60 PLANTS FOR WINDOW GARDENING. 



the varieties, we believe, are readily propagated by cuttings, 

 and many produce seed in abundance. Some succeed better 

 if allowed to trail on the ground ; others are so delicate as 

 to need constant attention and careful training. Some are 

 hardy in England, though to our knowledge none have ever 

 been able to survive our severe winters in the open ground, 

 or protected in frames. All the varieties are of the most 

 rapid growth, and are mostly free flowerers ; none are desti- 

 tute of some beauty, while the greater number are remark- 

 able for the combinations of dazzling colors which they 

 afford. The prevailing color is yellow in its different 

 shades ; next, red ; then dark ; and lastly, a most extraor- 

 dinary fact, which puzzled the botanists, a beautiful blue. 

 It had been asserted and argued, with great show of reason, 

 that a flower, of which all the known varieties, or the gen- 

 eral types, were of red, yellow, or cognate colors, could, by 

 no possibility, be found related to a plant with blue flowers, 

 or could there be a blue flowering plant in the same class. 

 The discovery of a blue tropreolum, in 1844, completely 

 refuted this theory. In the treatment of tne tropaeolum, it 

 is essential for the good health of the plants that they 

 should enjoy plenty of light and air ; without this, they can- 

 not fail to become sickly or unsightly from faded leaves and 



