468 ANGIOSPERMAEMONOCOTYLEDONES 



Humble-bee visitors touch the stigma with one side of their bodies and some of 

 the pollen-covered anthers with the other, thus regularly effecting cross-pollination. 

 At the same time, however, they press the opposite side of the stigma against the 

 anthers, and thus bring about self-pollination also. This takes place automatically 

 when suitable visitors fail. 



In this species Almqvist could find no free nectar, but only sugar-containing tissue. 



Wamstorf could find no nectar in the flowers. He says that the stigmatic 

 papillae are receptive while the flowers are still closed. The style varies in length ; 

 it may be short, or reach to about the middle of the perianth tube, or even attain the 

 same level as the anthers. Stocks bearing hermaphrodite and male flowers are not 

 rare. The pollen-grains are white in colour, ellipsoidal, smooth, on an average 

 65-70 fi long and 31 /x, broad. 



Geisenheyner (Ber. D. bot. Ges., Berlin, xiii, 1895) observed a tendency to the 

 formation of male flowers at Kreuznach and other places. 



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

 stated. 



Herm. Miiller (Lippstadt), the hover-fly Rhingia rostrata Z., very freq., 

 po-dvg., and 3 bees i. Andrena fasciata Wesm. 5, skg. and po-cltg. ; 2. Bombus 

 agrorum F. 5, skg. ; 3. B. hortorum Z., do. MacLeod (Flanders), a humble-bee. 



903. Maianthemum Wigg. 



Protogynous flowers with little or no secretion of nectar at the base * of thai 

 flower. Ovary with septal glands (Grassmann). 



2809. M. convallaria Wigg. (= M. bifolium Schmidt, and Convallaria 

 bifolia Z.). (Kirchner, ' Flora v. Stuttgart,' p. 69 ; MacLeod, Bot. Jaarb. Dodonaea, 

 Ghent, v, 1893, pp. 313-14; Schulz,'Beitrage,'II, p. 168.) In the small, white, fragrant 

 flowers of this species the perianth lobes and stamens at first diverge widely ; the 

 anthers are still closed, but the stigma already receptive. The perianth lobes then 

 bend backwards again and the anthers of the stamens directed obliquely upwards 

 dehisce introrsely. When insects visit the flowers, cross-pollination is favoured by 

 the distance between stigma and anthers. Should insect-visits fail, pollen can easily 

 fall upon the still receptive stigma, in consequence of the almost vertical position of 

 the flower. Automatic self-pollination is thus easily possible. Wamstorf describes 

 the pollen-grains as white in colour, ellipsoidal, almost smooth, up to 50 fi long and 

 19/1 broad. 



Visitors. Schulz observed small flies. 



904. Streptopus Michx. 



Homogamous or feebly protogynous bee flowers, secreting nectar at the base 

 of the perianth leaves. 



2810. S. distortus Michx. (= S. amplexifolius DC, and Uvularia amplexi- 

 folia Z.). (Warming, Bot. Tids., Kjobenhavn, xvi, 1886, pp. 39-40; Schulz, 

 ' Beitrage,' I, pp. 98-9, II, p. 224.) In this species the whitish, pendulous flowers 

 are sprinkled or blotched with red on the inside and on the edges of the sepals which 



' Cf. the foot-note on Lencojam aestivum L. 



