The Movements and Habits of Climbing Plants. Чарльз Дарвин

not being sufficient to hold the shoot to its place when the growing surface crept round to the opposite surface of the shoot; so that it was withdrawn at each revolution from its support.

      When a free shoot has grown far beyond its support, it sinks downwards from its weight, as already explained in the case of the Hop, with the revolving extremity turned upwards. If the support be not lofty, the shoot falls to the ground, and resting there, the extremity rises up. Sometimes several shoots, when flexible, twine together into a cable, and thus support one another. Single thin depending shoots, such as those of the Sollya Drummondii, will turn abruptly backwards and wind up on themselves. The greater number of the depending shoots, however, of one twining plant, the Hibbertia dentata, showed but little tendency to turn upwards. In other cases, as with the Cryptostegia grandiflora, several internodes which were at first flexible and revolved, if they did not succeed in twining round a support, become quite rigid, and supporting themselves upright, carried on their summits the younger revolving internodes.

      Here will be a convenient place to give a Table showing the direction and rate of movement of several twining plants, with a few appended remarks. These plants are arranged according to Lindley’s ‘Vegetable Kingdom’ of 1853; and they have been selected from all parts of the series so as to show that all kinds behave in a nearly uniform manner. [24]

      The Rate of Revolution of various Twining Plants.

      (Acotyledons.)

      Lygodium scandens (Polypodiaceæ) moves against the sun.

	H.	M.
June 18, 1st circle was made in	6	0
18, 2nd	6	15	(late in evening)
19, 3rd	5	32	(very hot day)
19, 4th	5	0	(very hot day)
20, 5th	6	0

      Lygodium articulatum moves against the sun.

	H.	M.
July 19, 1st circle was made in	16	30	(shoot very young)
20, 2nd	15	0
21, 3rd	8	0
22, 4th	10	30

      (Monocotyledons.)

      Ruscus androgynus (Liliaceæ), placed in the hot-house, moves against the sun.

	H.	M.
May 24, 1st circle was made in	6	14	(shoot very young)
25, 2nd	2	21
25, 3rd	3	37
25, 4th	3	22
26, 5th	2	50
27, 6th	3	52
27, 7th	4	11

      Asparagus (unnamed species from Kew) (Liliaceæ) moves against the sun, placed in hothouse.

	H.	M.
Dec. 26, 1st circle was made in	5	0
27, 2nd	5	40

      Tamus communis (Dioscoreaceæ). A young shoot from a tuber in a pot placed in the greenhouse: follows the sun.

	H.	M.
July, 7, 1st circle was made in	3	10
7, 2nd	2	38
8, 3rd	3	5
8, 4th	2	56
8, 5th	2	30
8, 6th	2	30

      Lapagerea rosea (Philesiaceæ), in greenhouse, follows the sun.

	H.	M.
March 9, 1st circle was made in	26	15	(shoot young)
10, semicircle	8	15
11, 2nd circle	11	0
12, 3rd	15	30
13, 4th	14 Скачать книгу В начало < 1 2 3 4 5 6 7 8 9 > В конец