Fall begins today with the autumnal equinox. As the photos below illustrate, the arboretum remains green―seasonal
fall color and cool temperatures arrive late to northwest Louisiana. A close inspection of our tree of the week hints at seasonal change. This week we are examining the green leaves of a young, volunteer sweetgum (
Liquidambar styraciflua).
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| The volunteer sweetgum germinated in the middle of a groundsel bush (Baccharis halimifolia), on a grassy, gradual slope near Cline Hall. In this photo, the groundsel conceals the sweetgum. Note the groundsel bush's gnarly, sprawling branches. |
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| Another view reveals the slender, white trunk of the sweetgum, but its green leaves blend in with the surrounding vegetation. |
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| Our volunteer was added to the catalogue in summer 2017. At that time, the tree was at minimum three years old. An exact age is unavailable. |
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| Standing in its shade, we can appreciate the characteristic 'winged', or 'corky', bark of the young sweetgum. |
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| Can you see the ridge along the branch? |
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| The 'wings' can be flat, straight, wavy, and non-contiguous. |
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| You might simply find bumps or notches along a branch rather than a ridge. |
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| Although our young sweetgum is still green, on the first day of fall, the star-shaped leaves show signs of color change. But what is causing the yellow splotches? Is it simply seasonal color change, or could it possibly be a sign of deficient growing conditions resulting in chlorosis? We shall keep an eye on this individual and hope for dazzling autumnal colors. |
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| Leaf blade and leafstalk each measure approximately 3¼ inches in length. |
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| Leaf size varies. Here we have a bigger leaf with the same yellowish-green splotches. |
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| Underneath, sweetgum leaves are pale green. |
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| Sweetgum leaves have palmate venation. |
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| Zooming in on the base of the leaf blade, we see brown fuzzy patches in between the veins. |
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| Leaf margins are serrate. |
