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.
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: Frost flowers and other fall phenomena.
Reading: Linda read from a piece written by our own Dale Hoyt in 2012 and first read at the October 13, 2016 ramble.
"Autumn has an abundance of dreary, drizzly days when everything is drained of color and the chill penetrates to the bone. On such days, it’s difficult not to be depressed and the gray sky just reinforces that absence of cheer. But fortunately there is one joy that overcast skies cannot diminish: the Ginkgo tree. As fall begins, the Ginkgo starts to absorb all the green from its fan-shaped leaves. They become yellow at their base and the border between green and yellow gradually advances to the edge of the fan, as if all the green is being inhaled into the tree itself. Then the tree seems to hold its breath, as if waiting for some sign. When that mysterious signal arrive, the tree suddenly exhales and all the lemon-colored leaves cascade to the ground within a few hours. If you’re lucky enough to be standing under a Ginkgo at that very moment you can experience the joy of their soft pelting – summer sunlight and air made palpable – as in their twisting descent they brush against your head and hands, casting your shadow on the earth beneath. Their brilliant yellow defies the drab autumnal sky and, for a moment, you can imagine you see the sun reflected in the pooled leaves beneath the naked branches above. (Thank you, Dale!)"
Announcements and other
interesting things:
The ramble leader next week will be one of our favorite guest leaders, Dan Williams, forester and geology expert.
Reminder: The Nature Rambler book group is re-grouping after a three-year, pandemic-related hiatus. We will meet on Thursday, November 30, 10-11:30am in the Adult Classroom in the Garden's Visitor Center to discuss dates and times of future meetings and to select a list of books for 2024. Bring a book (or a description of a book) that you'd like the group to read.
Interesting research conducted by a UGA student: "The Secret in the Spots on Monarch Butterflies’ Wings."
Gross, but engrossing, article: These Tiny, Beautiful Wasps Eat the Hearts Out
of Cockroaches.
Today's Route: We walked through the Lower Shade Garden and Dunson Garden and then out into the lower floodplain in the right-of-way, turning sharply left (south) and up on the slope where we saw hundreds of "frost flowers." As the sun rose higher and melted the ice, we walked downhill and turned east onto the Orange Trail, walked to the marsh boardwalk, then returned to the Visitor Center via the Purple and Flower Garden Trails.
“How frost flowers form: The water in the soil enters the root system by a process called osmosis. Osmosis is the term describing the movement of water across a cell membrane from a more dilute solution to a more concentrated solution. In this case the more concentrated solution is the sap in the root system and the less concentrated solution is the water in the soil. This movement of water into the root causes the sap in the plant's conductive tissues to rise. If the stem above has been injured or has a weakened skin the water will ooze out at the damaged spots. When the temperature is low enough this oozing water will freeze, beginning a frost flower. This 2013 article by James R. Carter in the American Scientist magazine is the best discussion I have found on how such lovely and delicate features form. In his article, Carter also mentions a Georgia connection to the phenomenon: ‘. . . physician and naturalist John LeConte of the University of Georgia made many insightful observations about whole and cut-off stems, both of which grew ice. He noted that many plant stems were dead and dry at the time of year when he did his study, although the roots might have been alive, but the ice formation therefore didn’t seem to be connected to the plant’s physiological functions. He observed, “At a distance they present an appearance resembling locks of cotton-wool, varying from four to five inches in diameter, placed around the roots of plants; and, when numerous, the effect is striking and beautiful.’"
If
you missed the ramble on Thursday and want to see this phenomenon, wait until
the overnight temperatures are below freezing and go to the Bot Garden early
(the grounds and natural areas are open at 8:00 a.m.), before the sun comes
over the trees. We were in the right-of-way by 9:30 (Daylight Saving Time) and the west-facing
slopes were still in shade. The vegetation was covered with lots of beautiful
icy features and hundreds of frost flowers hugged the dried stems of
Frostweed.
When we arrived at the right-of-way,
we were delighted to see an entire hillside dotted with frost flowers. Most of
us plunged into the head-high stalks of Wingstem and Crownbeard in search of
the most beautiful formations. Because this area was not mowed during the
summer, most of the frost flowers we saw were “swords” – long, icy formations extruded
from vertical splits in the White Crownbeard stems. Don photographed one sword,
with Gary for scale, that measured 4 feet, 2 inches long. Formations that are
more like flowers are found on plants that have been mown or chopped close to
the ground.
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| Frost ‘Sword’ more than 4 feet tall |
All the plants in the shaded areas of the right-of-way, from grasses to blackberries to Sweet Gum saplings, were touched by frost.
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| Frosty Late-flowering Boneset and Perilla Mint |
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| Ice crystals on Common Mullein leaf |
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| Mistflower with ice crystals |
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| Maryland Senna pods |
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| Sweet Gum leaves |
Don
shared this piece of Nature Rambles history: “We
first saw frost flowers on our November 20, 2014 Nature Ramble. We had dropped
down the White Trail to the Orange Trail Spur and headed out into the powerline
ROW. As soon as we exited the woods, we saw what looked like wads of paper and
white garbage bags littering the ground. We were all disgusted and dismayed. Only
when we got up close did we realize we were looking at hundreds of beautiful ice
formations ‘growing’ out of recently mowed White Crownbeard stems on the side
of the hill. Here are some photos of what we saw on that day.”
