2e Frangible Species Mandate
Alzate oversees roadside and median plantings for one-
lane roads up to six-lane highways; most of them are under
the jurisdiction of Broward County and/or the State, who
must approve everything she plants in these areas. The
medians of Coral Springs become increasingly narrow
with road expansion, making plant selection trickier.
In most cases, the County and State have mandated
that narrow medians be planted only with "frangible
species"—those that are sufficiently brittle that they
will readily break if a car hits the tree, thus preventing
car and driver from absorbing the shock of impact.
Solitaire palms (Ptychosperma elegans)—though not
trees, botanically speaking—are an example of a fran-
gible species. "They're skinny palms that would be
unlikely to fall over and kill a person," Alzate says. "We
do lose a lot of plant material including trees, palms, and
smaller vegetation due to accidents, especially because
so many people exceed the speed limit significantly."
bright in the cul-de-sacs, narrow corridors, and
in areas with conflicting overhead electric lines
of Coral Springs, where Alzate has been testing
them out. "They are exceptionally heat tolerant,
and they attract butterflies, birds, and bees," she
says. "The main challenge is finding them in the
quantity and quality you might ideally want."
Alzate says that the beautiful and more readily avail-
able
Eagleston hollies (Ilex × attenuata 'Eagleston'),
which can reach 20 to 25 feet (6.1 to 7.6 m), have
sailed through the worst of the heat. Eagleston
is a hybrid of the Florida native Dahoon holly
(Ilex cassine) and the native American holly (Ilex
opaca). Eagleston hollies reach only 6 to 10 feet
(1.8 to 3.0 m) wide so can be used in tight urban
spaces. They tolerate a variety of soil conditions.
Lastly, though flood tolerance is not necessary
for the trees of Coral Springs overall, there are
some medians that have retention zones, depres-
sions that collect water. "I mostly use bald cypress
(Taxodium distichum) there," Alzate says.
Median in major arterial road with crape
myrtles (Lagerstroemia indica).
Median in major arterial road with solitaire palms
(Ptychosperma elegans), a frangible species.
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