Leader for today's Ramble: Linda
Authors of today’s Ramble report: Linda and Don. Comments, edits, and suggestions for the report can be sent to Linda at Lchafin (at) uga.edu.
Insect identification: Dale and Don
Link to Don’s Facebook album for this Ramble. All the photos that appear in this report, unless otherwise credited, were taken by Don Hunter. Photos may be enlarged by clicking them with a mouse or tapping on your screen.
Today's emphasis: Changing leaf colors and other natural
events in the fall
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| Ramblers headed downhill on the White Trail extension |
Reading 1: Cathy read a poem by M.K. Creel.
Letting Go: Poem for a Monarch butterfly
She should be soaring
on a northwest wind,
instead of lying here,
on a makeshift blanket
of milkweed & pink asters;
her crumpled wet wings
glowing like red embers
in the day’s dying light.
I don’t know whether to end
her suffering, or simply give
a quiet place to slip back
into slumber, safe from
squawking jays and stalking cats,
the peppering swarm of
little black ants in the leaves
where I found her
beneath a split chrysalis.
When it’s my time to let go,
give me this sun-gold spot
on the back porch,
a trilling cricket chorus
& spider silk sparking
in a cathedral of branches,
that scent of jasmine, drifting.
Reading 2: Linda read this passage from Donald Culross Peattie’s An Almanac for Moderns: “October 26: It is nearly impossible to be sad, or even listless, on a blue and gold October day, when the leaves rain down – rain down, not on a harsh wind, but quietly on the tingling air. They fall and fall, though not a breeze lifts the drooping flags of their foliage. You stand a moment before a late, last Ash, watching. It seems as though the tree were actively engaged in shedding its attire, snipping it off, cutting it adrift. Pick up a leaf fallen at your feet, and examine the base of the leaf stalk. It feels hard to the touch; it is hollowed out. Had you a microscope, and cut section of the leaf, you would see that indeed it had been cut off. The growth of a ring of callus cells, in a perfect ball and socket articulation, had predestined the fall. Wind need not tear the foliage down, nor decay set in. The tree itself passes invisible shears through its own auburn crown.”
Announcements and other interesting things to note:
The annual bird seed sale fundraiser is ongoing at Sandy Creek Nature Center. Order your bird seed here.
The
Johnstone Lecture, sponsored by the Friends of the State Botanical Garden of
Georgia, will be held this year on Tuesday, October 24, 6:30-8:30 pm in the
Garden’s Visitor Center. The speaker is Abra Lee, author of the
forthcoming book Conquer The Soil: Black America and the Untold Stories of Our
Country’s Gardeners, Farmers, and Growers. Ms. Lee will speak about “The
Invincible Garden Ladies” – legendary figures in horticulture who forged a path to
economic and social freedom, providing inspiration for plant lovers today. The
lecture is free but you must register here.
The
Garden’s Full Moon Hike for this month’s Hunter Moon is October 28, 8:00- 9:30
pm. $5 per person. For more information and to register, click here.
Here's an inspiring article on the value of small urban forests.
Today’s Route: We followed the paved path through the Lower Shade Garden, took an unintended detour through Dunson, and made our way to the White Trail extension that passes by the Forest Play Area. We headed downhill and walked the trail along the lower slope above the floodplain. After a while, we were turned back by a freshly fallen tree so re-traced our steps except veering off onto the trail to the power line right-of-way. We took the ADA path through the floodplain almost to the Middle Oconee River before heading back to the cars.
OBSERVATIONS:
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| Bottlebrush Buckeye leaves turn yellow in the fall. |
Bottlebrush Buckeye is not native to the Georgia Piedmont; it occurs naturally only in southwest Georgia along the Alabama border, and then spreads north and west throughout Alabama. It leafs out in late spring and flowers in June. The leaves of our Piedmont native, the Painted Buckeye, are the first to emerge in our forests in the spring and the first to turn brown and drop, often as early as August. The two species’ ranges do not overlap in Georgia.
