542 



ANGIOSPERMAEDICOTYLEDONES 



localities, and only occasionally observed such relations. He found, on the contrary, 

 that the first flowers to open in each main and lateral axis are hermaphrodite, while 

 the later ones are mostly male. The hermaphrodite flowers are more or less dis- 

 tinctly protandrous, rarely homogamous. Self-pollination is therefore rare or 

 impossible, despite the centripetal movement of the stamens. 



Visitors. Schulz observed bees, and Schletterer (Pola) noticed the saw-fly 

 Athalia rosae Z., var. cordata Lep. 



In Dumfriesshire, 7 hover-flies and several Dolichopodids were recorded 

 (Scott-Elliot, 'Flora of Dumfriesshire,' p. 84). 



1244. G. Mollugo L. (Herm. Mttller, 'Fertilisation,' pp. 300-1, 'Weit. Beob.,' 

 Ill, pp. 69-70 ; Knuth ' BL u. Insekt. a. d. nordfr. Ins.,' ' Blutenbiol. Beob. a. d. 

 Ins. RUgen'; Schulz, 'Beitrage,' I, p. 67; Kerner, 'Nat. Hist PI.,' Eng. Ed. 1, 

 II, p. 344.) The small white flowers of this species are arranged in conspicuous 

 inflorescences. Hermann Mailer describes them as protandrous. Like all our native 

 Rubiaceae, they secrete nectar on a disk above the ovary, and surrounding the base 

 of the style. The quantity is very small, and forms only a thin layer. 



Fig. 181. Galium Mollugo, L. (after Herm. Mailer), (i) Young flower, with erect stamens and 

 styles. (a) Older flower with stamens carved oat of it, and styles diverging. (3) Middle of the flower, 

 seen from above, more highly magnified, a, stigma ; 6, fleshy disk of the ovary. 



In younger flowers the stamens are erect, with anthers pollen-covered all over, 

 while the two capitate stigmas are still closely apposed, but already receptive. The 

 stamens subsequently spread out, and finally bend quite out of the flower ; the two 

 styles also diverge. In this second stage, therefore, cross-pollination is likely to 

 result from the visits of insects. Schulz states that autumn plants in particular are 

 frequently homogamous, and as in these the anthers are at first situated above the 

 stigmas, self-pollination may take place. I have never observed the incurving of 

 the stamens leading to autogamy that is described by Kerner as occurring in this 

 species, G. infestum, and G. tricorne. 



Visitors. I observed the following Diptera, skg., in the island of Sylt (' Weit. 

 Beob. fi. Bl. u. Insekt. a. d. nordfr. Ins.,' p. 235). 



1. Coenosia tigrina F. ; 2. Dolichopus aeneus Deg. ; 3. Hylemyia sp. ; 4. H. 

 variata F. ; 5. Sargus cuprarius Z. ; 6. Scatophaga stercoraria Z. ; 7. Spilogaster 

 communis R.-D.\ 8. S. duplaris Zeti.\ 9. S. duplicata Mg. ; 10. Stomoxys stimulans 

 Mg. 5; 11. Thereva nobilitata F. ; and in RUgen the beede Cantharis fulva Scop., 

 po-dvg. 



Herm. Miiller gives the following list. 



A. Coleoptera. Oedemeridae : 1. Oedemera podagrariae Z., po-dvg. (Thurin- 

 gia). B. Diptera. {a) Bombyliidae: 2. Anthrax flava Mg., not infrequent, nect- 

 1kg. (Thuringia) ; 3. Systoechus sulphureus Mik., skg., probably piercing the 



