COMPOSITAE 683 



Herm. Miiller (Alps), 3 beetles, 2 flies, 4 bees, and 14 Lepidoptera. Loew 

 (Alps), the hawk-moth Zygaena exulens Hochw. et Rein: (Altvatergebirge), 11 

 hover-flies, skg. — i. Cheilosia canicularis Pz.; 2. C. sp. ; 3. Didea intermedia 

 Lonv; 4. Platycheirus manicatus Mg.; 5. Sericomyia borealis Fall.; 6. Syrphus 

 annulipes Zell.; 7. S. cinctellus Ze/l.; 8. S. corollae F.; 9. S. lunulatus Mg.; 

 10. S. pyrastri L.; 11. S. topiarius Mg. 



497. Taraxacum L. 



Florets yellow. Style covered externally with sweeping -hairs that extend 

 considerably below the cleft, and are directed obliquely upwards ; stylar branches 

 beset with stigmatic papillae internally, and rolling up to a marked degree. 

 Kerner says that in the outer florets these branches diverge and roll back to such 

 an extent that they come into contact with the pollen of the inner ones. 



Amqng the species native to Denmark, Raunkjser (Bot. Tids., Kjobenhavn, xxv, 

 1903, pp. 109-40) found some plants in which the anthers were always devoid 

 of pollen, and which were therefore purely female (T. paludosum Scop., T. Osten- 

 feldii Raunlj., T. speciosum Raunkj., and T. decipiens Raunkj). He cut off' with 

 a razor the upper half of an unopened capitulum of such a plant, leaving only 

 the lower part of the corolla-tubes, filaments, and styles, together with the ovaries. 

 In spite of this severe treatment the last developed into perfect fruits. The same 

 experiment was tried with the same result in hermaphrodite species (T. vulgare Lam., 

 T. intermedium Raunkj., and T. Gelertii Raunkj.), including the S. European form 

 T. obovatum DC, and the Pamir species T. glaucanthum DC. As in these cases 

 no germinating pollen-grains could be found on the stigmas, Raunkjser regarded the 

 species named as parthenogenetic. 



1630. T. officinale Wigg. (=Leontodon Taraxacum £.). (Hildebrand, 'U. d. 

 Geschlechtsverhalt. b. d. Compositen,' pp. 7-13, Taf. I, Figs. 1-7; Herm. MuUer, 

 'Fertilisation,' pp. 359-61, 'Weit. Beob./ Ill, pp. 94-5, ' Alpenblumen,' p. 464; 

 Loew, ' Bliitenbiol. Floristik,' pp. 390, 394, 398 ; Lindman, ' Bidrag till Kanned. om 

 Skandin. Fjellvaxt. Blomn. o. Befrukt.'; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, 

 pp. 217-18, 319; H. de Vries, Ned. Kruidk. Arch., Nijmegen, 2. Ser., 2. Deel, 

 1875; MacLeod, Bot. Jaarb. Dodonaea, Ghent, iii, 1891, v, 1893; Knuth, 'Bl. 

 u. Insekt. a. d. nordfr. Ins.,' pp. 97-8, 162, ' Bl. u. Insekt. a. Helgoland'; Warnstorf, 

 Verh. bot. Ver., Berlin, xxxviii, 1896, xxxix, 1897, xl, 1897; Benecke, Bar. D. bot. 

 Ges., Berlin, ii, 1884, p. 192.) — In this species the yellow capitula are 30-50 mm. 

 broad when expanded in the sunshine: on the Dovrefjeld Lindman observed 

 abnormally large inflorescences of a bright yellow-red colour, with a diameter of as 

 much as 60 mm., and possessing greatly enlarged marginal florets. At night and 

 during dull weather the heads remain closed. Linnaeus says that they open at 

 5-6 a.m. at Upsala, closing again as early as 8-10 a.m. At Innsbruck, according to 

 Kerner, they open at 6-7 a.m., and close at 2-3 p.m. Benecke states that when 

 the heads open, the outer involucral bracts first fold back as a result of the more 

 vigorous growth of their inner surfaces. The inner involucral bracts are only 

 passively turned outwards by the opening of the florets, and this holds for the 

 first expansion of the head, as well as for every time it subsequently opens during the 

 morning ; in the evening these bracts close in again owing to their elasticity. 



