COMPOSITAE 



581 



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. PL,' Eng. Ed. i, II; Loew, ' Bliitenbiol. 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 

 poUen 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. MuUer (Alps), 2 beetles, 2 bees, 36 Lepidoptera, and 9 flies. Knuth 

 (Andermatt, July, 1878), 3 hover-flies (Eristalis tenax L., 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 



M 







Xl 



Fig. 105- Aster Tripolium^ L. (from nature), (i) Floret in the first (male) stape : 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 II 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- 



