Ramble Report July 26 2018

Today's Ramble was led by Linda Chafin.

Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don.)

Today's post was written by Linda Chafin & Dale Hoyt.

Today’s Focus:

26 Ramblers met today.

Announcements:

Congaree National Park field trip: A small group of Ramblers decided to visit Congaree National Park, outside of Columbia, SC, Nov. 9 – 11, 2018, stimulated by a recent article in the New York Times. If any other Ramblers are interested in joining us you can find more details on our Announcements page.

Nature Rambler book club: Linda and Dale have been talking about a book club that would focus on “nature” books, broadly defined. Before we get started we need to find a free place to meet once a month. If you know of such a venue please email suggestions with the Subject line “NR book club,” to Dale.

Catalpa "worm" (really a caterpillar)

Show & Tell: Gary brought in a “catalpa worm” aka “catawba
worm” which is actually a caterpillar of a Hawk Moth (also known as Sphinx Moths). The adult moth lays its eggs on Catalpa Tree leaves and the caterpillars emerge 5-7 days later. They are capable of completely defoliating a tree several times during a summer, but the trees recover. Catalpa worms, known as “catfish candy,” are popular for fishing and can be frozen and thawed for fishing later in the year.

Today's reading: Linda read this poem by David Wagoner:

Lost

Stand still. The trees ahead and bushes beside you

Are not lost. Wherever you are is called Here,

And you must treat it as a powerful stranger,

Must ask permission to know it and be known.

The forest breathes. Listen. It answers,

I have made this place around you.

If you leave it, you may come back again, saying Here.

No two trees are the same to Raven.

No two branches are the same to Wren.

If what a tree or a bush does is lost on you,

You are surely lost. Stand still. The forest knows

Where you are. You must let it find you.

Today's route: We left the Visitor Center, via the back door, and headed across the Herb and Physic Garden to the head of the Purple Trail by the sod-roofed garden shack.  We took the Purple Trail all the way to the river and turned left on to the Orange Trail, which we took down the river and around the beaver pond.  At this point we returned the way we came back to the Cafe Botanica in the Visitor Center.

Jimson Weed flower

Jimson Weed fruit

Jimson Weed is planted in the Herb and Physic Garden because it was used by Native  Americans to treat asthma. It has also been used as a hallucinogen but this is very risky–the difference between a toxic dose and a psychoactive dose is very small. The sweet-smelling flowers open at night, are pollinated by sphinx moths, and produce oval, spiny capsules. The common name is based on Jamestown, Virginia, where British soldiers “ate plentifully” of the plant and spent 11 days in a state of delirium, folly, and “innocence and good nature.” (From Wikipedia — Robert Beverley, Jr., The History and Present State of Virginia, Book II: Of the Natural Product and Conveniences in Its Unimprov'd State, Before the English Went Thither, 1705)

This link will give you access to an interesting paper that connects Datura with the discovery of three human disease syndromes.

Female Tiger Swallowtail
Note the blue frosting on the black margin of the hind wing.

Male Tiger Swallowtail
Note the absence of blue frosing on the black margin of the hind wing.

Dale captured a male Tiger Swallowtail and showed us how to tell male from female. This butterfly has a solid black band on the hindwing, indicating it is a male. A female would have a black band sporting dense blue scales on the upperside of the hindwing. Female Tiger Swallowtails have two color forms: one is black and yellow like the male and the other is all black.  Both of the female color variants have the blue pattern on the upper hindwing margin.

Northern Red Oak still standing; how long will this one last?

Staff at the Garden have noticed that a lot of large oaks have fallen during the last 10 years, and most of them are Northern Red Oaks. We saw several today that had been blown over along the trail. The speculation is that they were weakened during the severe drought of 2010-2012 and subsequent shorter droughts and are more vulnerable to wind-throw now. Research conducted at the Warnell School of Forestry at UGA showed that Northern Red Oak seedlings have a loss of growth, fecundity, and biomass when subjected to drought. Northern Red Oaks are very near their southern limit along the Atlantic Seaboard in Athens; their range ends around Macon. Given that drought and storm intensity are expected to increase over the next 30 years, it seems likely that we are witnessing the beginning of the end of Northern Red Oaks here in the Piedmont–large trees are dying and seedlings will have a hard time establishing. The species will persist in the north Georgia mountains and further north, but the loss of a species on the periphery of its range means a loss of genetic diversity.

References:

Cavender-Bares, J., M. Potts, E. Zacharias, and F.A. Bazzaz. 2000. Consequences of CO₂ and light interactions for leaf phenology, growth, and senescence in Quercus rubra. Global Change Biology 6(8): 877–887.

