588 ANGIOSPERMAE—DICOTYLEDONES 



5. Onesia sepulcralis Mg.; 6. Pyrellia cadaverina Z. (6) Syrphidae: 7. Eristalis 

 nemorum L. ; 8. E. sepulcralis L. ; 9. E. tenax Z. ; 10. Melanostoma mellina Z. ; 

 II. Melithreptus scriptus Z. ; 12. Syrphus balteatus Beg.; 13. S. pyrastri Z. ; 

 14. S. ribesii Z. 



422. Bellidiastrum Cass. 



Ray-florets white, female; disk-florets yellow, hermaphrodite. The stylar 

 branches of the disk-florets usually apposed above, covered with sweeping-hairs above, 

 both externally and internally, and beset with stigmatic papillae on their outer 

 margins below. Stylar branches of the female ray-florets devoid of sweeping- 

 hairs, divergent, beset with marginal and apical stigmatic papillae. 



1355- B. michelii Cass. (=Doronicum Bellidiastrum Z., Arnica Bellidiastra 

 AIL, and Aster Bellidiastrus Scop.). (Herm. Muller, ' Alpenblumen,' pp. 449-50.) — 

 This species is gynomonoecious, with protandrous hermaphrodite florets. A head 

 usually contains considerably more than 100 yellow disk-florets and 40-50 white 

 ray-florets, making up a surface 30 or more mm. in breadth. The development 

 of the florets progresses slowly in centrifugal order, so that there is never more 

 than a narrow ring of disk-florets in bloom. Kemer states that the stigmas of 

 the female florets become receptive several days before the pollen is ripe in the 

 neighbouring hermaphrodite ones (Kemer, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 312). 



Visitors. — Herm. Muller observed 5 beetles, 20 flies, 2 bees, and 14 Lepidoptera. 



423. Bellis L. 



Ray-florets white, uniserial, female; disk-florets yellow, bell-shaped, hermaphro- 

 dite. Stylar branches of the latter short, broadly ovoid, covered externally as far as 

 their broadest part wiih sweeping-hairs, beneath which on the outer margin on either 

 side is a short line of stigmatic papillae. Stylar branches of the female ray-florets 

 elongated and devoid of sweeping-hairs: stigmatic papillae more numerous than 

 in the hermaphrodite florets. 



1356. B. perennis L. (Sprengel, 'Entd. Geh.,' p. 377; Hildebrand, ' tj. d. 

 Geschlechtsverhalt. b. d. Compositen,' pp. 23-4, Taf. II, Figs. 11-15; Herm. 

 Muller, ' Fertihsation,' pp. 321-2, ' Weit. Beob.,' Ill, p. 92; Knuth, 'Bl. u. Insekt. 

 a. d. nordfr. Ins.,' pp. 87, 157; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II.) — This 

 species is gynomonoecious. Hermann Muller states that the golden-yellow 

 hermaphrodite disk-florets are only 1-2 mm. long; the white female ray-florets, 

 often tinged with red, possess tongues about 5 mm. in length. The diameter 

 of the heads averages about 16 mm., but some are considerably larger or smaller. 

 On the North Frisian Islands I observed a breadth of 10 mm. and even less. 

 The sweeping-hairs on the elongating styles of the disk-florets partly drive the 

 pollen before them, partly hold it fast, and thus present it to insect visitors. 

 Warnstorf (Verb. bot. Ver., Berlin, xxxviii, 1896) says that the stigmas of the 

 female ray-florets become receptive before the pollen of the disk-florets is ripe. 

 The latter develop centripetally. The pollen-grains are pale yellow in colour, 

 rounded, spinose, 21-5 yu, in diameter. After fertilization has been effected, the stylar 

 branches retract into the bell. Durina; dull weather and at nisrht the heads close. 



