POLYGONACEAE 339 



a little or not at all beyond it, and the stigmas being situated beneath them : automatic 

 self-pollination is therefore inevitable, and, in fact, the only possible means of fertiliza- 

 tion, for towards the end of dehiscence the perianth leaves generally close tightly 

 round the anthers again. The flowers are sometimes gynomonoecious and andro- 

 dioecious. 



2458. R. alpinus L. (Schulz, op. cit., II, p. 154; Kerner, 'Nat. Hist. PI.,' 

 Eng. Ed. I, II, 143, 295, 298, 312.) — In this species the anthers first dehisce. 

 During this stage the three stigmas mature, and finally project so far beyond the 

 flower that they are easily dusted with pollen from younger blossoms. This is 

 facilitated by the fact that during dehiscence the flower stalks are flexible, and the 

 flowers therefore easily swayed by the wind. After dehiscence, however, the stalks 

 become rather stiff, so that during the female stage the flowers are only slightly 

 movable. 



The flowers are sometimes gynomonoecious and andromonoecious. Female 

 ones are generally considerably smaller than those which are hermaphrodite or male. 



Kerner states that in this species, as in R. sanguineus and R. obtusifohus, 

 the female and male flowers predominate in the inflorescences, with only a few 

 hermaphrodite ones. The stigmas are receptive some time before the anthers of 

 flowers on the same stock have dehisced. Crossing by means of wind must therefore 

 be effected. Geitonogamy is also possible, for though the stigmas of the hermaphro- 

 dite flowers are at first hidden, they are exposed by the bending back of the perianth 

 lobes and pollen from adjacent younger blossoms can fall on them. 



2459. R. longifolius H. B. et K. (= R. domesticus Hartm.). Ekstam says that 

 this species possesses first protogynous, then homogamous hermaphrodite flowers, 

 which are pollinated by wind : they are sometimes gynomonoecious. 



2460. R. scutatus L. (Schulz, op. cit., II, pp. 154-5.) — The hermaphrodite 

 flowers of this species are markedly protandrous. The stigmas generally remain 

 unreceptive until after the anthers have dehisced, thus apparently excluding self- 

 pollination. Anemophily is, however, easily effected, for the large, brush-shaped 

 stigmas are well exposed to currents of air. Gynomonoecism and androdioecism 

 sometimes occur. 



2461. R. Acetosella L. (H. Hoffmann. Bot. Ztg., Leipzig, xliii, 1885; 

 IMacLeod, Bot. Jaavb. Dodonaea, Ghent, vi, 1894, p. 140; Schulz, op. cit., II, 

 p. 198.) — Lindman states that the hermaphrodite flowers of this species on the 

 Dovrefjeld are first protogynous, then homogamous ; and that gynomonoecious as 

 well as hermaphrodite flowers occur there. Schulz says that the flowers are usually 

 dioecious, with both sexes equally numerous, much more rarely gynomonoecious or 

 hermaphrodite. 



Appel tells me in a letter that he observed purely male stocks. 



2462. R. Acetosa L. (Schulz, op. cit., II, p. 198; Knuth, 'Beitrage.') — As 

 the preceding species. 



Visitors. — Knuth (Gliicksburg, 30. 7. '96) observed numerous honey-bees, 

 eagerly skg., and flying steadily from flower to flower, their entire bodies grey with 

 pollen. 



2463. R. montanus Desf {~ R. arifolius All.). (Schulz, op. cit., II, p. 198.)— 



