H.   M.
June 13, 1st circle was made in         1   45
     13, 2nd                            1   17
     14, 3rd                            1   36
     14, 4th                            1   59
     14, 5th                            2    3

Siphomeris or Lecontea (unnamed sp.) (Cinchonaceae) follows the sun.

                                       H.  M.
                                              {(shoot extremely
May 25, semicircle was made in         10  27 { young)
    26, 1st circle                     10  15 (shoot still young)
    30, 2nd                             8  55
June 2, 3rd                             8  11
     6, 4th                             6   8
                                              { Taken from the
     8, 5th                             7  20 { hothouse, and
     9, 6th                             8  36 { placed in a room
                                              { in my house.

Manettia bicolor (Cinchonaceae), young plant, follows the sun.

                                        H.  M.
July 7, 1st circle was made in          6   18
     8, 2nd                             6   53
     9, 3rd                             6   30

Lonicera brachypoda (Caprifoliaceae) follows the sun, kept in a warm room in the house.

                                       H.   M.
April, 1st circle was made in           9   10 (about)
                                               {(a distinct shoot,
very
April, 2nd circle was made in          12   20 { young, on same
plant)
       3rd                              7   30
                                               {In this latter
circle,
                                               { the semicircle from
                                               { the light took 5
hrs.
       4th                              8    0 { 23 m., and to the
                                               { light 2 hrs. 37
min.:
                                               { difference 2 hrs
46m.

Aristolochia gigas (Aristolochiaceae) moves against the sun.

                                       H.   M.
 July 22, 1st circle was made in        8    0 (rather young shoot)
     23, 2nd                            7   15
     24, 3rd                            5    0 (about)

In the foregoing Table, which includes twining plants belonging to widely different orders, we see that the rate at which growth travels or circulates round the axis (on which the revolving movement depends), differs much. As long as a plant remains under the same conditions, the rate is often remarkably uniform, as with the Hop, Mikania, Phaseolus, &c. The Scyphanthus made one revolution in 1 hr. 17 m., and this is the quickest rate observed by me; but we shall hereafter see a tendril-bearing Passiflora revolving more rapidly. A shoot of the Akebia quinata made a revolution in 1 hr. 30 m., and three revolutions at the average rate of 1 hr. 38 m.; a Convolvulus made two revolutions at the average of 1 hr. 42 m., and Phaseolus vulgaris three at the average of 1 hr. 57 m. On the other hand, some plants take 24 hrs. for a single revolution, and the Adhadota sometimes required 48 hrs.; yet this latter plant is an efficient twiner. Species of the same genus move at different rates. The rate does not seem governed by the thickness of the shoots: those of the Sollya are as thin and flexible as string, but move more slowly than the thick and fleshy shoots of the Ruscus, which seem little fitted for movement of any kind. The shoots of the Wistaria, which become woody, move faster than those of the herbaceous Ipomoea or Thunbergia.

We know that the internodes, whilst still very young, do not acquire their proper rate of movement; hence the several shoots on the same plant may sometimes be seen revolving at different rates. The two or three, or even more, internodes which are first formed above the cotyledons, or above the root-stock of a perennial plant, do not move; they can support themselves, and nothing superfluous is granted.

The Movements and Habits of Climbing Plants Page 13

Charles Darwin

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Charles Darwin

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