Bauweraerts, I., M. Ameye, T.M. Wertin, M.A. McGuire, R.O. Teskey, K. Steppe. 2014. Acclimation effects of heat waves and elevated CO₂ on gas exchange and chlorophyll fluorescence of northern red oak (Quercus rubra L.) seedlings. Plant Ecology 215(7): 733-746.

Chanterelle mushroom

False Turkey Tail

Today was a good day for spotting fungi: Chanterelles and other mushrooms on the soil, and False Turkey Tails on downed trees were abundant. Of course, what we see above ground is only a tiny fraction of the fungal body; the mushroom is the part that produces spores. The bulk of a fungus is underground–long white strands called hyphae collected together into a vast, much branched colony called a mycelium. Research over the last few decades has shown how important fungal colonies are to the health of the forest. By breaking down dead plant matter, they make nutrients available in the soil. By connecting trees to some non-photosynthetic (or semi-photosynthetic) shrub and herb species, they foster species diversity in the forest. Some of the most exciting research has been conducted by Dr. Suzanne Simard, forest ecologist at the University of British Columbia, who has investigated how trees communicate. She found that trees use the fungal web to purposely trade nutrients based on need, and not just between members of the same species, but also between very different trees such as conifers and flowering, broad-leaved trees. She has discovered that “mother trees” – older, taller trees in the forest – are networked with all the other trees in that part of the forest and act as hubs for the distribution of nutrients. You can watch her discuss her research here: 

https://www.ted.com/talks/suzanne_simard_how_trees_talk_to_each_other

http://www.ecology.com/2012/10/08/trees-communicate/

A Simard-like researcher is featured in the new Richard Powers novel, “The Overstory,” which tells the story of a group of people who all have passionate connections to trees.

We stopped to look at the Possum-haw Holly. Hollies are dioecious, with female and male flowers occurring on separate plants. This particular plant is male – we’ve seen it in flower in the spring and its flowers have only stamens. Also, we’ve never seen it bearing fruit. Hollies can often be spotted because of the presence of “short shoots.” All along the typical long branches, there are short, stubby shoots that grow about a millimeter a year–you can count the nodes (each representing a year’s growth) along the shoot. A cluster of leaves and flowers is usually held at the tip of the short shoot, and it’s believed that bringing the leaves and flowers into close proximity speeds up the movement of carbohydrates to the rapidly growing flowers and fruits. Short shoots are also thought to increase photosynthesis by placing leaves at different places all throughout the crown of the shrub, thereby capturing more of the sunshine throughout the day.

The sweet leaves of Horse-sugar

We noticed that the patch of Horse-sugar (or Sweet-leaf) seems to be expanding on both sides of the trail, presumably by the spread of underground stems since no flowers or fruits have ever been seen on these plants. Plants that grow in sunnier areas flower in early spring before new leaves emerge. The leaves over-winter, though they often turn a deep burgundy color before falling in the spring. Fresh leaves smell and taste like green apples when crushed. The species name “tinctoria” refers to its use as a dye plant–both leaves and bark yield a yellow dye.

We paused to think of Hugh and Carol Nourse, the first leaders of our group, as we passed the large Persimmon tree, known as “Hugh’s Persimmon,” that is downslope of the Purple Trail. Like the hollies, Persimmon is also dioecious. This tree has never produced fruit so we assume it’s a male tree, though no one has investigated the flowers which are held high in the crown. The nearly black, blocky bark looks like charcoal briquettes.

Silverbell fruit, but what kind of Silverbell?

Georgia has three species of Silverbell:  Two-winged Silverbell, Carolina Silverbell, and Four-winged Silverbell. The latter two species bear fruits that have four wings and can be distinguished by their shape. Carolina Silverbell fruits are broadest near the tip; Four-winged Silverbell fruits are broadest toward the middle. You can decide from Don’s photo of the fruit which of these species we saw today Young Silverbells are easy to recognize year-round by their bark which has vertical gray and tan stripes. Older trees, seen mostly in the mountains, have dark, almost grayish-purple bark but small branches in the crown will have the same stripes.

Water Hemlock in the beaver marsh

Water Hemlock (Cicuta maculata) is flourishing in the beaver marsh. From a distance it looks like Queen Anne’s Lace because it has the same type of inflorescence and dissected leaves. Both Water Hemlock and Queen Anne’s Lace are in the same family, along with many edible plants such as carrot, parsley, cumin, cilantro, dill, and fennel. But Water Hemlock is extremely toxic to humans and other animals, especially the roots, and eating even a tiny amount can be fatal or cause permanent damage to the nervous system. Water Hemlock is related to Poison Hemlock (Conium maculatum), a European species believed to be the plant used to execute Socrates, and the two look very similar.

