348 ANGIOSPERMAE—DICOTYLEDONES 



Jaarb. Dodonaea, Ghent, vi, 1894, p. 144; Kirchner, 'Flora v. Stuttgart,' p. 216; 

 Verhoeff, ' Bl. u. Insekt. a. d. Ins. Norderney'; Knuth, 'Beitrage.') — The flower 

 mechanism agrees with that of the preceding species ; there are, however, usually 

 six to eight, more rarely five stamens, which are of about the same height as the 

 three stigmas, and mature simultaneously with the anthers. The flowers are small 

 and pink, or more rarely white, in colour. There may be pseudo-cleistogamy as in 

 P. mite. 



Visitors. — Herm. Miiller observed 4 hover-flies — i. Ascia podagrica /"., skg. ; 

 2. Melithreptus menthastri L., skg. and po-dvg. ; 3. i\I. pictus Mg., do. ; 4. Syritta 

 pipiens L., skg. 



2480. P. aviculare L. (Herm. Miiller, 'Fertilisation,' p. 515; MacLeod, Bot. 

 Jaarb. Dodonaea, Ghent, vi, 1894, p. 144; Kirchner, 'Flora v. Stuttgart,' p. 216; 

 Verhoeff, ' Bl. u. Insekt. a. d. Ins. Norderney ' ; Knuth, ' Beitrage.') — The flowers 

 of this species are very small (scarcely 2I mm. in diameter), and green in colour, 

 with purple-red or white edges. As they are devoid of nectar and odourless, and 



situated singly in the leaf-a.xils, they possess 

 very little power of attraction and very rarely 

 receive insect-visits ; they are, in fact, almost 

 limited to automatic self-pollinadon, which is 

 very effective, as almost all flowers set fruits. 

 The perianth leaves diverge widely. The 

 B,^ „, n / ■ » , , f five stamens that alternate with them bend 



rlG. .^55. Foly^onitni aviculare^ L. (after 



Herm. Muiier). (i) Flower sMn from above. outwards, whilc the three Others bend inwards, 



(2) Do., after removal of the two front perianth . . i , • i i 



leaves and half the stamens ; seen from the side. SO that they are brought JUSt abOVe the tWO 



!/,\"t^ls'""" ""'* °"'" """""' ''"''°™''^' Stigmas, which mature simultaneously with 



them. Automatic self-pollination is therefore 

 inevitable by fall of pollen. When the flowers are visited by insects either self- or 

 cross-pollination may be effected with equal facility. Although the filaments possess 

 a fleshy thickening at the base, no secreUon of nectar is to be found, the flowers 

 offering only pollen to visitors. Hermann Miiller observed, however, that Syritta 

 pipiens not only devoured pollen, but inserted its proboscis into the base of the 

 flower : it either sought nectar in vain or licked off a shallow layer. 



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

 stated. — 



Verhoeff (Norderney), the hover-fly Syrphus corollae F. Knuth (Kiel), the 

 hover-fly Syrphus balteatus Deg., po-dvg. Herm. Miiller (Westphalia), 3 hover-flies^ 

 I. Ascia podagrica F.^ po-dvg.; 2. Melithreptus menthastri Z., do. ; 3. Syritta pipiens 

 Z., and perhaps also skg. 



2481. P. Convolvulus L. (Kirchner, -Flora v. Stuttgart,' p. 212; Knuth, 

 ' Bl. u. Insekt. a. d. nordfr. Ins.,' p. 166.) — The flowers of this species belong to 

 classes C to EC. Although they are situated in fascicles in the leaf-axils, they receive 

 few insect-visits on account of their small size and the inconspicuousness of the green, 

 white-edged perianth. Kirchner says, therefore, that they are almost entirely restricted 

 to automatic self-pollination. Anthers and stigmas mature simultaneously ; but the 

 flowers at first open so widely that these organs do not come into contact. Gradually, 



