22 ANGIOSPERMAE—DICOTYLEDONES 



Vanheffen (Abromeit, ' Bot. Ergeb. v. Drygalski's Gronlandsexped./ p. 30) 

 observed this species in partially flooded places in Greenland. The leaves projected 

 beyond the small flowers. 



55. R. paucistamineus Tausch, var. eradicata Laestad. (=R. confervoides 

 Fries, in Lange's ' Consp. flor. groenl.').— Vanhoffen (Abromeit, op. cit., pp. 29-30) 

 found this species with mature fruits in ponds in Greenland. 



56. R. pygmaeus Wg. — Ekstam states that the flowers are homogamous in 

 the Scandinavian highlands. Their diameter there is 7 or 4 mm., and on Nova 

 Zemlia 5-10 mm. The stigmas, especially in the small flowers, stand at the same 

 level as the anthers, so that automatic self-pollination must take place, and this 

 is effective in Scandinavia and Nova Zemlia ; also in other parts of the Arctic 

 regions, as Warming has shown. 



Andersson and Hesselman (op. cit., p. 48) say that the species flowers in 

 Spitzbergen from the end of July to the middle of August, and is in blossom on 

 Beeren Island by the middle of June. The fruits mature early, many of them 

 being ripe at the beginning of August, or later. Little pollen is produced, but this 

 develops normally. Self-pollination is brought about by contact of the dehisced 

 anthers with the stigmas of the lower carpels. According to Ekstam (' Bliitenbiol. 

 Beob. a. Spitzbergen,' pp. 22-3), the flowers are 5-8 mm. broad and non-fragrant. 

 They are feebly protandrous, all the anthers having as a rule dehisced before the 

 stigmas have completely matured. 



57. R. Flammula L. (Herm. MuUer, 'Fertilisation,' pp. 74-6, 'Weit. Beob.,' 

 I. P- 319 ; Verhoeff, ' Bl. u. Insekt. a. d. Ins. Norderney,' p. 127 ; Kirchner, ' Flora 

 v. Stuttgart,' p. 265; MacLeod, Bot. Jaarb. Dodonaea, Ghent, vi, 1894, p. 175; 

 Knuth, 'Bl. u. Insekt. a. d. nordfr. Ins.,' pp. 18, 147.) — The bright yellow blossoms 

 are protandrous. Immediately after the flower has opened, the anthers of the 

 outermost stamens dehisce, so that their outer sides are covered with pollen, some 

 of which must adhere to insects seeking the nectar secreted by the bases of the 

 petals. At this stage the incompletely mature stigmas are completely, or almost com- 

 pletely, covered by the inner stamens, being thus guarded from contact with insect 

 visitors. Centripetal dehiscence of the anthers slowly takes place, each stamen 

 in tirni bending outwards, so as to direct its pollen-covered side towards the petals. 

 The stigmas are mature before the anthers of the innermost stamens have dehisced. 

 Should insects covered with pollen alight on the middle of the flower, crossing must 

 result, while if they settle upon a petal, afterwards creeping over the stamens to the 

 stigmas, there is an equal chance of self-pollination, which at this stage may also 

 take place automatically. Herm. Miiller states that the two modes of alighting are 

 about equally common in this and the next three species. 



Visitors. — In consequence of its relatively small flowers, R. Flammula attracts 

 but few insects. The following have been observed by Hermann Miiller (H. M.), 

 Verhoeff (V.) in Norderney, and by myself (Kn.) in Schleswig-Holstein. — A. Coleo- 

 ptera. Staphylinidae : i. Anthobium minutum F., freq. (H. M., Teutoburger 

 Wald). B. Diptera. (a) Muscidae: 2. Anthomyia sp. (Kn., Fohr; H. M., V.); 

 3. Scatophaga merdaria L., po-dvg. (H. M.); 4. S. stercoraria F., po-dvg. (Kn., 

 Kiel), {b) Syrphidae: 5. Cheilosia sp., po-dvg. (H. M.) ; 6. Eristalis tenax Z., 

 po-dvg. (Kn., Kiel); 7. Melithreptus taeniatus Mgn., po-dvg. and skg. (H. M.) ; 