Cranefly orchid flowers

Crane-fly Orchids are in bud and flower along the Purple Trail. A close look at the flowers reveals that they are slightly twisted either to the right or left. The flowers are pollinated by noctuid moths that probe the flowers for nectar and, in the process, bring their eyes into contact with a sticky packet of pollen (called a pollinia). The packet sticks to either the left or right eye of the moth, depending on which way the flower is twisted, and is carried to another flower and deposited during nectar-probing on the stigma of that flower. Dale described this type of pollination as “all or nothing” – instead of producing lots of loose pollen grains that may be picked up by several different visiting insects, all the pollen is packed inside the pollinia and is carried all together to another flower – or not. This may seem like a risky pollination strategy but the orchid family is the second largest plant family, so they must be doing something right.

Walnut sphinx caterpillar
A caterpillar that can "whistle."

A “Whistling” Caterpillar? On the Purple Trail we discovered a sphinx moth (= hawk moth) caterpillar. Most caterpillars in the sphinx family have a characteristic spine or horn projecting from their posterior end. The other unique feature of this insect is its pointed head. After passing it around we released it. Only later, when comparing Don’s photograph with some references did I discover that it was a Walnut Sphinx caterpillar, Amorpha juglandis. But wait! There’s more! It turns out that this kind of caterpillar can whistle! When attacked by a bird it emits a short sound, apparently to startle the attacker. You can download this short movie and play it on your computer to hear the sound produced. It’s not spectacular, but, hey, it is a caterpillar!

The sound is produced when the caterpillar pulls its head back towards its thorax, squeezing its abdomen. Each segment of the caterpillars body has a pair of opening, called spiracles. These are the openings of its respiratory system. When the body is contracted air is force out through one of the last pairs of spiracles, producing the noise.

Reference: Bura, V.L., Rohwer, V.G., Martin, P.R., and Yack, J.E. (2011). Whistling in caterpillars (Amorpha juglandis, Bombycoidea): sound-producing mechanism and function. Journal of Experimental Biology 214, 30–37.

Newborn Red-bellied snake

James found a newborn Red-bellied snake, Storeria occipitomaculata. This species can be confused with the Brown snake, Storeria dekayi, and the Ring-neck snake, Diadophis punctatus. All these are small, secretive snakes that feed on invertebrates. Both the Red-bellied and Brown snake are slug and snail specialists, but also eat other small creepy-crawlies. The Storeria snakes both have keeled scales and give birth to their young. Ring-neck has smooth scales and lays eggs. (Keeled scales have a ridge running down their center, smooth scales lack a ridge.) The belly color is tan in the Brown Snake, usually reddish orange in the Red-bellied and yellow with black dots running down the middle in the Ring-neck.

SUMMARY OF OBSERVED SPECIES

Plants
Jimson Weed	Datura stramonium
Japanese Stiltgrass	Microstegium vimineum
Northern Red Oak	Quercus rubra
Cranefly Orchid	Tipularia discolor
Horse Sugar	Symplocos tinctoria
Possumhaw	Ilex decidua
Hophornbeam	Ostrya virginiana
Sourwood	Oxydendrum arboreum
Silverbell	Halesia sp.
American Hornbeam, Musclewood	Carpinus caroliniana
Water Hemlock	Cicuta maculata
Animals
Katydid nymph	Family Tettigoniidae
Eastern Tiger Swallowtail	Papilio glaucus
Nine-banded Armadillo	Dasypus novemcinctus
Camel Cricket	Family Raphidophoridae
Earthworm	Annelida: Megadrilacea
Sphinx moth caterpillar	Family Sphingidae
Wood Thrush	Hylocichla mustelina
Scarlet Tanager	Piranga olivacea
Red-bellied Snake	Storeria occipitomaculata
Fungi (Mushrooms)
Coral or Tube Slime Mold	Ceratiomyxa fruticulosa
Yellow Pleated Parasol mushroom	Leucocoprinus bimbaumii
Chanterelle mushroom	Cantharellus cibarius
Gem-studded Puffball mushroom	Lycoperdon perlatum
Old Man of the Woods mushroom	Strobilomyces strobilaceus
False Turkeytail mushroom	Stereum ostrea
Jellied False Coral Mushroom	Tremellodendron pallidum
Wood ear mushroom	Auricularia auricula
Slime molds
Coral or Tube Slime Mold	Ceratiomyxa fruticulosa