The Root Cause Of Our Deep South Texas Native Trees Surviving And Thriving
by K.C. Fletcher
published May 2018
The mostly hidden roots of our Mid-delta
Woodlands reveal adaptations over eons of natural
selection to resist local pests and diseases,
to live their life, while buried in the alkaline oftentimes
salty soil, baked by the sun above and
exposed to constant hot dry winds, combining
to cook these special trees along with their upland
heated habitat.
Specialized South Texas tree roots will survive
to sustain the above ground tree even
though those stressed, submerged roots are
temporarily deprived of oxygen. Too much
soggy soil for an extended period of time will
eventually drown our native Texas trees because
oxygen diffuses into the water-logged
soil 10,000 times slower. Rare occassions of
a rapid drop in temperature and a prolonged
freeze can also kill our Pharr Honey Mesquites
(Prosopis glandulosa).
Tree roots are responsible for the uptake and
delivery of the 15 mineral derived essential elements
mined from the surrounding soil, including
nitrogen gas from the atmosphere, which
is converted to root absorbable nitrogen compounds
by very special nitrogen-fixing bacteria
that live on and in the roots. The mesquite acts
as its own fertilizer factory and also allows absorbable
nitrogen to build up in the soil.
South Texas soil fungus attach to the mesquite's absorbing
root to feed off of the absorbing root's
sugars supplied by the leaves enhancing the
uptake of water increasing the chance of survival
for both biological buddies.
The leaf is the food factory for the entire tree
as carbon is combined with hydrogen to make
sugars that are transported throughout the tree
to supply energy for tree growth and maintenance
or stored as starch in the roots and elsewhere
within the tree.
The chemical energy trapped in the leaf-derived
sugar compounds is released by recombining
with oxygen, which is the definition of
respiration. All tree roots need to breathe oxygen
in order to power growth and maintenance
biochemical reactions.
All 28 species of deep South Texas, Tejanotough,
native trees rely on their woody roots, to
provide partial support and stabilization to the
trunk above ground and firm anchorage into
and onto the soil beneath.
The Mesquite tree wears the championship
crown for the deepest tap root growing to a
depth of 174 feet 10.4 inches straight down.
A Texas Honey Mesquite's highest leaves
reach an average height of 30 feet, up to 60 feet
if that lucky taller tree taps directly into a permanent
subterranean water supply.
Thusly, the
tap-rooted mesquite can extend below ground
around 3.25 times the tree's height. This accurately
measured fact is not just another traditional
Texas tall-tale. The mesquite coneshaped
tap root oftentimes grows to a larger
diameter than the above-ground trunk.
Think of that deep ground water traveling
the total possible 230 feet up through the roots,
trunk, branches and stems in order to quench
the constantly thirsty leaves, high above, manufacturing
the sugars and other nutritionally
needed compounds for those very roots, the
rest of that tree, for wildlife and ultimately,
even for the life of you and me.
Lateral roots growing outward on all sides
can extend radially 5-6 times the diameter of
the branches and leaves of the 30-60 foot wide
tree canopy and, especially the thicker primary
and secondary laterals in the mesquite, can be
bark-covered making it more like an underground
canopy, minus the leaves.
The mesquite's lateral roots radiate from the
root collar of the trunk with sinker roots growing
vertically from them. All act in concert
with the tap root to eliminate excessive wiggling,
twisting and bending of trunks caused by
our southeasterly wind gusts. Many non-native
trees never become anchored and suffer a deep
South Texas slow death by dehydration as the
wind bends and twists that tree, ripping absorbing
roots away from the soil particles thereafter
denying full water absorption capability.
The Texas Honey Mesquite has an amazing
ability to regenerate after complete separation
of the trunk, branches, twigs and leaves
aboveground. Any roots containing bud regeneration
zones that are present in the upper 6
inches of soil will regrow a brand new tree that
is usually multi-trunked.
When planting your next yard tree, if asked,
I shall enthusiastically root for the right native
tree to be planted in the right place at the right
time, every time!