ROSACEAE 389 



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

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

 of the petals changes into pink. 



264. Amelanchier Medic. 



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

 nectar, or yielding only pollen (?). 



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

 L., 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.) — 

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

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

 not become receptive till all the anthers have dropped off. The nectar is exposed, 

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

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

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

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

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

 succession. 



Visitors. — Herm. Muller 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 Toney et Gray (=A. Botryapium DC). (Kirchner, 

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

 conspicuous 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, 

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

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

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

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

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

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

 of nectar was not observed, probably however only because the weather was dull 

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

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

 infer that nectar is actually secreted by the former. 



265. Cydonia Tourn. 



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

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



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

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

 1897, 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. 



