Ramble Report October 21 2021

Leader for today's Ramble: Linda
Link to Don's Facebook album for this Ramble
Number of Ramblers today: 27
Today's emphasis:  Trees and other vegetation on the flood plain
Reading:  Bob Ambrose read his poem, To Bring You Beauty.

I would bring you beauty
if I only knew how.
I would slip into spirit,

dissolve into autumn breeze
which carries the scent
of crimson sage

to clouds of yellow butterflies
in the afternoon light
of their lives.

As the press of obligation fades,
the busy pings, the urgent beeps,
and rumble of distant machines -

I hover with a bumblebee
in the spell of a purple aster.
I drift in scented air

on a lilting riff of mockingbird-song,
the swerve of a skipper,
a toddler's giggle

through the elusive realm
where beauty infuses all being.
I would bring you a portion

but, reaching, it slips
through re-embodied hands
and recedes like time itself,

its lingering afterglow
reflected in clouds
of evening gnats.

 

Show and Tell:

Overcup Oak Acorns

Linda brought a short terminal branch from an Overcup Oak with leaves and several acorns. She fooled us all when she asked what oak group the Overcup belongs to, White or Red? Those brave enough to guess called out Red, but Linda corrected us by showing that the pointed lobes didn't have bristle tips.

Ravenel's Stinkhorn

Kathy Stege brought a stink horn fungus, pale in color and the upper third covered in dark slime that contains the fungal spores. (The technical term for the slime is "gleba.") Stinkhorns attract flies with their odor. The flies eat the gleba, ingesting the fungal spores as well, and then fly off to other places. The spores pass through the fly's digestive system unharmed.
For more information (and photos) check out this photo essay by a regular reader of this blog:
Stinkhorns: Fungi No One Can Love? by Dr. Robert Wyatt

Announcements/Interesting Things to Note:

        Emily reported that the minimum number of Nature Rambler t-shirts had been ordered, so if you were holding back, you can still place your order before the first of November. Two shades of blue, Navy and Sapphire, and several styles. You can either pickup your order or have it mailed to you for a small additional charge. Remember, the more you order the more the Garden will get to support the new Butterfly Trail.

Today's Route:   We left the Pergola using the walkway beside the Children's Garden comfort station heading over to the mulched path just below the Forest Play area.  This joins the White Trail Spur which we followed to the Orange Trail Spur, which we followed to the Middle Oconee River floodplain.  At the river, we turned left on the Orange Trail, going downriver to the beaver marsh boardwalk.  We returned back to the Purple Trail, taking it back to the Visitor Center.

OBSERVATIONS:

 

Ramblers paused on the Orange Trail above the river, to discuss the characteristic landforms of a many southeastern floodplains. Standing on the toe slope above the floodplain we could easily view the flooded slough, the river levee, and the river itself. Many Piedmont rivers are lined with low, sandy berms called levees. These form when the river repeatedly overflows its banks and soil carried in the floodwater is deposited on the floodplain. The heaviest and largest soil particles - sand - fall out first, forming sandy levees along the river's bank. As the floodwaters continue to move across the land, finer soil particles - clay and silt - settle out, forming deep layers of fine-textured soil. Semi-permanently flooded areas called sloughs or back swamps form in the lowest areas of the floodplain. These are a distinctive feature here at the Garden. Gary told us about an old Native American term for a slough - a "yazoo" - for which the river and town (Yazoo City, Mississippi) are named (and also a national wildlife refuge in the Mississippi Delta).

Anyone interested in learning more about the ecology of southeastern river ecology, can read a great report written by Georgia's own Charlie Wharton in 1982: http://npshistory.com/publications/usfws/biological-reports/81-37.pdf

Dr. Wharton also wrote a report on the natural communities of the Botanical Garden available here.

View of floodplain from Orange Spur Trail

Several species of flood-tolerant trees occur in abundance in the Middle Oconee River floodplain, including Tulip Tree, Sweet Gum, Red Maple, Green Ash, Box-elder, River Birch, and American Sycamore.  Most of these trees can also thrive in uplands but may be outcompeted by upland hardwoods such as oaks and hickories.

Trees in flooded habitats often have buttresses and swollen bases which increase stability and may help to aerate the root system. The top of the swollen area corresponds to the depth of the flooding.

