92 



A NGIOSPERMAEDICOTYLEDONES 



the stigma during the second stage of flowering. This self-pollination is effective, 

 according to Comes ('Stud. s. impoll. i. ale. piante'). 



Visitors. Hermann Muller (H. M.) and myself (Kn.) have observed the 

 following. 



A. Diptera. (a) Muscidae: i. Anthomyia sp., po-dvg. (H. M.). (b) Syrphidae: 

 2. Ascia podagrica F., in large numbers, po-dvg. (H. M.). B. Hymenoptera. 

 Apidae : 3. Apis mellifica Z., skg. (Kn.) ; 4. Andrena dorsata K., po-cltg. and skg. 

 (H. M.) ; 5. Halictus morio F. S, skg. (H. M.). C. Lepidoptera. 6. Pieris brassicae 

 Z., skg. (Kn.); 7. P. napi Z., skg. (H. M., Kn.); 8. P. rapae Z., skg. (H. M.). 



Alfken noticed the following Apidae at Bremen. 1. Prosopis communis Nyl. 5; 

 2. Eriades nigricornis Nyl. 5. Schletterer saw at Pola the two bees Andrena florea 

 F., freq., skg., and Halictus calceatus Scop. ; also the fossorial wasp Pemphredon 

 unicolor F., very freq. 



2 



-a 



FlG. 30. Sisymbrium. (From nature. Semi-diagrammatic, and enlarged.) Two of the long 

 stamens, two petals, and the anterior sepal have been removed, (i) S. officinale L.. Flower in the first 

 stage; the anthers of the long stamens (a) are at the same level as the stigma (.y), those of the short ones(a') 

 are lower. (2) S. officinale. Flower in the second stage : the anthers of the long stamens project beyond 

 the stigma, those of the short stamens are at the same level. (3) S. Sophia L. Flower in the second 

 stage ; k, calyx ; c, petal ; , nectary. 



MacLeod observed 2 bees, 3 hover-flies, and a Muscid in Flanders (Bot. Jaarb. 

 Dodonaea, Ghent, vi, 1894, pp. 199-200). 



In Dumfriesshire (Scott-Elliot, ' Flora of Dumfriesshire,' p. 14) a Muscid and 

 a hover-fly have been recorded. 



213. S. Sophia L. (Kirchner, 'Beitrage,' pp. 20-1; MacLeod, Bot. Jaarb. 

 Dodonaea, Ghent, vi, 1894, p. 200; Kerner, 'Nat. Hist. PI./ Eng. Ed. 1, II; Knuth, 

 'Bl. u. Insekt. a. d. nordfr. Ins.,' pp. 26-7, 'Weit. Beob. ii. Bl. u. Insekt. a. d. nordfr. 

 Ins.,' p. 231.) Although this plant attains a height of 1 m., and possesses a many- 

 flowered inflorescence, it is not very conspicuous, for the diameter of the individual 

 flowers is only 3 mm., and their colour is yellowish-green. The petals are only 

 half as long as the sepals (see Fig. 30), and scarcely differ from them in colour, 

 so that they have almost entirely lost their original function. Stigma and stamens 

 according to my own investigations mature simultaneously, and have the same 

 relative position as in the last species. The nectaries are also in the same position, 

 judging from my observations on plants in the North Frisian Islands, though 

 Velenovsk^ figures an irregular swollen nectary covering the entire base of the 

 flower. Kerner states that there is slight protogyny, but that the difference between 

 the times of maturation of stamens and stigma only amount to a few hours. 

 Automatic self-pollination is therefore inevitable. Warnstorf (Verh. bot. Ver., Berlin, 

 xxxvii, 1895) describes the pollen-grains as pale yellow, ellipsoidal, very finely 

 papillated or almost smooth, 18-19 fi broad and 25-31 /* long. 



