Tuesday, December 9, 2008

Fall in Pinellas County

By Pam Brown, Urban Horticulture Extension Agent

We have had some cold weather early this year which has created some wonderful red, orange and gold colors in our trees and other landscape plants. Deciduous plants – those that loose their leaves in the fall – seem to magically turn colors with shorter days and colder temperatures. But, it seems that the combination of these two factors do not combine together in Pinellas County very often to produce these vibrant colors.

When a deciduous plant begins preparations for dormancy, the green colored chlorophyll begins to break down. But chlorophyll is not the only pigment inside leaves. There are other colored pigments that are masked by the intense green chlorophyll. These other pigments include carotenoids and anthocyanins. Carotenoids create the bright yellows and oranges and anthocyanins impart a red color.

It was believed that these colors simply appeared after chlorophyll breaks down, and that they served no function. However, research shows that in many plants, anthocyanins are not simply unmasked, but produced by leaves during the fall (Lee et al., 2003). There is very good evidence that the anthocyanins work like a sunscreen so that the plants can continue to take nutrients from the leaves as they fade (Yamasaki, 1997; Chalker-Scott, 1999; Matile, 2000).

All of this science aside, it is very nice to enjoy some lovely fall colors in our area for a change.

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