POL YGONA CEAE 347 



A. Diptera. Syrphidae: i. Ascia podagrica F., very common; 2. Eristalis 

 arbustorum Z., skg. and po-dvg. ; 3. E. sepulcralis Z., comparatively freq. ; 4. E. tenax 

 Z., freq. ; 5. Melithreptus scriptus Z., skg. and po-dvg.; 6. M. taeniatus i'l^., do. ; 



7. Syritta pipiens Z., the commonest visitors. B. Hymenoptera. Apidae : 



8. Andrena dorsata A". 5, occasional, skg.; 9. Halictus albipes F. 5, do.; 10. Prosopis 

 armillata iVy/. J, do. C. Lepidoptera. Rhopalocera : 11, Pieris rapae Z., casual, 

 skg. 



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



Knuth (Holstein and Riigen), the honey-bee and the hover-fly Syritta pipiens Z. 

 Verhoeflf (Norderney), the moth Plusia gamma Z. Alfken (Juist), the humble-bee 

 Bombus hortorum Z. 5, and the butterfly Pieris brassicae Z. MacLeod (Flanders), 

 the honey-bee and 2 hover-flies (Bot. Jaarb. Dodonaea, Ghent, vi, 1894, p. 145). 

 Scott-Elliot (Dumfriesshire), 2 Muscids ('Flora of Dumfriesshire.' p. 149). 



2476. P. lapathifolium L. (Herm. Mtiller, 'Fertilisation,' p. 314; Schulz, 

 'Beitrage,' II, p. 199 ; MacLeod, Bot. Jaarb. Dodonaea, Ghent, vi, 1894, p. 145.) 

 The homogamous flowers of this species belong to classes C to EC. Their mechanism 

 agrees entirely with that of P. Persicaria. Five stamens are generally present, one or 

 more of them not infrequently coming into contact with the stigmas as they bend 

 inwards. 



Visitors. Herm. Miiller observed 3 hover-flies, skg. i. Ascia podagrica F.\ 

 2. Eristalis sepulcralis Z. ; 3. Syritta pipiens Z. 



2477. P. Hydropiper L. (Kirchner, 'Flora v. Stuttgart,' p. 218; Kerner, 

 Nat. Hist. PI.,' Eng. Ed. i, II, p. 391 ; Schulz, 'Beitrage,' II, p. 199.) The small, 

 inconspicuous flowers of this species are green outside with pink tips ; Kirchner says 

 that they are devoid of nectar, the nectaries being completely reduced. Two of the 

 eight stamens are generally vestigial ; the anthers of the other six are of the same 

 height as the stigma, so that when both organs mature simultaneously, automatic 

 self-pollination is regularly effected. Kerner states that in some flowers the perianth 

 remains closed under certain circumstances, and pseudo-cleistogamous fertilization 

 takes place. 



Schulz observed occasional gynomonoecious flowers. 



2478. P. mite Schrank (= P. laxiflorum Weihe). (Kirchner, ' Flora v. Stuttgart,' 

 p. 218 ; Kerner, ' Nat. Hist. PL,' Eng. Ed. i, 

 II, 391.) The homogamous flowers of this 

 species are a little more conspicuous than 

 those of the preceding one, for they are 

 somewhat larger and only green at the base, 

 the upper part being pink-red or white in 

 colour. Kirchner states that there is a nectary ^ ^ , z^ ^ , ,. 



' Fig. 354. Polygonum minus, Huds. (after 



at the base of each of the five to eight stamens. Herm. Mailer). (O Flower seen obliquely 



rru^ a IV .^1 J ^1 4.1 from above. (2) Do., after removal of the two 



1 he flowers open very little, and the anthers front perianth leaves ; seen from the side, a and 



are situated slightly above the stigmas (which ''': ""*" ^"'^ ""''' stamens; , nectaries; */, 

 mature at the same time), so that automatic 



self-pollination is inevitable. Kerner says that pseudo-cleistogamous fertilization 

 sometimes takes place in this species. 



2479. P. minus L. (Herm. MuUer, 'Fertilisation,' p. 514; MacLeod, Bot. 



