GENTIANEAE 



107 



The anthers dehisce when the flower opens, their pollen-covered surfaces being 

 directed upwards, so that if the head of a humble-bee is thrust into the corolla-tube 

 it must touch them. The two stigmas simultaneously diverge, and as they project 

 beyond the anthers cross-pollination is favoured, though autogamy is not excluded. 



In plants from the DovreQeld and Nordland, according to Lindman and 

 Warming respectively, automatic self-pollination is easily possible, for the anthers 

 generally touch the stigma. 



Wamstorf describes the pollen-grains as whitish in colour, ellipsoidal, densely 

 papillose, about 56 /x long and 44 /x broad. 



Visitors. Herm. MuUer observed a humble-bee (Bombus sylvarum Z., with 

 a proboscis of 1 2-1 4 mm.), skg. 



1916. G. germanica Willd. (Ricca, Atti Soc. ital. sc. nat., Milano, xiii, 1870; 

 Schulz, 'Beitrage'; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, pp. 302, 311.) The 

 large flowers of this species attain an average length of 28-32 mm., and are violet in 

 colour, often with a whitish tube ; rarely pure white, and still more rarely yellow. 

 They are heterostylous humble- 

 bee Lepidopterid flowers, de- 

 scribed by Schulz as feebly or 

 strongly protandrous, by Kerner 

 as protogynous. The nectaries 

 are situated as in G. Amarella. 

 Schulz states that the anthers 

 are at first directed inwards, 

 but gradually twist themselves 

 round till they face outwards. 

 In the homogamous or feebly 

 protandrous flowers automatic 

 self-pollination is possible, owing 

 to the stigma and anthers being 

 at the same level, but the out- 

 wardly directed position of the 

 latter renders it difiicult. The 

 flowers are homogamous in the 

 Alps, but the stigma is at a higher 



level than the anthers, so that autogamy is impossible. 



Kerner describes the Alpine sub-species G. rhaetica Kerner as being hetero- 

 stylous and protogynous. 



Visitors. Ricca observed the honey-bee and humble-bees ; Schulz noticed 

 flowers perforated by the latter. 



1917. G. obtusifolia Willd. (Herm. Miiller, ' Alpenblumen,' p. 348 ; Schulz, 

 ' Beitrage.') This species bears protandrous humble-bee Lepidopterid flowers, which 

 Schulz describes as gynomonoecious. As a rule the style projects beyond the anthers 

 down to the point where it bifurcates. There are, however, some flowers with 

 shorter styles, the branches of which roll back and take up the pollen still clinging to 

 the anthers, thus effecting automatic self-pollination. 



Fig. 266. Gentiana ciliala, Z. (from Herm. Miiller's 'Alpen- 

 blumen'). A. Exterior of flower, seen from the side, in first (male) 

 stage. B. Do., partly dissected. C. Pistil of same. D. Flower 

 in second (female) stage, partly dissected from the side, a, anthers; 

 fit filaments ; n, nectary ; ov, ovary ; sd, nectar-cover ; si, stigma. 



