What's Blooming Week of March 19: Live Oak Tree

“Fall in Florida”
(February-May
in the lower Florida peninsula, especially along the coasts)

Live Oak : Quercus virginiana, Quercus geminata
Origin:  Southeastern United States

There are many ecosystems on our planet. Most of them go through some sort of cycle or another, and many of these cycles are seasonal in nature. In temperate areas, the main focus is on temperature; winter versus summer. In tropical areas the focus is moisture:  rainy season and a dry season. Here in the coastal areas of Florida, we live in a “semi-tropic” environment. This means that we’re not totally tropical, and it’s colder in the winter than the summer, but that the main ecological factor is moisture. So we have very rainy summers, filled with tropical storms and afternoon thundershowers. Then the rains start to peter out a bit through the autumn, until late winter, when someone totally shuts off the tap. In February and March, we have dry, windy days, which dessicate plants. It is this time of year that many of our native trees, from gumbo limbos to sea grapes to oaks, shed their leaves. It’s “Fall in Florida.”

Plants actively grow through our winters. It’s in the winter time that most Floridians grow vegetables, which seems crazy to someone in Vermont. So for our trees to drop their leaves in Autumn, just before the growing season, would be counterproductive. After all, it’s the leaves that feed the plant. Come February, however, the leaves are doing a disservice. They are hanging in the breeze, transpiring all the moisture out of the plant and into the dry air, while the rains have stopped and no new water is available. And if a tree is wind-pollinated, like an oak tree, then this dry and windy time of year is ideal for blooming. Quercus virginiana and Q. geminata are called “Live Oaks” because they push new growth before blooming and dropping last year’s leaves, which causes them to seem evergreen. Laurel Oaks, Quercus laurifolia, drop all of last year’s leaves first, then bloom and then push out next year’s leaves. Both are blooming right now, which is why so many suffering from pollen allergies are in misery, and why our cars are covered in a fine gold dust.

So whether it’s in response to drought conditions, or an evolutionary plan to enable cross-pollination between two trees miles apart, this dry and windy time in Florida is when you’ll see bags full of leaves out on the curb, not September. Think of leaves like skin cells. After enough time, damage from insects, the sun, or other factors in the environment can really start to affect the leaf’s ability to photosynthesize. Dropping them and flushing out anew is a necessity, but creates a brief period where the plant has lost the ability to manufacture food; this process must be undertaken at the right time. Up north in winter,  the trees are already dormant. In more tropical areas, plants take their dormancy in the dry season, which is in full swing here in Sarasota. All of the pathways at the south end of the gardens should be covered in sea grape leaves for the next month or two, and the oaks in our parking lots are dropping leaves daily.

 

Text by David Troxell