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| Making our way down the White Trail extension, we spotted a small patch of newly emerged Cranefly Orchid leaves. The upper leaf surface is a dark, bronzy green, the lower surface deep purple. These leaves will persist through the winter, taking advantage of the sun that passes through the leafless canopy to produce and store carbohydrates. Next spring these leaves will wither and disappear and, a few weeks later, a single leafless flowering stalk will emerge from a corm (a bulb-like underground storage organ). Here’s a good article about this species, the most common orchid in Georgia. |
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| We stopped to look at numerous downed and damaged trees along the trail. This damage – trees uprooted and crowns torn from trunks – most likely occurred on July 20th, when a severe storm wreaked havoc on much of the Athens area, killing many trees, causing heavy property damage, and shutting off electricity to parts of town for several days. |
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| This down and dead limb is populated by two wood-decomposing fungi, a pale orange Stereum species (no common name) and a black one known as either cramp balls or carbon balls. |
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| Walking along the lower slope above the floodplain, we encountered many Yellow Crownbeard plants, some of them providing lunch for black and green aphids (species unknown). |
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| A Tuberculated Crab Spider in the
midst of the aphids, legs raised, in predator mode. Don suggests that this fierce pose was actually directed at him, manipulating the stem in pursuit of a good photo angle, rather than the aphids. |
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Thick patch of webbing on the
underside of a Yellow Crownbeard leaf Dale told us it was created
by a spider for one of two purposes: as a molting platform where the spider
stands as she unzips her too-tight exoskeleton and emerges wearing a fresh,
larger one; or, it could be a silken cover, hiding a clutch of a spider’s eggs. |
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|
A
patch of Witch Grass in fall-flowering mode |
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| Chalk Maple leaves usually turn red in
the fall but are mostly paler this year. |
When nights lengthen in the fall and temperatures drop, hormonal changes in a plant trigger several events. Chlorophyll, the green pigment, begins to break down and the components of chlorophyll are resorbed into the body of the tree, a process called nutrient retrieval. These components – primarily nitrogen and phosphorus – are vital plant nutrients. As the chlorophyll breaks down, yellow and brown pigments that have been present in the leaf all spring and summer are exposed. Carotenoid pigments are responsible for yellow and golden colors in Tulip Trees, some hickories, and others. Tannin, a metabolic waste product stored in the leaves of trees, produces shades of brown in many oaks, some hickories, Hop Hornbeam, and others.
What about the brilliant red, orange, and maroon leaves of trees such as maples, Sourwood, Black Gum, Sweet Gum, Scarlet Oak, and White Oak, and shrubs such as Sumac? The same hormonal changes mentioned above cause the chlorophyll to break down and nutrient retrieval to proceed, and also triggers the production of a different pigment, anthocyanin (pronounced an-tho-sigh-uh-nin), which is dissolved in the sap in the leaf. This is the same pigment that we see in new growth in the spring where it acts as a sun screen to protect tender new growth (see this ramble report from March 2022). The different shades of red/orange/maroon in autumn leaves depend on the pH of the sap. The function of anthocyanin in autumn leaves has not been fully explained, but the best current theory is that it is, once again, acting as a sun screen and protecting leaves from sun damage, thereby prolonging their time on the tree and lengthening the period of nutrient retrieval from the leaves.
Well, this is interesting science, but what we really want to know is, when and where is the best time to see fall leaf color? Yellow and brown colors will always appear as the chlorophyll breaks down, but the brilliant reds and oranges are more weather-dependent. Warm, sunny days and cool (not freezing) nights promote the formation of anthocyanin, creating the most spectacular color displays. In our area, this combination of conditions occurs earlier and more reliably in the mountains of north Georgia and North Carolina in mid-October (Black Gum and Sourwood color gets underway much earlier). And the leaves in Athens are often gorgeous in late October and early November.
