He adds: "En m?me temps, ce
mouvement d'?rection est accompang? d'un mouvement de torsion imprim? ? la
partie basilaire de la feuille, et pouvant souvent parcourir un arc de 90
degr?s." As the lower surfaces of the leaves are white, whilst the upper
are dark green, the tree presents a widely different appearance by day and
night. The leaves on a small tree in a pot did not exhibit with us any
nyctitropic movements. We have seen in a former chapter that the leaves of
Pinus pinaster and Austriaca are continually circumnutating.
MONOCOTYLEDONS.
Thalia dealbata (Cannaceae).--the leaves of this plant sleep by turning
vertically upwards; they are furnished with a well-developed pulvinus. It
is the only instance known to us of a very large leaf sleeping. The blade
of a young leaf, which was as yet only 13 1/4 inches in length and 6 ? in
breadth, formed at noon an angle with its tall petiole of 121o, and at
night stood vertically in a line with it, and so had risen 59o. The actual
distance travelled by the apex (as measured by an orthogonic tracing) of
another large leaf, between 7.
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