DIAL OF FLOWERS. 
355 
open all night, probably because their delicate 
organs would be injured by the sun. The 
CEnotheras, the Gauras, and the different spe¬ 
cies of the Mirabilis, furnish examples of this 
kind.' Thus too the Cactus opuntia opens its 
magnificent blossoms at night only, and towards 
morning shuts them up for ever. The flowers 
of many plants of the nineteenth class are ob¬ 
served to hang their heads during night—the 
Camellia, for example—by which means the 
rain, or dew, which might injure the tender 
organs of fructification, can run off the more 
easily. In other plants of this class, the flower 
shuts up against rain, and on the approach of 
evening, as is the case with the Marigolds. 
The periodical change of colour in some 
flowers is also worthy of remark. Thus the 
flowers of the speckled French Honeysuckle 
(Hedysarum maculatum') are purple in the 
morning and green at noon. The changeable 
Hibiscus (Hibiscus mutabilis) is white in the 
morning, flesh-coloured at noon, and rose-red 
in the evening. Thus, too, the great Corn-flag 
(Gludiolus grandis) changes its colour several 
times in the course of the day. 
