COLOURS OF FLOWERS. 175 



Veitcli's fine Californian introductions. In this flower there 

 is no sign of blue. Yet, if there is a genns more pre- 

 eminently blue than any other cyanic race, it is surely 

 Delpliinium." 



It is true that some species have never yet transgressed 

 their bounds, so that Dahlias still refuse to be blue now as in 

 1845 ; and we are still ignorant of the reason. 



The effect of nutrition upon the colours of plants is well 

 known, in that they vary much more in a garden soil than 

 in the wild state ; and differ in colouring according to the 

 character and ingredients of the soil. Thus, as described by 

 a writer in Hovey's Magazine of Horticulture,* striped Dahlias 

 will be best kept clean by planting them in a poor soil, while 

 rich soil invariably runs them. E.g. B. var. striata formosis- 

 sima : No. 1 was planted in a poor gravelly soil, in an open 

 situation ; all the flowers but two were beautifully mottled. 

 No. 2 was planted upon a rich, cool, sandy loam ; not one- 

 half of the flowers were mottled. No. 3 consisted of three 

 plants, very highly enriched ; every bloom but one was self- 

 coloured. Similar effects follow on the variegated foliage of 

 Pelargoniums, according as they are grown in a too rich soil 

 or light one.f 



" Alum is said to render the Hydrangea blue ; and some 

 saline substances, such as phosphate of iron and muriate of 

 ammonia, appear to brighten the tint of red." J It often 

 happens, however, that blue and pink corymbs occur on the 

 same plant of Hydrangea. A cutting taken from a blue 

 Hydrangea growing at Southampton, and transferred to 

 Bedfont, changed to the usual colour on blooming tbere.§ 



Chloride of lime has been known to make a whole-coloured 



* Quoted in the Gard. Ohron., 1842, p. 8. 



t Gard. Chron., 1876, p. 567. J Ibid., 1843, p. 577. 



§ Ibid., 1886, vol. xxvi., p. 118. 



