CAMPANULA CEAE 



19 



Conspicuousness is greatly enhanced by aggregation of the usually blue or violet 

 flowers into rounded, ovoid, or elongated heads, and the frequency of insect-visits 

 is generally proportional to the size of the heads. 



Kirchner (Jahreshefte Ver. Natk., Stuttgart, liii, 1897, pp. 219-20) has empha- 

 sized the fact that the above description, abstracted from Hermann Miiller, only 

 applies to species belonging to the section Hedranthum G. Don, in which the flowers 

 are sessile and the corolla-lobes gradually become separate from base to tip in the 

 course of anthesis. The flowers of the section Synotoma G. Don are also social. 



FIG. 213. PhyteuTfta, L. (after Herm. Muller). A. Young flower-bud of Phyteuma Michelii, after 

 removal of the corolla and one stamen. B. Flower in the first (male) stag-e. C. Ditto, in the second 



(female) stage (X 7). a, anthers; ca, calyx; co, corolla ;yA, stylar brush (sweeping-hairs) ; ^, filaments ; 

 p, corolla-lobes ; po, pollen ; s, teeth of calyx ; sd, nectar-covers ; si, stigmas. 



In the sub-genera Podanthum Boiss., Petromarula Veni., and Cylindrocarpa Regel, 

 the inflorescences are panicles or racemes, so that their flowers differ very essentially 

 in form and mechanism from those which are more closely associated. This is the 

 case, for instance, with the next species. 



1737. P. canescens Waldst. et Kit. (Kirchner, op. cit., pp. 219-20.) This 

 species belongs to the section Podanthum. Kirchner has investigated it in the 

 Hohenheim Botanic Garden. The flowers are arranged in a long loose raceme, 

 and their mechanism is closely related to that of Campanula. The calyx-teeth are 

 green in colour, subulate, and 5 mm. in length. The five (sometimes four) petals 

 are 10-15 "im. long, and 2-2^ mm. broad, and scarcely united at their bases. They 

 diverge almost in the same plane to form a star about 20 mm. in diameter, and are 

 violet in colour with a whitish base, and traversed by a darker median streak. The 



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