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LEA\'ES CIIANGE COLOR II{ THE
FALL?
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We all enjoy the beautiful show of colors as leaves change each autumn. Did you ever wonder how and
why this happens. To ansxer that questio4 we.fust haVe to understand what leaves are and what they do.
Leaves are nature's food factories. Piants take water from the ground through their roots. They take a gas
called garbon dioxide from the air. Plants use sunlight to turn water and carbon dioxide into glucose.
Glucose is a kind of sugar. Plants use glucose as food for energy and as a building block for growing. The
way plants turn water and carbon dioxide into zugar is called photosynthesis. That means "pu@rg
together with light." A phemical called chlorophyll helps make photosynthesis happen. Chlorophyll is
- what gives plants their green color.
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GLUCOSE
As summer ends and auhrmn comes, the days get shorter and
shorter. This is how.the trees ,,know,, to
there.is
**gh liqll orwater for photosynthesis. The trees will res! and Iive offthe
food they stored during the summer. fn.y b"gi, to ,h,rt down
their food-making
gr;"n
chlorophyll disappears from the leaves. As th;bright green
fades away, we begin to see yellow and
orange colors. Smdl amounts ofthese.colors havJb"* in
the leaves at aongir"G-C'";1
vJsra vcu' L ]sE
*-,1,-.,
trrtr! i,
the summer, because thgy are covered up by. the green
Put"g winter,
Y
A"".i*.ii.
chroioptry[
.
The bright reds and purples we see in Ieaves are made
mostly in the fall. h some trees, like maples;
gJycog is trapped in the
after photoslmthesis
irrrieht and the cool nights of autumn turn
leavgs
this glucose into a red color- The brown collr oftrees
""pr.
like oaks is made from wastes left in the leaves.
It
is the combinatio4 of all these things that make the
beautiful colors we enjoy in the fall.
HOW PLAI'{TS PREPARE FOR WIr{TER
ofliquid water, prants are busl'riieking
*'m:Xf
and storing food, *:'=.}|:'"::H+:11
and growing. But w.hat about *int..rirlr"t
The days .r. *r.i,iironilijil;j;
-l*:"9.ftp}
to get- Plants have found many different ways to get through tle trarsh days
oiwinter.
\y
SoTe.plants, including many gardelflowers, are called "annuals," which
means they complete their life
cycle in one growing se,rson. They die when winter @mes, but their seeds
rernairg ready to sprout again
in thespring. "Perennials" Iive for more than two years. This cate-qory includes
trees and shrubs, as well
as herbaceous plants with soft, fleshy stems. When winter
*ooay p"n;;f
shrubs can
survive the cold' The above ground parts of herbaceous plants (leaves. stalliti
rlaff die off but
*r.r,ih.
";;;d
food untit
'oE-ru-rs.
plantl grow, they shed older leaves and grow new ones. This is important
because the Ieaves become
$
damaged over time by insects,
,-
disease and weather. The shedding and replacement continues
all the time.
In additila decidtous trees, Iike maples, oaks and elms, shed all their leaves
in the fall in preparation for
winter. "Evergreens" keep most of their leaves during the winter. They have
rpr.irt t.uuei iesistant to
cold and moiiture loss. stmq r*e pi"e a"J fi.;;;;fave lon! thin nJ"Jr.r.
others, like holty, have
broad leaves with tough, w&ry surfaces. on very .oid, dry d";r,-il;;i."r",
sometimes curl up to reduce
their exposed surface. Evergreens may continue to photosyntt..ir" during
the winter as long as they get
-l
enough water, but the reaotions occur more slowlylt coldlr temperatures.
puring $Itrrmer dayq leaves make more glucose than the plant needs
for energy and growth. The excess
i.s tumed into starch and stored until neeJed.
As rrr" a"rritrr, gets shorter i, ,i" autumn, plants
begin to
shut down their food production
Ma'y
changes occur in the leaves bf deciduous trees
before- they finally fall from the branch.
