114 ANGIOSPERMAE—DICOTYLEDONES 



In dull weather the flowers are closed or only slightly open, while even in sunshine 

 they expand so little that their opening is only about i mm. in diameter. 



279. T. montanum L. (Kirchner, ' Beitrage,' pp. 26-7 ; the description refers 

 to plants from the Swabian Alps.) — The white flowers are of considerable size, with 

 confluent nectaries. The anthers of the four long stamens are at the same level as 

 the stigma — which matures simultaneously — and turn their pollen-covered surfaces 

 towards it. The anthers of the short stamens, which are at a somewhat lower level, 

 dothis also. 



280. T. alpinum Crantz. (Kirchner, ' Beitrage,' p. 2 7 ; the description refers to 

 specimens from the RifFelberg, near Zermatt.) — The nectaries are confluent, as in the 

 last species, forming a studlike projection at the base of the flower, into which the 

 stamens are inserted. The flowers are white, and when fully expanded their diameter 

 is 7 mm. Although they are homogamous, automatic self-pollination is prevented by 

 projection of the stigma about i mm. beyond the anthers of the long stamens. All 

 six anthers turn their pollen-covered surfaces inwards : those of the long stamens 

 project a little from the entrance of the flower, while those of the short ones are about 

 I mm. within it. 



Visitors. — Pollination can only be effected by insects, but regarding these we 

 have as yet no knowledge. 



281. T. alliaceum L. — Kemer ('Nat. Hist. PI.,' Eng. Ed. i, II, p. 333) says 

 that the flowers are protogynous, but that at a later stage automatic self-pollination 

 takes place by contact of the dehiscing anthers with the stigma. 



282. T. alpestre L. — The homogamous flowers are white in colour, and their 

 anthers are first yellow, then purple-red, and finally black. 



Visitors. — Hermann Miiller observed 9 flies and 2 Lepidoptera (' Alpenblumen,' 

 p. 147). Buddeberg saw 17 bees, 7 flies, 2 saw-flies, a solitary wasp, and a beetle 

 (Justs bet. Jahresber., Leipzig, xvi (1888), 1890, p. 564). 



283. T. rotundifolium Gaud. (Schulz, ' Beitrage.') — The bright violet flowers 

 are conspicuous among the white dolomitic gravel, on which the plant grows in the 

 south Tyrol, often in patches a square metre in size. Nectar is secreted abundantly 

 at the bases of the short stamens, and concealed at a depth of 3-4 mm. The anthers 

 of the long stamens are usually at the same level as the stigma, and ultimately turn 

 completely round towards those of the short stamens. They do not touch the 

 stigma — which matures simultaneously — nor can the anthers of the short stamens 

 do so, for they are at a lower level. Automatic self-pollination does not therefore 

 take place. 



Visitors. — Schulz obsei-ved butterflies — Pieris, Vanessa cardui — and flies. 



284. T. corymbosum Gay. (Kirchner,' Beitrage,' pp. 27-8.) — On the Riffelberg, 

 near Zermatt, the flowers are bright lilac to violet in colour, fragrant, and aggregated 

 into relatively large inflorescences. The diameter of the individual flowers varies 

 from 6 to 10 mm. There is slight protogyny ; at the beginning of anthesis the 

 anthers are unripe, while the stigma — which is situated in the entrance of the flower — 

 is already mature. By the time the flowers are fully expanded the anthers of the 

 four long stamens have opened, and those of the two short ones do so soon afterwards. 