Red Maple with burls all over its trunk. When cut, these burls make the much-prized bird's-eye maple lumber.

Silverbell

Hop Hornbeam

Two understory trees that are often found on toe slopes above floodplains are Silverbell, with its distinctive striped bark, and Hop Hornbeam with rows of holes drilled by Yellow-belled Sapsuckers.

 

Large, female Joro spider on her web.
Very small male directly above her.

Entering the floodplain, we encountered a large Joro spider female on her web. Directly above her was a very small male. This disparity in size between male and female spiders is especially common among the orb-weavers. In non-orbweavers the two sexes are more nearly the same size.  So why should sexual size disparity have evolved in the orb-weavers? There have been many hypotheses suggested, but, to date, none have been convincing enough to have answered the question. A good recent review, written for a general audience, is available here.

 

Green Ash leaf

Green Ash is abundant in the wetter part of the floodplain. Its leaves are opposite and composed of 5 - 9 leaflets and its twigs are a dull, gray-green.

While walking the trail on the toe slope, we happened upon two graduate students from the Warnell School of Forestry who were surveying Green Ash trees for an exotic and invasive beetle known as the Emerald Ash Borer. One of the students, Mitchell Green, explained that their goal is to help develop a plan to battle this insect which began devastating ash trees in Michigan in 2002 and has recently been found in Georgia. Currently, they plan to import a species of parasitoid wasp as a form of biocontrol. Woodpeckers also like the larval form of EAB and can be a source of natural control. For more info, see: https://www.aphis.usda.gov/publications/plant_health/faq_eab_biocontrol.pdf.

Emerald Ash Borers kill trees by laying their eggs in the bark; when the larvae emerge they bore into the ash trees and feed on the living tissues under the bark, disrupting the movement of water and nutrients throughout the tree. An infested tree dies within 2-4 years.

Emerald Ash Borer beetle

 

Tunnels made by EAB larvae feeding just under the bark.

Box-elders are abundant in the floodplain and can be easily identified year-round by the clusters of branches that emerge from the lower part of the trunk. These branches arise from dormant buds under the bark that are stimulated to sprout by some kind of stress, such as branch breakage. Young branches and twigs are bright green all year. During the summer, look for opposite, compound leaves, usually with 3 or 5 toothed leaflets. The three-leaflet leaves look a lot like Poison Ivy leaves. And just to complicate matters, sometimes Poison Ivy grows up a Box-elder tree! Look for Poison Ivy's hairy stem to tell them apart.  

Poison Ivy growing at the base of Box Elder.

Clusters of paired samaras on Box Elder
Note: the "wing" is not bilaterally symmetrical.

A single samara of Green Ash;
the "wing" is more symmetrical than that of Box Elder.

Box-elder fruits are paired and winged, betraying the fact that it is actually a species of maple. Compared with the winged but much narrower fruit of Green Ash, which does not occur in pairs.

Red Mulberry leaves

Red Mulberry trees, another understory tree typical of bottomlands, are found in somewhat elevated parts of the floodplain where water does not stand for long stretches. Most Red Mulberry leaves are more or less heart-shaped and sandpapery to the touch. Some leaves may have a mitten-shape with one or two deep sinuses. In that case, it's possible the tree is a hybrid with White Mulberry (Morus alba), a native of east Asia. White Mulberry, the tree that supports the silk moth, was brought to Georgia in 1733 by Oglethorpe as an effort to develop a non-cotton, slave-free agricultural alternative for the new colony. Sadly, Oglethorpe's dream of a slave-free colony collapsed in less than a decade under pressure from farmers who saw their neighbors in South Carolina reaping the profits to be made in cotton cultivation by enslaved Africans. White Mulberry leaves are generally smooth and hairless, or only slightly rough to the touch, and usually have multiple lobes and sinuses.

A fallen River Birch

Fallen River Birch trunks are seen all along the levee and the adjacent Orange Trail. Typically found on levees, these trees have toppled as the riverbank erodes. The curling, papery bark is a distinctive indicator of this floodplain species.

Frosted Aster??

Small White Aster??

