Besides affording prognostics, many plants also fold themselves up at particular hours, with such regularity, as to have acquired particular names from this property. The following are among the more remarkable plants of this description:—
Goatsbeard.—The flowers of both species of tragopogon open in the morning at the approach of the sun, and without regard to the state of the weather regularly shut about noon. Hence it is generally known in the country by the name of go to bed at noon.
The princesses’ leaf, or four o’clock flower, in the Malay Islands, is an elegant shrub so called by the natives, because their ladies are fond of the grateful odour of its white leaves. It takes its generic name from its quality of opening its flowers at four in the evening, and not closing them in the morning till the same hour returns, when they again expand in the evening at the same hour. Many people transplant them from the woods into their gardens, and use them as a dial or a clock, especially in cloudy weather.
The evening primrose is well known from its remarkable properties of regularly shutting with a loud popping noise, about sunset in the evening, and opening at sunrise in the morning. After six o’clock, these flowers regularly report the approach of night.
The tamarind tree parkinsonia, the nipplewort lapsana communis, the water lily nymphaea, the marygolds calendulae, the bastard sensitive plant aeschynomene, and several others of the diadelphia class, in serene weather, expand their leaves in the daytime, and contract them during the night. According to some botanists, the tamarind-tree enfolds within its leaves the flowers or fruit every night, in order to guard them from cold or rain.
The flower of the garden lettuce, which is in a vertical plane, opens at seven o’clock, and shuts at ten.
A species of serpentine aloe, without prickles, whose large and beautiful flowers exhale a strong odour of the vanilla during the time of its expansion, which is very short, is cultivated in the imperial garden at Paris. It does not blow till towards the month of July, and about five o’clock in the evening, at which time it gradually opens its petals, expands them, 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 cerea, a native of Jamaica and Vera Cruz, expands an exquisitely beautiful coral 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.
Linnæus 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 decreases. 3. Equinoctial flowers, which open at a certain and exact hour of the day, and for the most part close at another determinate hour.