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| Black Gum leaves The weeks of drought and high temperatures we’ve experienced since the first of September may have robbed trees like Black Gum of the opportunity to accumulate anthocyanin in their leaves, thus dulling their color. Total rainfall in Athens in September was 0.18 inches – the average for September is 3.89. Higher temperatures also affect leaf color; here is an analysis of the impact of climate change on fall leaf color. |
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Ebony Spleenwort is one of
two native ferns
that overwinter in Georgia’s Piedmont forests, the other being Christmas
Fern, below. You can easily tell them apart because Ebony Spleenwort's
leaflets are usually less than one inch long and are more or less oblong in shape; Christmas Fern leaflets are
usually more than one inch long and are shaped like Christmas stockings.  |
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| Each fall Don looks for an opportunity to capture a "floating" leaf, then skillfully edits out the telltale line of spider silk. In this case, the leaf had no visible means of support at all. |
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| Gilled Polypore fungi on a fallen limb along the trail |
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Given his talents with photography, fungi, and insects, it's easy to forget that Don trained and worked as a geologist for decades. Then he comes along and reminds us by supplying this description: "This is a chunk of weathered amphibole gneiss, found on the slope above the floodplain. It has clear-ish quartz crystals, white to pink grains of feldspar, and black amphibole crystals. The presence of iron in the rock is obvious based on the red staining on the weathered surfaces. This naturally occurring rock, high in calcium and magnesium, is responsible for the presence of calcium-loving plants such as Chalk Maple and Carolina Milkvine in the Garden." |
Just before we reached the
floodplain, we encountered a downed tree across the trail that was nearly
impossible to get around, so we turned back and headed for the right-of-way. The vividly flowering floodplain plants of August are now muted in color but loaded with fruits and seeds. I was reminded again of how rich in plant species this sunny wet area is.
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| Camphorweed seed heads |
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| Small White Morning Glory fruits |
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| Wingstem seed head The orange structures are wings attached to each black fruit. |
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| The seed heads of Tall Ironweed resemble tiny shaving brushes. |
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| Maryland Senna fruits are legumes. Photo by Dan Tenaglia |
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| Buttonbush fruits are held on round heads that persist for several months, providing winter food for birds. |
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Nimblewill, a grass in the same
genus as Pink Muhly Grass, is a sprawling wetland species with reddish fruits crowded onto long, slender spikes (below). |
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| Some plants in the floodplain are still flowering, including this Tall Ironweed with bright pink flower heads and Dodder (below). |
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Dodder is a parasitic plant; it has no leaves and its twining stems are orange, completely lacking in chlorophyll. Once mature, it has no roots or other connection to the soil. As the orange stems wrap around the host plant, they sink tiny sucker-like pegs called haustoria into the host and extract carbohydrates, minerals, and water. In Don's photo above you can see the host plant, a flowering Tall Goldenrod, and the orange stems, white flowers, and off-white fruits of the Dodder. |
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An unusual Bowl and
Doily spider web  |
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| A recently eclosed Gulf Fritillary drying out or warming up on a blackberry branch. |
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| Lined Orbweaver in its delicate orb |
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| Four-humped Stink Bug Don wrote about this find: "In a first known Nature Ramble sighting, a Four-humped Stink Bug was spotted on a Maryland Senna bean pod. Although there are several sightings in the Athens area, there have been no Four-Humped Stink Bugs reported to iNaturalist from the Botanical Garden. It’s quite a striking critter!" |
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| A female Green Lynx Spider is guarding her large egg case, partially hidden inside the curl of a flowering branch of Tall Goldenrod. |
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| Red Goldenrod Aphids (the red aphids are females, the green aphids are males) |
SUMMARY OF OBSERVED SPECIES:
Bottlebrush Buckeye Aesculus parviflora
Cranefly Orchid Tipularia discolor
White Oak Quercus alba
Stereum fungi Stereum sp.
Carbon Ball fungi Daldinia concentrica
Yellow Crownbeard Verbesina occidentalis
Tuberculated Crab Spider Tmarus angulatus
Aphids, not specified Family Aphidoidea
Witch Grass Dichanthelium sp.
Monkey Grass/Creeping Liriope Liriope sp.
Black Gum Nyssa sylvatica
Chalk Maple Acer leucoderme
Ebony Spleenwort Asplenium platyneuron
Ground Ivy Glechoma hederacea
Gilled Polypore fungi Trametes betulina synonym Lenzites betulina
American Beech Fagus grandifolia
Camphorweed Pluchea camphorata
Common Dodder Cuscuta sp.
Small White Morning Glory Ipomoea lacunosa
Nimblewill Grass Muhlenbergia schreberi
Arrowleaf Tearthumb Persicaria sagittata
Bowl and Doily Spider Frontinella pyramitela
Common Wingstem Verbesina alternifolia
Buttonbush Cephalanthus occidentalis
Gulf Fritillary Agraulis vanillae
Lined Orbweaver Mangora gibberosa
Maryland Senna Senna marilandica
Four-humped Stink Bug Brochymena quadripustulata
Green Lynx Spider Peucetia viridans
Red Goldenrod Aphid Uroleucon nigrotuberculatum
