HABITS OF PLANTS. 289 



droops and dies. By ten o'clock the same night, it is totally 

 withered, to the great astonishment of the spectators, who flock 

 in crowds to see it. 



" The cereus, a native of Jamaica and Vera Cruz, expands 

 an exquisitely beautiful flower, and emits a highly fragrant 

 odour, for a few hours in the night, and then closes to open no 

 more. The flower is nearly a foot in diameter, the inside of 

 the calyx of a splendid yellow, and the numerous petals are 

 of a pure white. It begins to open about seven or eight 

 o'clock in the evening, and closes before sunrise in the 

 morning. 



" The flower of the dandelion possesses very peculiar means 

 of sheltering itself from the heat of the sun, as it closes entirely 

 whenever the heat becomes excessive. It has been observed 

 to open in summer at half an hour after five in the morning, 

 and to collect its petals towards the centre about nine o'clock."* 



Linnaeus has enumerated forty-six flowers which possess this 

 kind of sensibility : he divides them into three classes. 



1. Meteoric flowers, which less accurately observe the hour of 

 folding, but are expanded sooner or later, according to the 

 cloudiness, moisture, or pressure of the atmosphere. 



2. Tropical flowers, that open in the morning, and close before 

 evening every day, but the hour of their expanding becomes 

 earlier or later, as the length of the day increases or de- 

 creases. 



3. Equinoctial flowers, which open at a certain and exact hour 

 of the day, and for the most part close at another determi- 

 nate hour. 



LECTURE XLI. 



Habits of plants. Agents 'which affect their growth. Their 

 habitations, and geographical situations. Elevation corres- 

 ponding to latitude. 



THE constitution of plants and that of animals seems to fit 

 them for particular climates, and for digesting food of a certain 

 kind. The plant cannot, like the animal, rove about in search 

 of food best suited to its nature, but, fixed in one spot, must 

 receive the nourishment that there offers, itself. If this nou- 



* Bacon. 



Night- blooming Cereus, &c. Meteoric flowers Tropical Equinoctial 

 The constitution of plants fitted for particular climates. 



25 