As the sun topped the tree line, we headed to the river and turned east along the Orange Trail to seek what we could find in the floodplain.
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| Samara-laden Box Elder illuminated
by the rising sun Box-elders are maples – their fruits are the familiar winged samaras (aka "helicopters") produced by all maples.  |
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Chalk Maple’s bright red leaves are a clue to its close relationship to Sugar Maple. |
%20and%20a%20Chalk%20Maple%20(lower%20right).jpg) |
| Red Maple leaves (upper) may be red or yellow or a mix of both and have teeth along their lobed margins. Chalk Maple leaves (lower) are lobed but the margins are smooth, completely lacking teeth. |
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| Distinctively striped bark on the
branches of Silverbell trees As branches grow and expand, fissures form in the bark, exposing orangish inner bark (below). A mature Silverbell has dark, platy bark with a purplish cast.  |
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| Roger inspecting the sinewy
trunks of two Musclewood trees |
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| “Cat-scratched” bark of Hop Hornbeam |
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|
Witches'
Brooms in the upper branches of Musclewood and Hop Hornbeam trees |
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| Spiral grain of a Hop Hornbeam
tree growing on the river levee There are several hypotheses
about what causes spiral grain in trees, but they all come down to different kinds of stress –
from wind, flooding, unstable soils, or lack of nutrients. In this
case, frequent flooding and unstable soils, coupled with downriver
winds, probably induced spiraling. Spiraled trunks are less likely to be
torn apart by such mechanical stressors. |
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| Fallen Basswood leaves, with their distinctive asymmetrical base, littered the ground beneath the trees. |
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Basswood trees typically have multiple trunks of different ages and sizes, almost always with a ring of young sprouts around the base. The bark consists of long, flat, parallel ridges separated by narrow, shallow furrows. |
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| Basswood flowers are held in clusters at the tip of a stalk that is attached to a bract (a bract is any leaf-like structure associated with flowers). In the case of Basswood, the bract is about 4 inches long and half an inch wide, shaped like a tongue depressor, with the flowering stalk arising about midway. This is hard to visualize so here’s a photo taken in the spring. |
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| Also known as Linden, Basswood
flowers have long been used to make a fragrant, medicinal tea. Photo by Evelyn Fitzgerald, Flickr |
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| A fallen Southern Red Oak leaf with its distinctive, curved midvein and bell-shaped base. The species name “falcata” derives from the Latin word “falc-“ meaning sickle, referring to the curved midvein. |
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The female Possumhaw Holly near the end of the Purple Trail has lost most of its berries to birds and squirrels. This berry is hanging from the tip of a “short shoot.” |
Short
shoots are familiar to anyone who has looked closely at a Ginkgo tree . They are shoots that sprout laterally from the long branches that
make up most of the tree’s crown and are usually found well inside the crown of
the tree or shrub. Short shoots grow only a few millimeters a year and always bear
a cluster of leaves – many more leaves than found on the tree’s long shoots.
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| Ginkgo short shoots in the spring |
The
existence of short shoots has mystified botanists: why would trees (or shrubs)
produce the majority of their leaves on shoots contained inside the tree’s
crown where they are heavily shaded? Isn’t the whole point of a leaf to capture
as much sunlight as possible? A recently published study has one possible answer: producing, maintaining,
and supporting branches and twigs costs a tree a lot of energy. Short shoots cost
the tree less energy than long shoots, more than offsetting the reduced amount
of captured light, and with lots of energy left over to produce more leaf area. Another feature of short shoots is that, in
many of the plant families that have them, flowers and fruits are produced almost
exclusively on short shoots, efficiently locating this energy expensive process
near the most leaves. This too reflects the fact that, with short shoots, energy
can be diverted from long shoot growth to the expensive process of flower and fruit
production. Some plant families whose species produce short shoots
include Ginkgo, Rose, Birch, and Holly. Interestingly, in some of these species a
short shoot may, after a few years, convert to a long shoot.
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| Drawn by the fragrance of the flowers on a large Sasanqua Camellia bush, Don was surprised to find, on this freezing cold morning, Eastern Yellow Jackets busily sipping nectar from the flowers. Yellow Jackets will survive a night or two of freezing temperatures but eventually succumb, with only the queen overwintering to re-start a colony next spring. |
SUMMARY OF OBSERVED SPECIES:
Frostweed, Virginia Wingstem Verbesina virginica
Common Mullein Verbascum thapsus
Sweet Gum Liquidambar styraciflua
Late-flowering Boneset Eupatorium serotinum
Perilla Mint Perilla frutescens
Common Wingstem Verbesina alternifolia
Georgia Basil Clinopodium georgianum
Blue Mistflower Conoclinium coelestinum
Maryland Senna Senna marilandica
Box Elder Acer negundo
Chalk Maple Acer leucoderme
Silverbell Halesia carolina
Musclewood Carpinus caroliniana
American Hophornbeam Ostrya virginiana
American Beech Fagus grandifolia
Basswood Tilia americana
Southern Red Oak Quercus falcata
Sourwood Oxydendron arboreum
Red Maple Acer rubrum
Possumhaw Ilex decidua
Sidewalk Firedot Lichen Xanthocarpia feracissima
Sasanqua Camellia Camellia sasanqua
Eastern Yellow Jacket Vespula maculifrons
