gyrans, and it seems
only occasionally to bear rudimentary lateral leaflets. Duchartre,
'El?ments de Botanique,' 1867, p. 353.
[page 365]
Mimosa the pulvinus has been greatly reduced, we do not know. Nevertheless,
it deserves notice that the reduction of the leaflets in these two genera
has apparently been effected by a different process and for a different
end; for with the Mimosa the reduction of the inner and basal leaflets was
necessary from the want of space; but no such necessity exists with
Desmodium, and the reduction of its lateral leaflets seems to have been due
to the principle of compensation, in consequence of the great size of the
terminal leaflet.
Uraria (Tribe 6) and Centrosema (Tribe 8).--The leaflets of Uraria lagopus
and the leaves of a Centrosema from Brazil both sink vertically down at
night. In the latter plant the petiole at the same time rose 16 1/2o.
Amphicarpoea monoica (Tribe 8).--The leaflets sink down vertically at
night, and the petioles likewise fall considerably.
Fig. 151. Amphicarpoea monoica: circumnutation and nyctitropic movement of
leaf during 48 h.
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