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
Fungi
identification: 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.
Number of Ramblers today: 27
Today's emphasis: Changing leaf colors and other natural
events in the fall
 |
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:
 |
| 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.
 |
| 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. |
 |
| 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. |
 |
| 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. |
 |
| 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). |
 |
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.
|
 |
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. |
 |
|
A
patch of Witch Grass in fall-flowering mode
|
Witch
Grasses flower twice a year. In the spring, a rosette of leaves puts up
erect flower stalks, then hunkers down through the summer heat,
the flower and fruit stalk disappearing. In late summer or fall, that same plant sends out long,
sprawling branches bearing flowers and seed heads at their tips. This
two-season flowering habit is reflected in the genus name, Dichanthelium:
dich = two, anthelium = flower. Witch Grasses are among the hardest plants to identify in our region. Here is what the Flora of the Southeastern United States has to say about it: "Dichanthelium
is one of the most complex and confusing genera in our region. A taxon that is
distinct in one part of its range may be indistinguishable from another taxon
elsewhere... The genus requires careful collection and close observation of
several characters [before making a species identification]."
 |
Chalk Maple leaves usually turn red in
the fall but are mostly paler this year.
|
Here in our temperate deciduous
forests, leaves turn many colors in the fall, ranging from pale yellow, through
gold, orange, coral, red, purple, and brown – with many gradations in between.
There are four categories of pigment involved in leaf color change – chlorophylls, carotenoids,
tannins, and anthocyanins – and two different processes.
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. |
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.
|
 |
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.
|
 |
| 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. |
 |
Gilled Polypore fungi on a fallen limb along the trail
|
 |
|
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.
 |
Camphorweed seed heads
|
 |
Small White Morning Glory fruits
|
 |
Wingstem seed head
The orange structures are wings attached to each black fruit.
|
 |
The seed heads of Tall Ironweed resemble tiny shaving brushes.
|
