Botany; Geotropism; Plants -- Irritability and movements
Securigera coronilla (Tribe 4).—The leaflets, which stand opposite one
another and are numerous, rise up at night, come into close contact,
and bend backwards at a moderate angle towards the base of the petiole.
Fig. 144. Trifolium repens: circumnutation and nyctitropic movements of
a nearly full-grown terminal leaflet, traced on a vertical glass from 7
A.M. Sept. 30th to 8 A.M. Oct. 1st. Nocturnal course, represented by
curved broken line, much abbreviated.
Lotus (Tribe 4).—The nyctitropic movements of 10 species in this genus
were observed, and found to be the same. The main petiole rises a
little at night, and the three leaflets rise till they become vertical,
and at the same time approach each other. This was conspicuous with L.
Jacoboeus, in which the leaflets are almost linear. In most of the
species the leaflets rise so much as to press against the stem, and not
rarely they become inclined a little inwards with their lower surfaces
exposed obliquely to the zenith. This was clearly the case with L.
major, as its petioles are unusually long, and the leaflets are thus
enabled to bend further inwards. The young leaves on the summits of the
stems close up at night so much, as often to resemble large buds. The
stipule-like leaflets, which are often of large size, rise up like the
other leaflets, and press against the stem (Fig. 145). All the leaflets
of L. Gebelii, and probably of the other species, are provided at their
bases with distinct pulvini, of a yellowish colour, and formed of very
small cells. The circumnutation of a terminal leaflet of L. peregrinus
(with the stem secured) was traced during two days, but the movement
was so simple that it is not worth while to give the diagram. The
leaflet fell slowly from the early morning till about 1 P.M. It then
rose gradually at first, but rapidly late in the evening. It
occasionally stood still for about 20 m. during the day, and sometimes
zigzagged a little. The movement of one of the basal, stipule-like
leaflets was likewise traced in the same manner and at the same time,
and its course was closely similar to that of the terminal leaflet.
Fig. 145. Lotus Creticus: A, stem with leaves awake during the day; B,
with leaves asleep at night. SS, stipule-like leaflets.
Public-domain text, read in full here on John Shaqi.
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