Botany; Geotropism; Plants -- Irritability and movements
Pinus austriaca.—Two leaves, 3 inches in length, but not
quite fully grown, produced by a lateral shoot, on a young tree 3 feet
in height, were observed during 29 h. (July 31st), in the same manner
as the leaves of the previous species. Both these leaves certainly
circumnutated, making within the above period two, or two and a half,
small, irregular ellipses.
(26.) Cycas pectinata (Cycadeæ, Fam. 224).—A young leaf, 11½ inches in
length, of which the leaflets had only recently become uncurled, was
observed during 47 h. 30 m. The main petiole was secured to a stick at
the base of the two terminal leaflets. To one of the latter, 3 3/4
inches in length, a filament was fixed; the leaflet was much bowed
downward, but as the terminal part was upturned, the filament projected
almost horizontally. The leaflet moved (see Fig. 114) largely and
periodically, for it fell until about 7 P.M. and rose during the night,
falling again next morning after 6.40 A.M. The descending lines are in
a marked manner zigzag, and so probably would have been the ascending
lines, if they had been traced throughout the night.
Fig. 114. Cycas pectinata: circumnutation of one of the terminal
leaflets, traced from 8.30 A.M. June 22nd to 8 A.M. June 24th. Apex of
leaflet 7 3/4 inches from the vertical glass, so tracing not greatly
magnified, and here reduced to one-third of original scale; temp.
19°–21° C.
CIRCUMNUTATION OF LEAVES: MONOCOTYLEDONS.
(27.) Canna Warscewiczii (Cannaceae, Fam. 2).—The movements of a young
leaf, 8 inches in length and 3½ in breadth, produced by a vigorous
young plant, were observed during 45 h. 50 m., as shown in Fig. 115.
The pot was slided about an inch to the right on the morning of the
11th, as a single figure would have been too complicated; but the two
figures are continuous in time. The movement is periodical, as the leaf
descended from the early morning until about 5 P.M., and ascended
during the rest of the evening and
part of the night. On the evening of the 11th it circumnutated on a
small scale for some time about the same spot.
Fig. 115. Canna Warscewiczii: circumnutation of leaf, traced (A) from
11.30 A.M. June 10th to 6.40 A.M. 11th; and (B) from 6.40 A.M. 11th to
8.40 A.M. 12th. Apex of leaf 9 inches from the vertical glass.
(28.) Iris pseudo-acorus (Irideae, Fam. 10).—The movements of a young
leaf, rising 13 inches above the water in which the plant grew, were
traced as shown in the figure (Fig. 116), during 27 h. 30 m. It
manifestly circumnutated, though only to a small extent. On the second
morning, between 6.40 A.M. and 2 P.M. (at which latter hour the figure
here given ends), the apex changed its course five times. During the
next 8 h. 40 m. it zigzagged much, and descended as far as the lowest
dot in the figure, making in its course two very small ellipses; but if
these lines had been added to the diagram it would have been too
complex.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account