 'Die Geschlechter-Vertheilung,' &o., 1867, p. 34. 