There are at least two species of fall-flowering white asters along the Orange Trail. They and two other common white asters are very hard to tell apart. Our best guess is that these are Small White Aster and possibly Frosted Aster. Kathy reported that these species make great garden plantings, becoming quite large and bushy under cultivation. And the flowers last a long time!

Cut-leaf Coneflower is still flowering though clearly on its way out.

Winged Elm is a bottomland tree and also an upland tree, quite happily thriving along interstate highways and upland ridges as well as in wetlands. The small, rounded oblong plates that make up its bark make some people think of tongue compressors.

Winged Elm leaves

Winged Elm bark

 

Pokeweed is still flowering and setting fruit even as older fruits are withering on nearby plants.

Climbing Hempweed

 Climbing Hempweed uses pokeweed and other vegetation as a natural trellis. Although a member of the composite family, this species lacks ray flowers, but its showy curved styles branches and mildly sweet scent call in the pollinators.

 

Sensitive Fern

Sensitive Fern has not yet succumbed to cooler night-time temperatures but will be one of the first to wither in the cold when it comes.

Tearthumb flowers

Tearthumb stem

Tearthumb flowers attest to their membership in the smartweed genus Persicaria, but nothing else in this genus (or in this habitat) has the sawtoothed stems that really will tear your thumb, not to mention hands and arms.

A super-large clump of Common Blue Violet dwarfs a smart phone.
Take that, Big Tech!

Leaves of an American Sycamore tree growing near the riverbank.

Downy Lobelia

The sinewy trunk of a Musclewood tree,
another member of the understory along riverbanks.

The old beaver marsh is lovely in the low light of autumn.

Rice Cutgrass dominates the grassy marsh. . .

. . .it too will leave your fingers in shreds if you rub your hand along the stiff hairs on its stem.

Japanese Beauty-berry

Japanese Beauty-berry, with its small leaves and berries, is planted elsewhere in the Garden and has escaped and become established at the edge of the marsh.

Duck Potato is common throughout the marsh.

A single plant of Buckthorn Bumelia, growing at the base of the Purple Trail.

As the trail turned upslope, typical upland species,
such as Chalk Maple, began to appear.

Rusty Blackhaw

Rusty Blackhaw; Lower leaf surface midvein.

 

Rusty Blackhaw, another upland species, growing along the Purple Trail. Its name comes from the clumps of rust-colored hairs along the midvein on the lower surface of the leaves.

The V-shaped formation of migrating geese flying above the river is a harbinger of cooler weather.

SIGN OF THE TIMES.

Help!! I'm falling!

 

SUMMARY OF OBSERVED SPECIES:

Overcup Oak                        Quercus lyrata   

"Ravenel's Stinkhorn"           Phallus ravenellii

Eastern Leaf-footed Bug      Leptoglossus phyllopus
American Beautyberry         Callicarpa americana
Tulip Tree                             Liriodendron tulipifera
Sweetgum Tree                    Liquidambar styraciflua
American Sycamore             Platanus occidentalis 

 Red Maple                           Acer rubrum
Winged Elm                          Ulmus alata
Mountain Silverbell               Halesia tetraptera
Hop hornbeam                      Ostrya virginiana
Joro Spider                           Trichonephila clavata
Box Elder                              Acer negundo
Poison Ivy                             Toxicodendron radicans
Red Mulberry                         Morus rubra
River Birch                             Betula nigra 

Small White Aster                  Symphyotrichum racemosum
Frosted Aster                         Symphyotrichum pilosum
Dotted Smartweed                 Persicaria punctata
Green Ash                              Fraxinus pennsylvanica
Trumpet Vine                          Campsis radicans
Cut-leaf Coneflower                Rudbeckia laciniata
American Pokeweed               Phytolacca americana
Sensitive Fern                         Onoclea sensibilis
Climbing Hempweed               Mikania scandens
Tearthumb                               Persicaria sagittata 

Common Blue Violet               Viola sororia
Downy Lobelia                         Lobelia puberula
Chalk Maple                             Acer leucoderme
Duck Potato                             Sagittaria latifolia
Rice Cutgrass                          Leersia oryzoides
Beautyberry                             Callicarpa sp.
Buckthorn Bumelia                  Sideroxylon lycioides

Rusty Blackhaw                       Viburnum rufidulum