Ramble Report November 2 2017

Today's Ramble was led by Linda Chafin.

The photos in this post, except where noted, came from Don's Facebook album (here's the link).

Today's post was written by Linda Chafin with minor additions by Dale Hoyt.

26 Ramblers met today.

Today's readings:

Bill Pierson shows a soon-to-die grasshopper

Bill Pierson showed us another of his Chinese calligraphy paintings. The translation: “Grasshopper at the end of autumn – to its end.”

Bob Ambrose recited his poem, End Times, Again.

(This poem was composed and recited on a November Ramble last year. Click here for the text.)

 

Today's Route:   From the Arbor we took the right side path through the upper Shade Garden; at the bottom of the Shade Garden we went through the Dunson Garden and then walked along the access road toward the Mimsie Lanier Center, stopping at a large bed of Georgia Asters. We then returned to the Visitor Center for refreshments and conversation at Cafe Botanica.

Shade Garden:

Virginia Creeper vine with stout hold-fasts
(photo courtesy of Jeremy P. Stovall)

Virginia Creeper vine; note the expanded pads of the hold-fasts
(Photo courtesy of Jeremy P. Stovall)

Our first stop was a large Loblolly Pine with a long Virginia Creeper vine growing up the trunk and into the crown. Although its leaves had fallen, we were able to identify the vine as Virginia Creeper, and not one of the other woody vines with aerial rootlets (such as Poison Ivy), because Virginia Creeper has coarse aerial rootlets that are tipped with tiny adhesive disks that cling to bark. Poison Ivy’s aerial rootlets are very fine, dense, and dark brown and lack the disks.

We then moved on down the path, past a white blooming Sasanque Camellia, to an area where four or five large trees have been felled by summer storms and Hurricane Irma, which came through Athens as a tropical storm on September 11. The loss of a tall, large-crowned tree creates a hole in the canopy called a “light gap” where there once was a solid canopy over the area. In this case, the gap is large because of the large number of trees that blew down. Where once people thought of storm-downed trees as simply a loss, we now recognize that natural disturbances such as these are a way re-generating the forest and “resetting” the process of succession. Trees such as Tulip Tree and Red Maple that won’t grow under a dense, shady canopy can now get a toehold and will quickly fill the gap and add to the species diversity in the forest. Over time disturbances like these create a mosaic of variously aged shrubs and trees, making a forest a dynamic, ever changing ecosystem.

Ramblers examine a large tip-up

Not all the changes that occur as a result of storms are in the canopy. The soil surface is also reconfigured when a large tree tips over and uproots. Its root mat with clinging soil is now held more or less perpendicular to the ground, eventually forming a mound, and a hole up to several feet in diameter is left behind–an effect called “pit and mound topography” or “Pillow and Cradle” topography (or microtopography). The exposed bare soil creates all new conditions for seed germination, animal habitation, and water retention. The pits and mounds can persist in cool forests for hundreds of years.

The core of the Sycamore seed head

Sycamore fruit or seed head

Dissected Sycamore seed head

At the bottom of the path, we stopped to look at American Sycamore seed balls and the now empty cores remaining after all of the seed had been dispersed. Seed balls are a study in packing...many, many seeds are packed into the spherical mass. Unlike Sweet Gum balls, which are spiny and hold their tiny seeds in holes on the fruit surface, Sycamore balls are soft and easily separate into individual seeds (actually a dry fruit type called an achene), each tipped with tawny-colored hairs. (To understand how the seeds are arranged imagine the core of the seed ball as a disco mirror ball. Now imagine gluing the end of a small whisk broom handle to each mirror. The handle represent the seed, the broom part the tan colored hairs.)

American Sycamores have one seed ball hanging from a stalk, while the common street tree, London Planetree, has two seed balls at the tip of the stalk.

Sycamore bark is immediately recognizable – it sloughs off in patches, leaving a camouflage-like pattern on the trunk. Bark on all trees has to keep up with the growth in diameter of the trunk. Sycamore bark is inflexible and rather than spread and stretch, it flakes off. But only the younger parts of the trunk and branches have the white and tan mottled bark. As the tree ages the lower trunk develops dark, ridged bark that looks completely different from the younger parts of the tree.

Is that a big leaf, or what?

As we neared the stone bridge, we stopped to talk about Big Leaf Magnolia. Several large leaves were found on the ground. Big Leaf Magnolia has the largest single, simple leaf of any tree in North America.

Several Ramblers asked about a wood sorrel growing beside the path. White Wood Sorrel is native to meadows in Bhutan, China, India and Japan, and is widely planted in gardens throughout the south.

Before entering the Dunson Garden, we passed an extremely fragrant, blooming Tea Olive, its small white flowers releasing a wonderful perfume. It is a close relative of our native evergreen shrub (but not fragrant) American Wild Olive (aka Devilwood) that occurs in the Coastal Plain.

Dunson Native Flora Garden:

Jack-in-the-Pulpit infructescence

We saw several ripened infructescences (fruit clusters) of Jack-in-the-Pulpit, looking like large, plump red raspberries. We didn't see any plants but they may have gotten smashed by one of the many fallen trees in the Garden. The bright red fruits are loaded with calcium oxalate crystals, as are the leaves and stems. These crystals will seriously irritate the inside of your mouth, and probably your gut too. [I can tell you from my personal experience that they will never get to your esophagus – you'll spit them out first. DLH] Without an intensive drying process, the fruits are inedible by humans and other mammals. However, some birds, such as Wood Thrush and Wild Turkey, do eat the fruit. For more information about Jack-in-the-pulpit check here and here.

