Autumn Colors

These pictures were taken in mid-November around the Atlanta Temple and represent some of the amazing color displays from all the plant diversity. The north drive/stair area is by far the best spot for autumn color and is one of my favorite parts of the property. Fothergilla gardenii 'Mt. Airy' is a little deciduous shrub in the Hamamelidaceae family (others in this family are Corylopsis--winterhazel, Hamamelis--witchhazel, Loropetalum, Parrotia--ironwood, and Liquidambar--sweetgum. Fothergilla leaf color is an amazing mix of red, orange, yellow, and most of these shrubs are planted in masses of five or seven, so it is a nice swath of color in the landscape.
The leaf change in autumn is mostly brought on by the changing length of the days (shorter days, longer nights), which send a message to the plants to slow and eventually stop their production of chlorophyll. The green pigment in leaves from chlorophyll is broken down and destroyed and in its place carotenoid pigments, which have been present all along in the chloroplasts of leaf cells, but have been masked by the cholorphyll, become more apparent. Carotenoids make the yellow, orange, and brown pigments in various plants. The other pigment type, anthocyanins, (blue, purple, red) are produced in response to autumn light changes and sugar excesses in the leaves.
Day length is the strongest factor for leaf color change, but temperature and moisture are also factors. For example, the best autumn color will follow a warm wet spring, non-droughty summer weather, and warm sunny autumn days with cool (non-freezing) nights. The warm days produce a lot of light, and in turn, a lot of sugar, which brings about the most brilliant anthocyanin production. The red/crimson display, therefore, is variable from year to year, while the carotenoid pigments, which are always present, are essentially the same from year to year.

Some of the red/crimson autumn leaf plants on the property include: Dogwood (Cornus florida), Sweetgum (Liquidambar styraciflua), Red maple (Acer rubrum), Burning bush (Euonymus alata), and Virginia sweetspire (Itea virginica 'Henry's Garnet'). Some of the yellow/orange/brown autumn leaf plants on the property include: Hickory (Carya spp.), Redbud (Cercis canadensis), Tulip poplar (Liriodendron tulipifera), Bottlebrush buckeye (Aesculus parvifolia), Sugar maple (Acer saccharum).