CRUCIFERAE 127 



Schletterer saw the small green bee Halictus mono F. at Pola. 



In Dumfriesshire, Apis, a humble-bee, Muscids, and Meligethes have been 

 recorded (Scott-Elliot, 'Flora of Dumfriesshire,' p. 19). 



315. R. sativus L. 1 Kirchner (' Flora v. Stuttgart,' pp. 302-3) has described 

 the structure of the flowers from garden specimens. The petals are white or lilac 

 with darker veins. The diameter of the expanded flower is about 20 mm. There is 

 a large cushion-shaped nectary internal to the base of each short stamen, and a 

 slender peg-like one outside the base of each pair of long stamens. The two outer 

 sepals possess dilatations at their bases for reception of the nectar. The stamens do 

 not undergo rotation, but bend horizontally outwards away from the stigma. The 

 anthers of the four long ones are at the same level as the stigma ; those of the 

 two short ones which curve more markedly outwards are 2-3 mm. below it. 

 When the flower fades the anthers of the long stamens come into contact with 

 the stigma so that, failing insect-visits automatic self-pollination is effected, which 

 results in normal fruits being set, though only about half of the ovules become seeds. 

 Insect visitors chiefly bring about cross-pollination. 



Visitors. Kirchner observed bees (Apis, species of Bombus), hover-flies, butter- 

 flies (Pieris), and beetles (Meligethes). Schletterer gives the following Apidae for 

 Pola in the Tyrol. 



1. Andrena carbonaria Z. ; 2. A. deceptoria Schmiedekn. ; 3. A. flavipes Pz. ; 



4. A. gwynana jX*. ; 5. A. nana -S". ; 6. A. thoracica F. ; 7. Eucera clypeata Zr. ; 



8. E. longicornis Z. ; 9. Halictus calceatus Scop. ; 10. H. malachurus K. ; 11. Poda- 



I lirius acervorum Z. ; 12. P. nigrocinctus Lep. ; 13. P. retusus Z., var. meridionalis 



Pfr.; 14. Xylocopa violacea Z. 



Andrena gwynana K. was also observed in the Tyrol by von Dalla Torre. 

 MacLeod noticed 3 flies and 2 Lepidoptera in Flanders (Bot. Jaarb. Dodonaea, Ghent, 

 vi, 1894, p. 209). 



101. Lobularia Desd. 



316. L. maritima Desd. Hildebrand states that this species is self-sterile 

 (Ber. D. bot. Ges., Berlin, xiv, 1896). 



317. L. nummularia Stend. According to Kerner ('Nat. Hist. PI.,' Eng. 

 Ed. 1, II, p. 339), this species is protogynous, but towards the end of anthesis 

 autogamy is brought about by the stamens moving towards the middle of the flower, 

 so that the pollen of the long ones reaches the stigma. 



102. Clypeola L. 



318. Clypeola Messanensis. As No. 3 1 7 (cf. loc. cit.). 



103. Sobolewskia Bieb. 



319. S. clavata Frenzl. Hildebrand (Ber. D. bot. Ges., Berlin, xiv, 1896) says 

 that this species is self-fertile. 



1 R. sativus and R. Raphanistrum are one species, according to Carriere (Andre, Belg. Hortic, 

 Liege, xix, 1869, p. 151), and Hoffmann (Bot. Ztg., Leipzig, xxx, 1872; xxxi, 1873; and xlii, 