Cranefly orchid leaf, upper surface

Cranefly orchid leaf, lower surface

Linda pointed out fresh Cranefly Orchid leaves emerging from the leaf litter. These plants flowered in July (see the July 27, 2017 Ramble Report). The plant consists of a single pleated leaf–green on top, purple beneath, and usually punctuated with small black pits – rising from a fleshy underground storage organ called a corm. The leaf appears in autumn as the leaves begin to fall and conducts a year’s worth of photosynthesis throughout the fall and winter as sunlight makes it to the forest floor. The leaf begins to break down in the spring and, by the time the flowers emerge in mid-summer, is completely absent.

Linda practices her karate chop on an innocent Hophornbeam

At the same location, we noticed an unusual American Hop Hornbeam tree. The trunk splits about four feet above the ground, forming a two-foot keyhole in the trunk, which is intact above the keyhole. Several theories were thrown out about the origin of this oddity, including:  the growing tip of the young tree was damaged and separated into two trunks that later grew together; OR, there were originally two small trees that fused at their bases, separated after a few years, then grew together.

Rosemary made another exciting discovery: a firefly larva resting on vegetation! This is a very unusual thing to see. The larvae of fireflies (also known as lightning bugs) live in moist areas in and under the leaf litter. They spend one to two years in the larval stage before pupating. During that time they are predators on . . . SNAILS! (Also slugs, earthworms and soft-bodied insects.)

Mimsie Lanier Center:

American Lady on Georgia Aster

White Checkered Skipper on Georgia Aster

Georgia Aster

After leaving the Dunson Garden, we walked directly to the Georgia Aster patch at the Mimsie Lanier Center. Linda talked about Georgia Aster’s legal status as a federal candidate, and the Candidate Conservation Agreement that was crafted to protect the plant informally rather than legally. Don pointed out many of the twenty-plus species of pollinators he photographed and identified during his three visits in the past week.

Hooded Owlet moth caterpillar; note the red stripe
(photo courtesy of Rosemary Woodel)

Same caterpillar as above, different angle
note that the lateral stripe, with is red in the photo above, appears orange here
(it is barely visible on the lower edge of the caterpillar)

Rosemary found a Hooded Owlet moth caterpillar on one of the Georgia Aster plants. Identifying moth caterpillars is often difficult and this colorful caterpillar is no exception. Compare Don's photo with the one Rosemary took. Same caterpillar, different angle. The brilliant red stripe on the side in Rosemary's photo can't be seen in Don's, where there is the slightest suggestion of an orange stripe. It's possible that the viewing angle is responsible for the difference in perceived color. This ambiguity makes it difficult to determine which species of Cucullia this caterpillar is. The best matches are: C. alfarata, the Camphorweed Hooded Moth, or the Brown-hooded Owlet moth (Cucullia convexipennis).

No matter what the correct name is, the caterpillar is very conspicuous and was sitting on top of aster in full view. Most caterpillars are careful to hide, given that the world is full of predatory birds and parasitic wasps. Those that are protected from predation because they are distasteful or poisonous or have stinging bristles are often resting in exposed places. Could the Hooded Owlet moths be distasteful? They are noted to feed on a variety of Asters and Goldenrods, but those plants aren't noted for being distasteful or generally harboring toxic substances. So the brief answer is that we don't really know.

Clasping Aster, a close look-alike of Georgia Aster, is growing at the eastern end of the Georgia Aster patch. There is no apparent hybridization between the two.

Poplar Petiole Galls
The slits allow the aphids to leave the gall when they are mature.

There is a large Cottonwood  tree near the Georgia Asters so we looked at its triangular, delta-shaped leaves with their flattened petioles that cause the leaves to flutter in the breeze in a characteristic manner. The Western tree, Quaking Aspen, which is also a Poplar, derives its common name from that leaf motion. We  found several fallen [eaves with Poplar Petiole Galls. These galls are caused by the Poplar Petiolegall aphid. Here is a very nice video of the aphids inhabiting a petiole gall of cottonwood. Like the aphids that form the cone-shaped galls on Witch Hazel, the petiolegall aphids have two hosts that they alternate between. When the winged aphids leave the cottonwood tree they fly to the roots of a mustard family plant (Brassicaceae) where they feed and reproduce. Winged forms then fly back to the Cottonwood and lay eggs that hatch when the leaves emerge from their buds in spring.

SUMMARY OF OBSERVED SPECIES:

Loblolly Pine	Pinus taeda
Virginia Creeper	Parthenocissus quinquefolia
Sasanqua Camellia	Camellia sasanqua
American Sycamore	Platanus occidentalis
Big Leaf Magnolia	Magnolia macrophylla
Tea Olive	Osmanthus fragrans
Garden Snail?	Cornu aspersum?
Jack-in-the-Pulpit	Arisaema triphyllum
Cranefly Orchid	Tipularia discolor
American Hophornbeam	Ostrya virginiana
Lightning Bug	Family Lampyridae
Georgia Aster	Symphyotrichum georgianum
American Lady Butterfly	Vanessa virginiensis
Gulf Fritillary Butterfly	Agraulis vanillae
Eastern Bumble Bee	Bombus impatiens
American Hover Fly	Eupeodes americanus
White Checkered Skipper	Pyrgus albescens
Fiery Skipper	Hylephila phyleus
Sleepy Orange	Abaeis nicippe
Cucullia Moth Caterpillar	Cucullia sp.
Clasping Aster	Symphyotrichum patens
Eastern Cottonwood	Populus deltoides
Poplar Petiolegall Aphid	Pemphigus populitransversus