io8 ANGIOSPERMAEDICOTYLEDONES 



I 



Visitors. Herm. Muller observed 3 humble-bees (including Bombus mastru- 

 catus Gerst., and B. terrester Z., obtaining nectar by perforating the flowers), and 

 a Lepidopterid. 



1918. G. ciliata L. (Herm. Mflller, op. cit., pp. 343-4 ; Delpino, ' Ult. oss.,' 

 pp. 166-7 j Hildebrand, Bot. Ztg., Leipzig, xxviii, 1870, pp. 668-9 ') Schulz, * Beitrage '; 

 Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, pp. 163, 300, 311.) This species bears 

 protandrous humble-bee flowers which smell like violets. Schulz states that they are 

 sometimes homogamous, and Kerner describes them as trimonoecious. The anthers 

 are at first directed inwards, but dehisce extrorsely in the first stage of anthesis and 

 cover their outer sides with pollen. They are usually empty when the stigmatic lobes 

 expand, and automatic self-pollination consequently only takes place occasionally. 

 Nectar is secreted by five elongated raised patches of a shining green colour at the 

 base of the corolla, and bees or Lepidoptera probing for this must regularly eflfect 

 cross-pollination. 



Visitors. Schulz observed bees, more rarely Lepidoptera. Herm. Muller and 

 Schulz noticed flowers perforated by humble-bees. Kerner says that the flowers serve 

 as a refuge to small beetles. 



583. Erythraea Rich. 



I 



Flowers usually rose-red, rarely white in colour; homogamous, more rarely, 

 feebly protandrous or protogynous ; nectarless, but possessing succulent basal tissue 

 which insect visitors bore *. Heterostyly frequent. 



1919. E. Centaurium Pers. (=Gentiana Centaurium Z.). (Sprengel, 'Entd. 

 Geh.,' p. 152; Herm. Muller, 'Fertilisation,' p. 407, 'Weit. Beob.,' Ill, p. 61; 

 Kirchner, ' Flora v. Stuttgart,' p. 543, ' Neue Beob.,' p. 63 ; Schulz, ' Beitrage,' 

 I, p. 71 ; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 213; MacLeod, Bot. Jaarb. 

 Dodonaea, Ghent, v, 1893, PP- 382-3; A. Stephen Wilson, Rep. Brit. Ass., London, 1 

 1878, p. 568; Warnstorf, Verb. bot. Ver., Berlin, xxxviii, 1896; Knuth, *B1. u. 

 Insekt. a. d. nordfr. Ins.,' pp. 105-6, 164.) The plants of this species examined 

 by me in the North Frisian Islands were homogamous. The stigmas are mature 

 when the flower opens, at which time the anthers dehisce successively, but 

 autogamy is at first prevented by bending of the style to one side, and the 

 stamens, as their anthers dehisce, to the opposite side. Later on the stamens 

 raise themselves to a height of 4 mm., and the somewhat shorter style also 

 becomes erect, so that the anthers with some pollen still adherent are brought 

 above the stigma, and automatic self-pollination results from the fall of pollen. 

 Autogamy may also in many cases take place immediately after the flowers 

 have opened, for not infrequently there is no lateral bending of style and stamens. 

 During bad weather, and when the flowers begin to fade, this kind of pollination 

 is inevitably brought about by convergence of the corolla-lobes. Wilson observed 



' When flowers of Erythraea Centaurium were treated (i 7. 8. '98) with Fehling's solution 

 and orthonitrophenylpropionic acid, only the former caused a small amount of copper oxide to 

 be precipitated in the base of the flower, while the latter gave no indigo reaction. Only a small 

 amount of sap can therefore be present. 



