COMPOSITAE 



5Si 



self-pollination occurs in the latter, by crossing of the stylar branches, but I have 

 never noticed this. 



1325. A. alpinus L. (Herm. Miiller, ' Alpenblumen,' pp. 447-8; Kerner, 'Nat. 

 Hist. PI./ Eng. Ed. 1, II; Loew, 'Blutenbiol. Floristik/ p. 397 ; Knuth, 'Bloemen- 

 biol. Bijdragen.') This species is gynomonoecious, with protandrous [hermaphrodite 

 florets. The 50-150 yellow disk-florets are surrounded by 24-40 violet ray-florets, 

 making up a terminal head 32-45 mm. in diameter. The style with its two diverging 

 branches projects 2-3 mm. out of the ray-florets. From the bells of the disk-florets 

 pollen is first extruded, and then the stylar branches, which curve together above, 

 make their appearance. Kerner states that the stigmas of the female florets became 

 receptive several -days before pollen is produced by the neighbouring hermaphrodite 

 florets. 



Visitors. The following were recorded by the observers, and for the localities 

 stated. 



Herm. Miiller (Alps), 2 beetles, 2 bees, 36 Lepidoptera, and 9 flies. Knuth 

 (Andermatt, July, 1878), 3 hover-flies (Eristalis tenax Z., Helophilus trivittatus F., 

 Melanostoma mellina Z., skg. and po-dvg.), and numerous Lepidoptera. Loew 

 (Switzerland), a hover-fly (Cheilosia caerulescens Mg.), and a butterfly (Lycaena sp.). 



1326. A. Tripolium L. (Knuth, ' Bl. u. Insekt. a. d. nordfr. Ins.,' pp. 86-7, 

 157, 'Weit. Beob. ii. Bl. u. Insekt. a. d. nordfr. Ins.,' p. 235; MacLeod, Bot. 

 Centralbl., Cassel, xxix, 1887.) The heads of this species are about 20 mm. in 

 diameter, each containing 20-30 bright violet female ray-florets, with a corolla-lobe 



Fig. 195. Aster Tripolium, L. tfrom nature), (i) Floret in the first (male) stage : the pollen is 

 being extruded from the tip of the anther-cylinder; the lobes of the corolla are spread out. (2) Ditto, in 

 the second (female) stage ; the projecting style is provided with apical sweeping-hairs, and below these are 

 stigmatic papillae ; the anther-cylinder has retracted into the corolla, the lobes of which now point 

 upwards. (3) Greatly enlarged tip of the style of a floret in the female stage ; above are the sweeping- 

 hairs, and below the stigmatic papillae. (4) A stylar branch seen from the outside ; above and in the 

 middle are sweeping-hairs ; below and laterally stigmatic papillae. (5) Ditto, from within. 



about 11 mm. long and 2\ mm. broad, and an equal number of yellow tubular 

 hermaphrodite disk-florets. Owing to the colour contrast presented by the ray- 

 and disk-florets, as well as the crowding together of numerous heads, the plant 

 is rendered very conspicuous. The corolla of the disk-florets is contracted below 

 like a stalk for a length of 4 mm., expanding above into a bell 2 mm. long. The 

 pollen is swept out by the rhombic tips of the stylar branches, which are provided 

 with sweeping-hairs directed obliquely upwards. When the anther-cylinder is empty, 

 the stylar branches project 2 mm. from the inflorescence. Below the collecting- 



