Hi, I'm Daphne Richards. Our question this
week is on photosynthesis and how plants respond
to shade versus sun, a topic that I am, being
a horticultural geek, very excited to discuss.
As I'm sure you know, plants perform photosynthesis
via chlorophyll, and I'm sure you also know
that chlorophyll is green, giving leaves their
characteristic green color. But have you ever
noticed that plants that are happier in shade
are usually darker green than plants that
thrive in sun? That's because the more chlorophyll
a plant has in its leaves, the darker green
it will be. Shade plants, often native to
tropical regions where they grow as understory
plants, need quite a bit more chlorophyll
to produce a sufficient amount of sugars to
feed themselves and grow, while plants that
grow in full sun don't need much chlorophyll
at all by comparison since sun is plentiful,
so they tend to be lighter green overall.
While this isn't a hard and fast rule, it
is pretty common. For example, compare a corn
plant with its yellow-green leaves to a hosta
or a cast iron plant. The difference in green
is striking. Shade plants also don't flower
as much as plants that prefer full sun, or
their flowers are less significant because
sufficient sunlight is necessary to produce
showy flowers. A sun plant, when placed in
a shady spot, will often not flower and may
be lanky and unattractive since it will try
to stretch up in search of sunlight. Variegation
is also common in shade plants. Those wide-striped
areas on variegated leaves lack chlorophyll,
and colors other than green are also more
common in shade plants, indicating a different
strategy altogether where the plant may have
replaced much of the chlorophyll with carotenoids
and anthocyanins, giving them orange or purple characteristics. Our plant this week is Sabal mexicana,
known commonly as Texas palmetto among many other common names. These Texas palm trees are native
to the Rio Grande Valley in extreme Southern
Texas near the Gulf of Mexico. They're normally
available in quite small containers, but don't
let their size in the nursery fool you. These
stout-trunked palms get up to 50 feet tall
in their native habitat. The larger they are
when purchased, the more expensive they'll
be since growth is very slow. The larger the
specimen, the older it is and the more time
and effort the grower has invested in it.
Because of this, most palms are sold according
to cala per inch rather than container size.
Although palms aren't generally planted for
their flowers, once mature, Texas palmetto
does produce creamy white flowers in spring
on stalks that may jut seven to eight feet
above the top of the plant. This is noteworthy since
birds are attracted to them and to the black
berry-like fruit produced afterward. As with
other palms, Texas palmettos are evergreen
and very adaptable to different soil types.
They're fairly xeric, but since these palms
are native to a warm, humid, relatively rainy
region, they do need a bit of water to stay
healthy. Listed as hearty only to Zone 8,
an unseasonably harsh winter may lead to the
demise of this tree, so be sure to plant on
the southwest side of your home, which is
warmest, and be prepared to protect this tree
during an especially harsh cold snap. Our
viewer pic this week comes via Facebook from
Diana Saunders. She captured this video with
her iPhone of a Zebra Longwing butterfly laying
eggs on a passion vine in September. Thanks,
Diana! We'd love to hear from you, so head
on over to klru.org/ctg to send us your questions,
photos, or video from your garden.
