SCROPHULA RINEAE 



221 



672. Bartsia L. 



Homogamous or protogynous humble-bee flowers ; with nectar secreted by 

 a cushion-like swelling applied to the lower side of the base of the ovary, and stored 

 up at the bottom of the flower. Long- and short-styled forms occur sporadically. 

 Auemophily is not excluded at a later stage of anthesis. 



2171. B. alpina L. (Ricca, Atti Soc. ital. sc. nat., Milano, xiv, 1871 ; Herm. 

 Miiller, ' Alpenblumen/ pp. 283-4; Warming, ' Bestovningsmaade,' pp. 7-10, Bot. 

 Tids., Kjobenhavn, xviii, 1890, p. 226; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, 

 p. 331 ; Schulz, 'Beitrage,' II, pp. 1 18-19.) Ricca and Hermann Miiller state that 

 the flowers of this species are protogynous in the Alps. Their mechanism resembles 

 that of Melampyrum pratense as regards the structure of the corolla, and that of 

 Rhinanthus major as re- 



gards the relative posi- 

 tion of stigma and 

 anthers. Self-pollination 

 is therefore impossible 

 in Alpine flowers. 



The plants observed 

 by Schulz in the Riesen- 

 gebirge were almost 

 always homogamous or 

 feebly protogamous. 

 When the flower opens, 

 the corolla is 12-16 mm. 

 long ; it elongates during 

 anthesis to 17-20 mm., 

 while the style elongates 

 but little. In this way 

 the stigma, which at first 

 projects beyond the 

 anthers, is brought into 

 contact with them, so 

 that automatic self- 

 pollination is inevitable. 



The plants examined by Lindman on the Dovrefjeld bore homogamous flowers, 

 the stigma and anthers of which matured in the bud. In this case, the end of the 

 style protrudes for a variable distance (1-5 mm.) from the corolla. The anthers are 

 generally enclosed in the flower, which is then dependent upon cross-pollination. 

 Sometimes, however, they grow out of the corolla, and the wind transfers the dry, 

 powdery pollen to the stigma. 



The flowers in Greenland were found by Warming to be feebly protogynous, 

 the anthers dehiscing soon after the maturation of the stigma. Both organs then 

 remain functional throughout anthesis. Warming also observed variations in the 

 length of the style, which sometimes projected far out of the flower, but was 



Fig. 316. Bartsia alpina, L. (after Herm. Muller). A. Flower seen 



from the side. B. Cross-section of do. on the line ab. C and D. Upper 

 and lower parts oi A, partly dissected (x 3 J). E. The two left anthers, seen 

 from their inner side. F. Entrance of the flower, seen directly from the 

 front. a, anthers; , entrance; /", filaments; gr, style; A, hairs; w, 



nectary ; ov, ovary ; st, stigma. 