The leaf has
actually been preparing for autumn since it started
to gro* in the spring. At the base of each leaf
is a
special layer of cells called the "abscission" or."prr",iln
layer Ax'Jril;;, small tubes which pass
throueh this laver carry water into the leaq ald fb;Jr;.k
to the tree. In the fall, the cells of the
-abscisiion lavei been io ,*.u
redr.rcing and finairy cuffing offflow
between leaf and tree' Glucose and waste products
are t
in theieaf without fresh water to renew
it, chlorophyll begins to disappear.
"pp"a
*; f#;ffi-rtffi;:lta!
other colors' which have been there all
thea become visible. The orange corors
come from carotene
('kar-uh-teen) and the yellows from xanthop[yll
They urr.rr*on pigmenrs, arso found in
ft;-td-fiJ).
flowers' and foods like carrots, bananas
aa .gg you.r.-w" do not tno* ii.i..*.., role in leaves, but
scientists think they may be invorved ro*"rroil'
pt otoryntrr"rir.
{*g
The bright'red and purple colors comeaom
Tft*yT*n (an-thuh-'si-uh-nuhn) pigments. These are also
common in plants; for example, beets, .ea apples,
grapes, and flowers Iike violets and
hyacinths' In the leaves, theie pigments are
io.*ra i" tI" lut mn from trappd glucose. Brown
colors
a bitter waste product. Ditrerent rl"ruir"ri"*;f
rh.;;;i;ents give us a wide ranse
eIq*r"
!!}]*:T":Hffi
As the bottom cells in the-ySaration layer form
a seal between leaf and treg the cells in
the top ofthe
separation layer begin to disintegrate. They
*a evenn aly iir. r"*i, blown away or
f."";;;-un",
i3p9*T'..question remains. What causes the most
spectacular display? The best place in
9:,r:'.t
world foi viewing fall colors is probabty
the
trre
ea*ii ilil;
states. rnis is bJcause of the crimate
and the wide variety of deciduous trees-rhe
urishtesi"o-G are seen when late summer is dry there,
and
aytumn has bright sunny days and cool (low
+o'irunr"J"iil
ma.ke a lot of anthocyanin
cleudv davs and wann nights uri"gs aiau"ieh1r.
Jolors.
**
:ffin,fi,H
il,";'"*;
a"J*-.*ry
aost quickry ends the
JI
." , =*"t
.
SIHYDO IEA\IES CHANGE COLOR,S IN THE FALL
r
QUESTTONS
tne information given to you about leaves changing color in the frtl, and answer the
following questions. Idake sure your a$;wers are corylete and neat.
neit
1.
Wbat isphotoqmthesis?
,,
What is the pigment in th€ chloroplast that glv.es plants their gr.een color?
1-
How do trees'*nouf to begin getting ready for winter?
j
Wbat makes l15; see the pretty yellow and orange colors in the leaves?
5. What makes the red colorof leaves we see inthe frll?
6.
What'makes leaves look brown?
7.
What is the difference between amuals and perennials?
8. $ow
do eyergreelxi aad deciduous trees differ?
9. During surDrner days, leaves make more glucose than the plant needs for energy and grourtiWhat do the plants do withthe excess glucose?
U
I0. Describe some changes that occrr in the leaves of deciduous trees before they frnally
from the branch-
frh
fall, the cells ofthe abscission layer begin to srell and cut offflow between the leaf
and tree. No Aesh water is able to reachthe teaq and aheady made glucose and waste
products become trapped in the leaf Without fiesh water, chlorophyll begins to disappear.
Now, other colors become visible.
Orange colors come ftom
Yellows come from _
Both ofthese colors are common in flowers end foods like:
,
, and
11. In the
.}
a
o
,
Bright red and purple colors come from
forgd?
. In what foods are tlese commonly
12. What is the best place inthe world to viewthe beautiful drsplay of colors?
I3. $/hy?
14. Whenwould you
see the
brightest colors? What kind ofFall would brig about drab colors?