POLYGON ACEAE 349 



however, the stamens bend so far inwards that the anthers (three of which sometimes 

 remain closed, while the others dehisce inwards) dust the stigmas with pollen. Nectar 

 is secreted in small quantities at the base of the stamens. Kerner observed pit-like 

 nectaries on the leaf-stalks. 



Visitors. The following were recorded by the observers, and for the localities 

 Stated. 



Knuth (Kiel, on a hot afternoon after prolonged rain), 2 bees Apis mellifica 

 L. 5, freq., skg., and Halictus flavipes F. 5, occasional, skg., with an equal chance 

 of self- and cross-pollination. MacLeod (Flanders), a hover-fly (Syritta sp.), Bot. 

 Jaarb. Dodonaea, Ghent, vi, 1894, p. 146. 



2482. P. dumetorum L. (Kirchner, 'Flora v. Stuttgart,' p. 214.) The green, 

 homogamous flowers of this species are situated in fascicles in the leaf-axils, and 

 expand in the sunshine. Their mechanism agrees with that of the preceding species, 

 the eight stamens bending first outwards and then inwards, so that the eight anthers 

 can automatically pollinate the stigmas, which mature simultaneously with them and 

 stand at the same level. 



2483. P. cuspidatum Sieb. et Zucc. (Knuth, ' Bliitenbiol. Notizen.') The 

 odourless flowers of this species are aggregated into large, crowded racemes, and 

 therefore very conspicuous. 



Visitors. The following were recorded by the observers, and for the localities 

 stated. 



Knuth (Kiel Oberrealschule Garden, 11. 9. '97), large numbers of the following 

 Muscids, skg. i. Anthomyia sp. ; 2. Calliphora erythrocephala Mg. ; 3. C. vomitoria 

 Z. ; 4. Lucilia caesar Z. ; 5. L. cornicina F.; 6. Musca cervina F.\ 7, M. domestica 

 Z. ; 8. Sarcophaga carnaria Z. ; 9. Scatophaga stercoraria Z. Loew (Berlin Botanic 

 Garden), 2 Muscids Graphomyia maculata Scop., and Lucilia caesar Z. 



767. Koenigia L. 



2484. K. islandica L. The flowers of this species belong to class C. Axell 

 states that they possess three comparatively large, swollen, yellow nectaries alternating 

 with the three stamens. Self-pollination takes place as a rule in consequence of the 

 simultaneous maturation, equal length, and proximity of anthers and stigma. Anders- 

 son and Hesselman state that the species flowers on Spitzbergen from mid-July to 

 .mid-August ('Bidrag till Kanned. om Spetsbergens o. Beeren Eil. Karlvaxtflora,' 

 p. 66). 



768. Emex Neck. 



2485. E. spinosa Campd. (S. Murbeck, ' U. einige amphikarp. nordwestafrik. 

 Pfl.,' Vet.- Ak. Ofvers., Stockholm, Iviii, 1901-2; Bot. Centralbl., Cassel, xci, 1903, 

 p. 26.) Murbeck states that the South European and North African species bears 

 unisexual flowers, the female ones being partly subterranean. These are larger than 

 the aerial form, and possess a fleshy spongy perianth, and elongated stigmas which 

 project above the surface. 



