674 



ANGIOSPERMAEDICOTYLEDONES 



489. Leontodon L. 



Florets yellow. Styles rather closely covered outside with sharp sweeping-hairs 

 extending far above the cleft ; inner surfaces of the stylar branches which sometimes 

 do not entirely separate densely beset with stigmatic papillae. Kerner states that 

 geitonogamy by pollen from the inner florets is automatically effected by the spreading 

 of the stylar branches. He further remarks that automatic self-pollination may also 



be brought about by gradual elonga- 

 tion of the ligulate corolla, which 

 thus carries up the pollen adhering 

 to it. 



1 6 11. L. autumnalis L. (Herm. 

 Miiller, ' Fertilisation,' pp. 356-8, 

 Weit. Beob.,' Ill, pp. 96-7 ; Knuth, 

 'Bl. u. Insekt. a. d. nordfr. Ins./ 

 pp. 96-7, 161, 'Bl. u. Insekt. a. d. 

 Halligen,' p. 37, 'Weit. Beob. ii. BL 

 u. Insekt. a. d. nordfr. Ins.,' pp. 236-7, 

 'Blutenbiol. Beob. a. d. Ins. Rvigen,' 

 ' Bloemenbiol. Bijdragen'; Lindman, 

 ' Bidrag till Kanned. om Skandin. 

 Fjellvaxt Blomn. o. Befrukt.'; Verhoeff, 

 1 Bl. u. Insekt. a. d. Ins. Norderney ' ; 

 MacLeod, Bot. Jaarb. Dodonaea, 

 Ghent, v, 1893.) The heads of this 

 species expand in the sunshine to 

 form a golden-yellow disk 20-30 mm. 

 broad, but in rainy weather they 

 contract to a diameter of 5 mm. 

 Hermann Miiller says that each head 

 contains 40-70 florets, with corolla- 

 tubes 2^-5 mm. and ligules 7-1 2 mm. 

 long. The style projects 3-4 mm. 

 beyond the tube, into the wider part 

 of which the nectar rises. If insect- 

 visitors are sufficiently numerous at 

 the right time, the pollen is removed 

 from the sweeping-hairs before the 

 stigmatic surfaces unfold; at a later 

 stage insects may effect self-pollination. 

 The latter may also take place automatically should insect-visits fail, by the stigmatic 

 surfaces coming into contact with the pollen. 



Visitors. Knuth observed the following in Schleswig-Holstein (S.-H.), Riigen 

 (R.), and the dunes and high land of Helgoland (H). 



A. Coleoptera. (a) Chrysomelidac: 1. Cryptocephalus sericeusZ., po-dvg.(R). 

 (6) Telephoridae : 2. Psilothrix cyanea 01., po-dvg.(H). B. Diptera. (a) Muscidae 



FlG. 209. Leontodon autumnalis, L. (after Herm. Miiller). 

 (1) Floret in the second (female) stage, after removal of 

 calyx and ovary (X 7). (a) End of style of do. (x 35). 

 a, sweeping-hairs ; 6, stigmatic papillae ; c, pollen-grains. 





