These species, all found at the Arboretum, turn a brilliant red color in autumn due to a chemical called anthocyanin.
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Red swamp maple, Acer rubrum Devil’s walking stick, Aralia spinosa Blueberry, Vaccinium corymbosum Flowering dogwood, Cornus florida Hearts-a-bursting, Euonymus americana Virginia sweetspire, Itea virginica Sweet gum, Liquidambar styraciflua Tupelo, Nyssa sylvatica Sumac spp., Rhus spp. Sassafras, Sassafras albidum Possumhaw viburnum, Viburnum nudum
sweetgum (Liquidambar styraciflua)
along the paths. These youths’ leaves will only finally be pushed out when the new leaves come in the spring. This may help to protect the branch tips at the lower level from browsing deer through the winter and earliest months of spring. Some leaves have both the red and yellow pigment, producing a variety of multicolor variation like that found in sweet gum, sassafras, and sugar maples. After the red and yellow disappear, the brown or tannin is left, due to the final breakdown of the chemicals in the leaves. Like young beeches, some of the white oaks hold on to their brown leaves through much of the winter. The fallen leaves eventually break down and become part of the forest floor, holding moisture for the roots and improving soil structure. As rainwater travels through the decomposing leaves, some of the tannins are dissolved. Since tannin is a chelate, meaning that it clings to minerals such as iron, magnesium, and calcium, it helps redistribute these valuable minerals, enhancing the rich floodplain that nourishes many of our ephemerals, ferns, and mosses. This golden tea color from the tannin is visible in the waters of Blockston Branch all winter long as it travels leisurely downstream, a strangely quiet reminder of the riotous color display from whence it came.
Xanthophyll is the name of the natural compound responsible for the strong yellows in autumn leaves, and can be seen at the Arboretum in these species. Pawpaw, Asimina triloba River birch, Betula nigra Ironwood, Carpinus caroliniana Hickories, Carya spp. Redbud, Cercis canadensis Summersweet, Clethra alnifolia American beech, Fagus grandifolia Green ash, Fraxinus pensylvanica Spice bush, Lindera benzoin Tulip tree, Liriodendron tulipifera
For more information, see Fall Color and Woodland Harvests by D.R. Bell and A.H. Lindsey, 1990, Laurel Hill Press.
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