How a Tree Works – Family Plot

We’re at the Memphis
Botanic Garden in front of this water oak. It’s a huge water oak. And we’re gonna learn
about tree physiology. – Yes. – This is the question
we usually get: “What is photosynthesis though? How does that work?” – Photosynthesis is
where the tree’s leaves absorb the sunlight and
produce these carbohydrates and sugars and
provides the energy and the food for the tree. – So it’s all about energy
and food for the tree. – It’s all about
energy and food. – Okay. Now, it’s been hot here lately. – Yes. – What about respiration though? – Respiration is the
process where the tree uses that energy that’s
produced by the leaves, but when it gets
over 92, 93 degrees the trees have
cells that shut down the process of
that photosynthesis that helps that tree
maintain and retain the energy that has been
already produced by the leaves. – Okay, which is real important. ‘Cause it has been above
in the 92, 93 degrees. All right, now let’s talk
about the different layers of a tree, let’s talk about
the xylem and the phloem. So let’s start with the xylem. – Okay, the xylem
works like with osmosis and that is on the interior
part of the cambium, and it pulls the water and
the minerals from the soil and takes it up
through the tree all the way up to the
tips of the leaves. It goes through the
transpiration process where that moisture
and water is released through the pores of the leaf. – Okay, and what
about the phloem? – The phloem tissue is the
vascular section of the tree that takes that energy
that’s produced by the leaves and pulls it out
through the tree and disperses it throughout
the tree’s parts. – Okay, so that flows
in both directions. – Flows in two
directions, yes, or three. – Or three? – Yes, you have the
rays of the wood, which run from the
interior part of the tree outwards to the
where the sapwood is and that carries the nutrients
radially to the sapwood. Here we have, Chris,
a slab of wood, this is a piece of red oak and just to describe some
of the physiological aspects of this piece of
wood, or this red oak, we have the vascular tissue is made up of four different
parts or more actually, but to simplify it, the
bark, phloem, cambium, and xylem tissue. Phloem to the outside,
cambium in the center, the xylem to the inside. The bark is to protect all
the other vascular tissue. – All right. – The phloem tissue is
what brings the nutrients through the tree and
disperses it from the leaves, then the cambium
produces both the phloem and the xylem
tissue as it grows, and the xylem tissue
brings the nutrients up from the root system
up throughout the tree. – Okay. – Now, the rays, you see
the small lines right here? Running through there? – Yeah. – Those are your rays, yes,
they’re very pronounced, especially when the
wood is dried up some. – Okay. – And these are
your growth rings, so as the tree grows it
produces an annual growth ring, early wood and late wood. Now the rays
transports nutrients into the sapwood area,
which is out here. Now the unique thing about
this functioning tissue is all this wood that you see
in here is non-conductive, it’s just there for the support
that I mentioned earlier. Your productive and
conductive tissue or phloem and xylem
tissue is only on the outermost part of
the tree, right there. That’s why a tree can be hollow and still function,
just like a solid tree. And then of course
you’ll have places where insects will
live in there, and the tree will
compartmentalize over that. But all through here
you have the cells that divide when a tree
is wounded like that, the cells, the parenchyma cells would divide and
create new tissue and compartmentalize
over the wound. That’s how all this functions. The xylem tissue has
the parenchyma cells that do that division. – That’s pretty good. – That’s how trees heal. When a tree gets wounded,
the wound is permanent. When we cut ourself, we heal, but it’s the same
cell system that heals both our cut on our hand
and the wound on the tree. It’s the parenchyma cells. It’s closely related to
how our bodies function. It’s a living organism. – Now let’s talk about
the roots though. What do we need to know
about the roots of the tree? – Roots are very important, however there’s
trees that blow over. A tree can survive without
having a complete set of roots because of the energy that
the leaves can produce for it. So the roots function as
anchorage to the ground, storage for what’s
produced by the leaves and anchored, just anchored, in case it anchored
to the ground. When you see a tree blow over, you’ll notice that
there might be one root and the rest of
the roots are dead. It didn’t have anything to
anchor it to the ground. – How about that. You know, most people
think that tree roots grow deep, deep, deep
down into the ground. That’s not the
case though right? – When they’re young,
they’ll have a tap root. That tap root will
either turn and go out and become part of the
lateral root system or it just dies off. It can’t function
properly, it can’t survive unless there’s water down there. Like a spring, well
or something down low that it can get
nutrients and water from. – Okay, now what about
the little tiny roots, the little fan roots that are
right there at the surface? – Fibrous roots? – Yeah the fibrous roots. – Or the hair roots,
or the feeder roots. They got different
names for ’em. They’re very fine,
kind of like our hair. – Okay. – About like that,
and they absorb the moisture or the
water, available water and that leads it all the
way up throughout the tree. – So that’s pretty
much their function. – They’re feeder roots, yeah. – They’re just feeder roots. They just feed the tree. Now this time of the year
we get a lot of questions about, “Ah, the leaves are
falling off my tree so early.” Why is that? – Because there’s not any
available water in the soil, and so the tree’s
saying I need to stop using up the energy
that I’ve produced so far and get rid of
some of these leaves so I can start to rest and get myself ready
for the winter. It’s just premature leaf drop. – And I’m about to get to that because we’ve had a
lot of hot weather, so does that amplify
what we’re seeing? – Yes, it does,
especially when the soil is dry now, as it is, and I mentioned the
transpiration process stopping because of the temperature. Yeah, it all ties together. – Should we water trees? – Yes, yes. – How much would you water
a big tree like this? – Oh my goodness,
a tree this size can probably, if it’s available, pull up 150 gallons a day if it has the root system to. And remember I mentioned
that transpiration. You know, where’s that water go? It goes throughout the
tree, it’s a big tree. If it’s able to transpire, it leaves the tree through
the pores on the leaves. – Through the pores
on the leaves. – On the underside. – That has to do
with what, stomates? – Stomates, yep. – Something like that, definitely would be
some simple biology. – And the guard cells are
what close the stomates to prevent them from
losing all their water that they’ve taken up
during these hot days. – Okay, now when
you’re watering a tree, I mean should you
use a soaker hose– – Soaker hose is good. – How would you go about adding water in it? – I have a Ross deep
root waterer in my house. That way I can turn the water on and it’s a long tube, attaches to the water
hose, and I work that probe down into the ground
with that water, so I’m creating more
air space in the soil and I’m getting that
water down deeper. When this ground is
really compacted, sometimes that water
doesn’t percolate down through the soil, so. But other than that, a
soaker hose to me is best, because that water that
flies through the air and it hits the ground,
it compacts the soil. – It compacts the soil. – That upper layer
of soil, yeah. – Okay, when is the best
time to plant a tree? How about that one? – I prefer the winter. – So you prefer the winter. – Late fall. – Why’s that? – Or early spring. The temperature’s
not quite so high, and the tree can rest
through the winter, as long as you put
proper mulch on it. We have some trees
we need to get into the ground this October. Sometimes it’s a
matter of timing, sometimes the weather’s not
real good in deep winter but yeah, fall,
winter, early spring. – Early spring, what would
be the best time to do that? – Some people are
planting trees right now. I don’t recommend it. It’s just too hot. – Yeah, it is hot. – But a landscaper’s
gotta stay busy. – Yeah, yeah, that’s for sure. Well look, we do appreciate
all your valuable information that you have about trees. – Sure, glad to be here.


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