Photo by Joani MacCubbin
Our calendars have told us that Fall has arrived here in Florida even though the temperatures have only fallen just a little bit and the humidity has subsided slightly. But it is still ‘technically’ Fall here and some of our tree leaves will begin falling soon. Crape myrtles have already started losing their leaves but if they are planted near a street light they could be delayed. Winged and drake elms, sycamores, river birches, sweet gum, chaste tree, dogwood, redbud have already begun their transition into fall.
Scientists have studied these fall changes for years and still don’t know all the details but enough to shed some light on why it happens. Three things influence leaf change.....leaf pigments, length of night and weather is involved but only slightly. As you know fall nights become longer and the amount of daylight for the trees is much less.
As with any artist a palette needs paint and Mother Nature’s palette needs pigments also. She uses 3......which are chlorophyll that gives the leaves shades of green......Carotenoids which produce yellows, oranges and brown.....and anthocyanins which add the reds and purple to her palette.
Both Chlorophyll and Carotenoids are in the leaf cells throughout the growing season while the anthocyanins are produced in the autumn in response to bright light and excess plant sugars in leaf cells. When fall comes and the length of our nights increase chlorophyll production slows down....then stops and all the chlorophyll is destroyed. The carotenoids and anthocyanins that are left are then unmasked allowing them to show off their ‘fall’ colors that were always there, but hidden, all through their growing season..
Temperatures and moisture do have a hand in color change and can affect chlorophyll production and can alter the colors to make them more or less intense.
I think Mother Nature let all those leaves fall for us to use in our gardens to help us prepare our planting areas......it’s a free gift from her. And using them will make it harder for them to root down and much easier to pull up. So rake them up and use them wisely.....instead of sending them to the curb for the trash guys to pick up.