The Washington times., 1901-08-04
SLUMBER IN PLANT LIFE.
Flowers and Trees Sleep as 10
Human Beings.
Naturalist of the Agricultural De-
pnrtment Explains This Remark
able Feature of Vegetable Exist
ence-The Functions of Leaves.

III ence-1he Functions of Leave
h One of the naturalists connected wit
: the Department of Agriculture is au
n thority for the statement that plant
q sleep almost as truly as do animals.
Perhaps the best marked form G
slumber in the vegetable world" thi
a gentleman said yesterday, lis that. O
= the great winter rest, when so man.
e species retire altogether under tn
t shelteIing soil and there lie dorman
side by side with the slumbering ami
> mails. OF course, we know that whel
: winter approaches the sick dormous
. retreats into his snug nook, a woveI
nest OF warm grasses. just above tn,
ground, where he dozes away the colo
r weather in state of, TO him, blissfu
Inconsistencies. Squirrels hibernate
in the holes of tree trunks, while bears
grow fat in autumn, and after sleep
ing the winter through emerge ir
April mere wasted shadows Of their
October selves. AS to the cold blooded
animals, such as nevis and Lizards,
snakes and adders, they dream away
the chilly months, like the Seven
Sleepers of Ephesus, coiied up in
tangles among banks and hedges. The
lesser creatures-snails and beetles and
| sruhs and so forth-hibernate under
ground or conceal themselves in the
crannies of rocks and walls. Now this
winter rest of animals does net differ
essentially from the winter rest of the
crocus or the hyacinth, which with
draw all the living material from their
leaves in autumn and bury themselves
inches deep in the soil in the shape OF
a bulb till February rains or April suns
| tempt leaves and flowers out again.
| THE whole vast class of bulbous and
tuberous plants, indeed-the lilies,
orchids, daffodils, narcissi, tulips,
squills, blue bells, and snowdrops-are
just alternating creatures which retire
underground in autumn with the slugs
and the queen wasps to reappear in
spring about the same time with the
return to upper air of the moles, the
tortoises, and the fritiliary butterflies.
But besides the yearly winter sleep
or Information, a great many plants
also sleep every night; in other words.
they suspend more or less their usual
activities and devote themselves TO
rest and recuperation. Look now at
this mimosa bush, wide awake of I
course. at this time of day, 1t, has,
you see, very compound leaf, split
up into four main parts or branches,
each of which is again subdivided into
many opposite pairs of leaflets. These |
11a,
and drinking for the benefit of the
plant. All the hundreds of the little
mouths of the leaflets are absorbing |
the carbonic acid of the surrounding
air, which is converted, under the in |
fuence of sunlight, into suitable plant !
food. This plant thus works for Its |
living in the daylight just as truly as
the busy bee when it gathers honey,
or as the aunt works when 1t collects |
dead meat and scraps of provender A
plant can only eat its proper food, car
bonic acid, when the light falls upon it;
at night it must sleep, digest, and dis
tribute what it has eaten. Should you
see this mimosa during the dark
hours you would see the main stems Of
4
direction, dropping downward, while
the branches of the four-fold leaves
hang close together instead of being
spread out fan-shape as now, the leaf
lets folded close to their stems Not
only the famous and well-known sensi-
tive plant sleeps like this, but also
many other kinds of mimosa and
acacia much cultivated ~ ]
houses. Il is pretty sight to see
them falling gradually asleep-dozing
off. If ] may be allowed the expression.
First of all the opposite pairs of leaf
cts fold together upward, SO as to pre-
sent a single combined surface, like !
hat of a hinged tablet when you shut
is halves together. Then the four
main leaf stalks on which the leaflets
ire fixed sink slowly down like sleep
ng child and double themselves away :
nut of the range of danger Last of all, !
he principal leaf stalk or main mid
ib Of the whole branch-like leaf itself ,
troops and drops drowsily and the en- {
ire structure hangs limp, as if dead, {
gainst the branch that supports it
THE machinery for producing these ,
urious sleep movements is situated in +
ertain very irritable little knobs at G
he base of the leaf stalk, one of which e
'ou can observe close to the stem here X
he mechanism acts much like a nerv- [
us system; 1T governs the movements
nd attitudes of the leaf by night or
ay. In the true sensitive plants the =
eafietS fold up out of harms way | y
'hen touched. In most minosas and !,
cacias, however, they only fold at i'
light or in very cold or dark weather. I
heir folding is partly effected for the {
AXE of warmth, because they then q
xpose only one surface of each leaf. n
All leaves go to sleep at night but
ONE very much more conspicuouslv s.
han others. The cases in which Won O
an actually see that they sleep are W
hose Of plants with thin and delicate s.
)liage, where the leaves or leaflets II
ain mutual protection against radia- -
ION and cold by putting themselves. ii
D to speak, two layers thick Very NJ
ainty spring foliage shows sleep most Il
bviously; very thick and coarse p
.aves. like those of the cyclamen the
the Siberian saxifrage. ID
r the common laurel, sleep without -
'lding: they have warmth enough or :,
assy covering enough to resist injury. u
ere again Is seen the analogy between al
lie nightly and the winter sleep: thin e'
aved trees shed their leaves in au- SO
INN, thick leaved kinds. such as II
linn