THE WONDERS OF VEGETATION. 269 



A great number of flowers open only at night. 

 Among the most remarkable of these is the large 

 flowered cactus (Cactus grandiflorus) or, night- 

 blooming cereus, originally from Jamaica and Vera 

 Cruz. Its magn ill cent flower expands and diffuses 

 a delicious perfume soon after sunset ; but it remains 

 open only a few hours, and before dawn breaks it has 

 closed. Generally it expands once more on the fol- 

 lowing evening, and this continues during several 

 days. For four years in succession a plant of this spe- 

 cies opened its flowers in a garden in the Faubourg 

 St. Antoine, on the 15th July at seven o'clock in 

 the evening, with unfailing regularity. 



Among the flowers which open and diffuse their 

 perfume only at night we may mention the Arabian 

 jessamine, several species of the Oestrum cenothera, 

 the lychnis, several libnes, some geraniums, and a vari- 

 ety of gladiolus. The Belles de Nuit, our marvel 

 of Peru (Mirabilis Jalapa\ owe their French name to 

 this habit of not opening till evening in hot weather. 



The African marigold opens constantly at seven 

 o'clock and remains open until four o'clock, if the 

 weather be fair. If it does not open, or if it close 

 before that hour, it is certain that rain wil] fall dur- 

 ing the day. In like manner the Siberian thistle 

 remains open all night, unless it is going to rain the 

 following day. 



The flowers of the nymphsea or water-lily, close 

 and sink into the water precisely at sunset ; they rise 

 again to the surface and expand as soon as the sun 

 reappears. Pliny jnentions this fact : " It is re- 





