78 ANGIOSPERMAEDICOTYLEDONES 



flower which was intermediate between those of the two parents but rather in 

 the general form of the raceme, and in the proportion of double flowers to single. 

 Similar experiments have also been made by Schmid, Richter, and Hiltner. In- 

 formation as to these is published in ' Landwirtschaftliche Versuchs-Stationen,' Berlin, 

 xxxv, Heit 3, 1888. 



Visitors. I have observed on the species a butterfly (Pieris) ; and Schletterer 

 at Pola noticed Xylocopa violacea L. 



170. M. valesiaca Boiss. According to Briquet ('Etudes d. biol. flor. dans 

 les Alpes Occident.,' Bui. Univ. Lab. Bot., Geneve, i, 1896, pp. 16-78) the throat 

 of the corolla is whitish, while the limbs of the petals are of a dirty violet colour, 

 and spread out to form a surface 30-35 mm. across. At the base of each short 

 stamen there are two secreting nectaries, i. e. four in all. The nectar is concealed 

 in a narrow tube 8-10 mm. deep formed by the sepals and the claws of the 

 petals, and is sucked by butterflies and also by humble-bees. As the anthers of 

 the four long stamens project above the stigma, these insects chiefly effect self- 

 pollination, more rarely cross-pollination. 



171. M. nudicaulis (L.) Trautv. Ekstam says that the diameter of these 

 strongly odorous homogamous flowers is 10-20 mm. in Nova Zemlia, or sometimes 

 as much as 35 mm. The nectaries are at the bases of the short stamens. 



This species has only once been found (1827) in Spitzbergen according to 

 Andersson and Hesselman ('Bidrag till Kanned. om Spetsbergens o. Beeren Eil. 

 Karlvaxtflora,' p. 32) so that no new facts are as yet forthcoming as to its time 

 of flowering there. 



Visitors. Humble-bees have been observed. 



50. Cheiranthus L. 



Flowers of considerable size, odorous, homogamous, with nectar almost con- 

 cealed. The nectaries are two swollen ridges at the bases of the two short stamens. 

 The stigma possesses two small recurved plates. 



172. C. Cheiri L. (Herm. Muller, 'Weit. Beob.,' i, p. 324; Kirchner, 'Flora 

 v. Stuttgart,' p. 285; Knuth, 'Weit. Beob. ii. Bl. u. Insekt. a. d. nordfr. Ins.') The 

 wild plants investigated by Kirchner had bright yellow flowers. From the two 

 nectaries there project outwards to right and left two pointed processes, the nectar 

 secreted by which is stored up in dilatations of the sepals. The anthers dehisce 

 introrsely, and are so situated that they completely close the entrance to the flower. 

 The four upper ones touch the stigma with their lower ends, while the two lower 

 ones do so with their tips. It follows that automatic self-pollination is inevitable. 

 Insect-visitors, however, are more likely to effect cross-pollination, for they touch 

 the stigma and anthers with opposite sides of their proboscis. The flowers of 

 cultivated plants are usually orange- to brownish-yellow. 



Visitors. Besides the honey-bee, I have observed a hover-fly (Rhingia) 

 visiting the flowers; Hermann Muller also noted Anthophora pilipes F. $, skg. 

 nectar; and Schenck in Nassau saw Andrena flessae Pz. Burkill ('Fertlsn. of 

 spring fls.') observed on the Yorkshire coast a humble-bee, Bombus terrester L., skg. 



