The Bossier banner. [volume] (Bellevue, Bossier Parish, La.) 1859-1952, 1881-09-08
Flower Clocks and Barometers.

Even the most casual observer of ma
ture must have noticed the closing of
certain flowers upon the partial or en-
| tire withdrawal of light. Thus the
| chickweed is sensitive to cloudy wealth
er and acts almost as barometer, and
every one knows the action of the
".pimpernel,' or poor-man's weather
glass, Anagatlts a'Vensis, L. This
pretty little plant is frequent on New
port Island, where | have found 1T, es-
pecially on the cliffs beyond the first
beach. 1t is adventitious from Europe.
Tennyson. who is an acute observer,
says of it: "The pimpernel dozed on
the lea. The well-known "Marvel of
Peru" is also called -Four O clock :"
from its habit of opening about that
hour. If we watch any plant we shall
ind that it has a pretty definite time
OF expanding or closing its petals, as
well as particular way of doing it.
Botanists, then, speak of the waking
and sleeping conditions of the plant and
much research has been bestowed upon
the subject in order to find out the phys
ical action and cause of the phenomena.
In his recent volume on Movement in
Plants Mr.. Darwin gives the results of
his painstaking Investigations of this
and kindred subjects. As generally
happens in his work, while he is stead
lily aiming at some particular point, he
disposes of any quantity of obscurities,
as side issues, on the way.
Linnaus, noting the precise times of
opening and closing of flowers. con-
structed a floral clock in his gardens at
Upsat, where the hours were indicated
by the conditions of different plants.
Afterward DeCandolle did the same for
the latitude of Paris. The clock of
Linnnus in Sweden runs slower than
that of DeCandolle in France. Climate
as well as latitude. and particular sea-
sons also, would influence this sensitive
horolog. Those interested will find
DeCandolle's list given in Figuier's Veg
etable World, American edition, page
134.
Of few familiar plants the hours of
opening are about as follows: Morning
glory, to 4 a. M; pimpernel, s TO 10
a. M; marvel of Peru, 4 to p. M.
evening primrose, 5 to p. m.; night
blooming cereus, Z to s p. m.
Thus in each flower and simple bell,
That in our path betrodden lie,
Are sweet remembrancerS who tell
How fast the winged moments Hy.''
The hours of closing are as definite as
those of opening, and thus we may ar
range quite dial, the hours being in
dicated by particular plants. The plants
may be confused by means of artificial
light, but upon withdrawal of the un-
natural conditions, will sooner or later,
resume their normal record
1t is curious to watch the different
attitudes flowers assume in repose. In
the botanic garden in Cambridge the
writer used to 60 out toward evening to
watch the changes. The movements
are sometimes very quick, especially
those of the foliage, which also has its
time of sleep. Thus in the little Mar
silia, a water-plant, with four obcor-
date leaflets, these turn in upon each
other from the expanded condition, so
as to meet face to face. There is quite
perceptible little "click" when the
movement occurs. The petals of some
plants droop in slumber, others fold
crossways; still others curl up length
wise. So with the rayfiorets of the
Composite. The whole aspect of gar
den is. hence, quite changed in the
evening. In fact, it does not do to al
low our Investigations to cease with the
daylight. ht.-ProUtdence (R. IT, Star.
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