PKOLIFICATION OF THE FLOWER. 131 



gated (fig. 64) after the fashion of Geum rivale, Ac* 

 Occasionally from the middle of the outer surface of the 

 urn-shaped thalamus proceeds a perfect leaf, which 

 could hardly be produced from the united sepals or 

 calyx-tube ; a similar occurrence in a pear is figured in 

 Keith's ' Physiological Botany,' plate ix, fig. 12. 



The change which the calyx undergoes when flowers 

 with an habitually adherent ovary become proHfied, and 

 wherein the calyx is disjoined from the ovary, has been 

 before mentioned, but it may also be stated that, under 

 such circumstances, the constituent sepals are frequently 

 separated one from the other, and not rarely assume 

 more or less of the appearance of leaves, as in pro- 

 Hferous flowers of UmibellifeToe^ Campanulac^cey Com- 

 positcE, &c. 



As to the corolla, it was long since noticed that 

 prolification was especially liable to occur in double 

 flowers ; indeed, Dr. Hill, who published a treatise on 

 this subject, setting forth the method of artificially 

 producing prolified flowers, deemed the doubling to be 

 an almost necessary precursor of prolification ;' but, 

 though frequently so, it is not invariably the case that 

 the flower so affected is double e. g. Geum. If double, 

 the doubling may arise from actual multiplication of 

 the petals, or from the substitution of petals for sta- 

 mens and pistils, according to the particular plant 

 affected. Occasionally in prohfied flowers the parts 

 of the corolla, like those of the calyx, become folia- 

 ceous, and in the case of proliferous pears fleshy and 

 succulent. There is in cultivation a kind of Cheiran- 

 thus? in which there is a constant repetition of the 

 calyx and corolla, conjoined with an entire absence of 

 the stamens and pistils; a short intemode separates 

 each flower from the one above it, and thus frequently 



' Bell Salter, ' Gard. Chion..' March 13tli. 1847. and ' Ann. Nat. Hist..* 

 1847. vol. xix, p. 471. Ac. 



* ' The Origin and Production of Proliferous Flowers, with the Cul- 

 ture at large for raising Double Flowers from Single, and Proliferous 

 from the Double.' By J. Hill, M.D. London. 1759. 



