ROSACEAE 389 



927. C. nigra Wahlenb. (= Crataegus nigra Waldsi. et Kit., and Mespilus nigra 

 Willd). Focke says that when anthesis is over in this species the white colour 

 >f the petals changes into pink. 



264. Amelanchier Medic. 



Flowers white ; homogamous, protogynous, or protandrous ; either with exposed 

 lectar, or yielding only pollen (?). 



928. A. vulgaris Moench (=A. rotundifolia C, Koch, Mespilus Amelanchier 

 C, and Aronia rotundifolia Pers.). (Herm. Miiller, ' Alpenblumen,' pp. 213-14; 

 Schulz, ' Beitrage,' II, pp. 70, 72 ; Ricca, Atti Soc. ital. sc. nat., Milano, xiv, 1871.) 

 3oth in the Alps, and according to Schulz in Central Germany, the flowers of this 

 pedes are protandrous, sometimes to so marked an extent that the stigmas do 

 lot become receptive till all the anthers have dropped off. The nectar is exposed, 

 tnd therefore accessible even to short-tongued insects. Visitors effect crossing in 

 lowers which exhibit well-marked protandry, but where this is less marked, self- 

 )ollination may also take place, and this may be automatically effected by the fall 

 )f pollen on the stigmas, should insect-visits fail. Ricca describes the flowers as 

 Drotogynous and devoid of nectar, and says that the four stamens develop in 

 succession. 



Visitors. Herm. Miiller saw 7 beetles, a Hymenopterid, 2 Muscids, and 4 

 syrphids in the Alps. Schulz observed flies, Hymenoptera, and beetles in Central 

 Germany. 



929. A. canadensis Torrey et Gray (=A. Botryapium DC). (Kirchner, 

 Beitrage,' pp. 38-9.) The flowers of this species are white, and aggregated into 

 :onspicuous racemose inflorescences : their odour resembles that of Prunus Padus. 

 Kirchner, for cultivated shrubs, describes the mechanism of the flowers as follows. 

 They are slightly protogynous, as when they open the five stigmas are mature, 

 ind occupy the middle of the flower, projecting 1-2 mm. beyond the still unripe 

 inthers. Before complete expansion, however, the outermost anthers dehisce, and 

 heir filaments become erect, attaining the level of the stigmas, but at the same 

 ime diverging so as to be several millimetres from them. The inner stamens 

 subsequently behave in the same way. Automatic self-pollination can easily take 

 Dlace in the obliquely placed flowers by fall of pollen on the stigmas. Secretion 

 :>f nectar was not observed, probably however only because the weather was dull 

 luring the days when the observations were made. The fact that the inner side 

 }f the receptacle and the bases of the styles are coated with hairs allows us to 

 nfer that nectar is actually secreted by the former. 



265. Cydonia Tourn. 



Flowers reddish-white, and of considerable size ; protogynous or homogamous ; 

 -vith half-concealed nectar, secreted by a fleshy ring at the base of the style. 



930. C. japonica Pers. ( = Chaenomeles japonica Lindl). (Herm. Miiller, 

 Weit. Beob.,' II, p. 288 ; Stadler, 'Beitrage'; Focke, Abh. natw. Ver., Bremen, xiv, 



l8 97, p. 303.) Hermann Miiller says that the flowers of this species are homo- 

 gamous ; Stadler describes them as protogynous, with a style that varies in length. 



