Chap. in. POLYGONUM FAGOPYRUH. Ill 



have stamens somewhat arrested in development, with very 

 little pollen in their anthers ; and in such flowers the stigma 

 projects above the anthers, whilst generally it stands below and 

 sometimes on a level with them. I could detect no difference 

 in the size of the pollen-grain or in the structure of the stigma 

 in the plants which differed most in the above respects ; and 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 

 Anchuna arvensis and Echium vulgai e were heterostyled, but soon 

 saw my error. From information given me, I examined dried 

 flowers of another member of the Boragineae, Arnebia hispidis- 

 sima, collected from several sites, and though the corolla, to- 

 gether with the included organs, differed much in length, there 

 was no sign of heterostylism. 



Polygonum fagopyhum (PoLYGONACEiE). 



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, ferti- 

 lised. They produced 22 seeds, or 11 per flower-head. 



Three flower-heads on long-styled plants received 



* ' Die Gcschlochtor-Veitlieilung,' &o., 1867, p. 34. 



