of drought tolerant plants
Michael V. Mickelbart, Department of Horticulture
& Landscape Architecture, Purdue University
There are certain characteristics that
suggest the water stress tolerance of plants. Small leaves, leaf
waxes, and minimal leaf area all lead to reduced water loss, and
therefore, drought tolerance. However, it is always best to refer
to reliable sources for lists of drought tolerant plants, such
as the one created for this article.
Large leaf areas can be detrimental
to growth and survival under conditions of water stress because
there is more surface area from which water can be lost. Therefore,
drought-tolerant plants will often have small leaves or, in the
case of conifers, needles that have low surface area. While this
is generally true, there are many plants with large leaf areas
that are drought-tolerant, such as southern magnolia (Magnolia grandiflora),
and sycamore (Platanus sp.).
Another way trees reduce leaf area is by having
deeper sinuses. Sinuses are the indentations between lobes on a
leaf. Trees that are more tolerant of dry conditions often have
deep sinuses, which decrease their total leaf area.
Drought-tolerant plants often accumulate waxes on their leaves
or needles. Waxes are thought to prevent water loss and reflect
light, which keeps leaf temperature from becoming too high.
Leaf hairs (called trichomes) appear as grey or
white pubescence and reflect light and reduce water loss. While
we still don’t
fully understand how trichomes affect plant water loss, leaves
that are covered with these small hairs typically lose less water
than those that do not.
Click image to enlarge
Holly waxy leaves