538 



ANGIOSPERMAE—DICOTYLEDONES 



automatic self-pollination easily takes place. Schulz says that the corolla-tube of 

 hermaphrodite flowers is 2^-31 mm. long. Autumn flowers are self-fertilized, and do 

 not open. Schulz also observed gynomonoecism. Kirchner found the hermaphrodite 

 flowers to be homogamous. 



Visitors. — Herm. Muller supposed small Lepidoptera to be the poUinators of 

 the flowers, but these have not yet been observed, and the visitors of the inconspicuous 

 flowers are very few in number. Kirchner was fortunate enough to observe the 

 following. — 



A. Diptera. {a) Syrphidae: i. Eristalis tenax Z., freq. ; 2. Platycheirus 

 scutatus Mg., do. (1)) Muscidae : 3. Siphona cristata F. ; 4. Caenosia sp. ; 5. 

 Chlorops sp. B. Hymenoptera. Apidae : 6. Bombus agrorum F. C. Hemiptera. 

 7. Calocoris seticornis F. 



394. Asperula L. 



Flowers white, reddish, 3'ellow, or blue in colour ; arranged in cymose 

 inflorescences ; belonging to class C, or more rarely to L. 



1232. A. cynanchica L. (Herm. Muller, 'Fertilisation,' pp. 302-3, 'Weit. Beob.,' 

 Ill, pp. 72-3 ; Kerner, ' Nat. Hist. PI.,' Eng. Ed. i, II, p. 201 ; Schulz, ' Beitrage,' 

 I, p. 65; Loew, 'Bliitenbiol. Floristik.,' p. 394.) — The flowers are white or reddish 



'#'" \ 



Fig. I7g. Asperula cynanchica^ L. (after Herm. Muller). (i) Flower with pure white, smootli 

 petals, seen from above (>- 7). (2) Ditto, after removal of half the corolla; seen from the side. 

 (,^) Flower with rough petals ornamented with red lines ; seen from the side. (4) Ditto, seen from 



above, a, anther ; w, nectary ; oz\ ovary ; st, stipma. 



in colour, and Kerner says that they smell like vanilla. Hermann Muller describes 

 them as homogamous. The abundant nectar is concealed at the bottom of a 

 corolla-tube 2 mm. long. In the middle of this are situated the two closely apposed 

 capitate stigmas, while the converging anthers occupy the entrance to the flower. 

 Insect visitors are likely to eff'ect cross-pollination, for they usually touch the pollen 

 and stigma with opposite sides of their proboscis. Automatic self-pollination can 

 easily take place by the fall of pollen on the stigma. Hermann Muller was able to 

 distinguish two different forms of flower in Thuringia ; one with smooth, white, 

 moderately obtuse corolla-lobes, the other with these lobes rough on the upper 

 surface, ending in sharp recurved tips, and each marked with three red lines. Warnstorf 

 describes the pollen-grains, examined in water, as yellow in colour, small, spheroidal, 

 delicately striated, transparent, and about 25 /n in diameter. 



