GENTIANEAE . 99 



Visitors. Heinsius observed the following. 



The bee Apis mellifica Z. ^, touching the anthers of the short stamens and the 

 stigma of the short style with its thorax, and the corresponding parts of the long- 

 styled form with its abdomen, 2 humble-bees (apparently Bombus agrorum I^., and 

 B. scrimshiranus X.), 2 hover-flies (Platycheirus peltatus Mg. J, and Helophilus 

 lunulatus Mg. $), and 2 Muscids (Anthomyia pratensis Mg. S, and A. sp. 5). 



1890. L. Humboldtianum. (Fritz MuUer, Bot. Ztg., Leipzig, xxvi, 1868, 

 p. 13.) Fritz Miiller describes this species as dimorphous, like L. nymphoides. 



580. Chlora L. 



Flowers devoid of nectar; arranged in sub-corymbose cymes. 



1891. C. perfoliata L. (=G. perfoliata Z.). (Vaucher, 'Hist, physiol. des pi. 

 d'Europe,' III, p. 404.) Vaucher says that the yellow flowers of this species close at 

 night. The corolla-tube is closely approximated to the ovary. The two bilobed, 

 thickened, papillose stigmas are self-pollinated. 



581, Swertia L. 



Flowers more or less protandrous; with nectar secreted by minute cups sur- 

 rounded by interwoven fringes, and situated in pairs at the bases of the petals, one 

 pair to each. 



1892. S. perennis L. (Schulz, ' Beitrage ' ; Kerner, ' Nat. Hist. PI.,' Eng. Ed. i, 

 II, pp. 241, 341; Francke, 'Beitrage.') In the flowers of this species the corolla 

 varies from steel-blue through grey-white to bright yellow in colour, and the petals 

 are marked by numerous streaks. Schulz says that now and then the pistil or some 

 of the stamens may be reduced, but complete gynodioecism or androdioecism is rare. 

 The anthers of hermaphrodite flowers dehisce a longer or shorter time after the 

 maturation of the stigma. Francke and Schulz state that the stamens are bent back 

 so much that self-pollination is excluded. Kerner, however, observed that autogamy 

 finally takes place, for before all the pollen is shed the stamens first straighten and 

 then move towards and pollinate the stigma. But, on the other hand, Francke and 

 Schulz assert that such autogamy is exceptional, for as a rule no pollen remains on 

 the anthers by the time they reach the stigma. 



Visitors. Schulz observed small flies and beetles in the Riesengebirge. 



1893. S. punctata Baumg. This species is native to Hungary and the 

 Siebengebirge, and Kerner states that its flower mechanism is the same as that 

 of S. perennis. 



582. Gentiana Toum. 



Flowers blue, rarely red or yellow in colour; nectar as a rule so deeply 

 concealed that only humble-bees or Lepidoptera can get at it, but exposed in 

 rare cases {c/l pp. 96-7). Hermann Miiller divides the species into five groups, 

 according to the position and mode of secretion of the nectar (' Alpenblumen/ 

 pp. 329-49). 



I. Species with exposed, freely accessible nectar : Gentiana lutea Z. 



