Sunday, February 21, 2016

Ramble Report February 18 2016



 Here's the link to Don's Facebook album of today's Ramble. Today's post was written by Dale Hoyt.

Our first ramble of the year started with 32 Ramblers including 1 new rambler and 1 guest. This is a record turnout for us.

Today's readings

I read an excerpt from Nature Near Home by John Burroughs. This was one of Hugh's favorite passages. It reflected his belief, developed over the years he led our group. I wanted to read it on this, our first ramble without Hugh and Carol, as a tribute to Hugh's years of leadership. (I've changed some words, replacing he and his with more inclusive language.)

After long experience I am convinced that the best place to study nature is at one's own home, on the farm, in the mountains, on the plains, by the sea, no matter where that may be. You have it all about you then. The seasons bring to your door the great revolving cycle of wild life, floral and faunal, and you need miss no part of the show.
At home you should see and hear with more fondness and sympathy. Nature should touch you a little more closely there than anywhere else. You are better attuned to it than to strange scenes. The birds about your own door are your birds, the flowers in your own fields and wood are yours, the rainbow springs its magic arch across your valley, even the everlasting stars to which you lift your eye, night after night, and year after year, from your own doorstep, have something private and personal about them.  . . . The wild creatures about you become known to you as they cannot be known to a passer-by.  . . .The traveler sees little of Nature that is revealed to the home-stayer. You will find she has made her home where you have made yours, and intimacy with her there becomes easy. Familiarity with things about one should not dull the edge of curiosity or interest. The walk you take to-day through the fields and woods, or along the river-bank, is the walk you should take to-morrow, and next day, and next. What you miss once, you will hit upon next time. The happenings are at intervals and are irregular. The play of Nature has no fixed program. If she is not at home to-day, or is in a non-committal mood, call tomorrow, or next week.

Next, Don read a short passage from John Muir's Travels in Alaska:

“In every walk with Nature one receives far more than he seeks.”

Today's route: 

Leaving the arbor, we made our way past the Callaway Building and Amphitheater to the mulched north end of the White Trail Connector, and down to the Dunson Native Flora Garden.  Leaving the Dunson Garden, we made our way through the weed patch on the other side of the fence, then over to the power line right-of-way, where we headed down the ROW towards the river, stopping at a vernal pool.  We returned via the ROW and the south end of the White Trail Connector spur back to the parking lot and on to Donderos'.

North End of White Trail Connector, leaving the arbor parking lot:

We stopped to identify a young Sourwood tree, young enough to have not developed the highly ridged bark that is typical of this species. Linda pointed out that there were several root suckers at it's base, which is an indicator that the tree is diseased or in other difficulty. She also noted that the new shoots are reddish in color and that if you tasted them they would taste sour. Emily, no surprise there, immediately broke off a twig and chewed on it. Her conclusion: maybe or maybe not.

We took a quick look at an American beech with its diagnostic smooth gray bark and long, slender sharply pointed buds, both lateral and terminal. (Terminal buds are at the end of twigs; lateral buds form on the sides of the twig.)

Hawk's nest in crotch of White Oak tree
Then we heard the cry of a Red-shouldered hawk and Linda pointed out the nest that is under construction in a nearby White oak tree.

Dunson Native Flora Garden:

Alleghany spurge (AKA Pachysandra)
Entering the Dunson Garden we saw green leaves of several herbaceous plants: Alleghany spurge, Columbine, a Trillium (probably Trillium cuneatum) and White avens. Linda noted that the Alleghany spurge makes a nice, shade tolerant, ground cover. And, it's a native species!

Further along we stopped to look at the large, fuzzy terminal buds of Ashe's magnolia. This suggested the question: what is inside a bud? A bud contains an embryonic twig, complete with several leaves and/or flower buds. In Spring a bud loses its protective scales, which leave a scar on the twig where they were attached. By looking backward on the twig you can find the bud scar from the previous year and determine how much last years twig grew. After the bud scales fall off the newly revealed twig then begins rapid elongation, sometime growing as much as a foot or more in the following few months. As the twig elongates its embryonic leaves begin to expand. If there are any flower buds present they also develop. Some terminal buds just produce flowers – they show no growth after the flower develops. Other terminal buds produce flowers at the base of their developing leaves and in still other kinds of plants flowers are produced on lateral buds.This is why you have to be careful about when you prune a shrub. Some flower on the new growth of the current year while others flower on the previous years growth.
Nearby the magnolias Roger pointed out a Green and gold with a single yellow flower and
Sensitive fern reproductive fronds
Linda showed us the remainder of last falls Sensitive ferns reproductive fronds. The tiny dark knobs are the structures that produce spores (called sporangia). Near here we
Golden ragwort with flower buds
also found Golden ragwort with developing flower buds. The ragwort has two distinctly different leaves. The overwintering leaves are circular with a toothed edge, but the leaves on the flower-bearing stem that develops in spring are elongate and divided into many lateral lobes.Some of the overwintering leaves (see photo below) have light, wandering trails caused by leaf miners. These are insect larvae, either moths or flies, that feed on the tissue between the upper and lower epidermis of the leaf. They hatch from eggs laid on the leaf, burrow into the leaf and begin feeding. As they wander through their leaf they leave a trail without green tissue. As they grow is size the trail widens, making it possible to follow their life travels from beginning to end. At the widest point they will exit the leaf, drop to the ground and pupate. A whole world within a thin leaf!
Golden ragwort overwintering leaves with leaf mines
Lastly, we found two flowers of Sharp-lobed hepatica whose new leaves had not yet emerged. Last year's leaves are very senescent and ratty looking. This species is not the same as the hepatica we see growing on the Orange trail. In fact, the sharp-lobed hepatica naturally occurs in NW Georga where the soils are underlain by limestone rock, making them less acidic than the soils in this part of the piedmont.


Sharp-lobed hepatica (AKA LIverleaf)
Many plants, like the hepatica, have strange sounding names, at least to the modern ear. Linda explained that these names are often derived from the medieval Doctrine of Signatures. The belief was that God had created some plants to resemble human organs that were curative of diseases affecting these organs. Hepatica got it's name from the fact that the leaves have three lobes as does the human liver. (Hepatica, in Latin, means liver.) Other examples of the Doctrine of Signatures can be found in names such as Toothwort and Spleenwort (the suffix –wort is from old English and simply means "herb" or "plant." The Doctrine of Signatures held sway for centuries, probably as a result of a placebo effect and the fact that most illnesses run their course for a week or so. If you get sick and wait a week before you see a doctor you probably would have recovered without the prescribed medicine, but the medication gets the credit when you recover

At the nearby bridge in the Dunson Garden there are two young Sycamore trees that have wonderfully patterned bark in shades of gray, green and white. When you see older Sycamores that colorful bark will only be seen on the upper reaches of the trunk and limbs – the base of the tree develops a more typical dark, ridged bark. The older the tree the higher up the dark bark extends.

Linda pointed out a "Witches broom" on a Hop hornbeam tree. This is a scraggly bundle of small twigs that emerge from a short region of a tree limb. It is caused by an infectious agent like a fungus. In the Botanical Garden we frequently find Witches brooms on Hop hornbeams, but they can be found on other trees as well.

Leatherwood flower
Notably we discovered that the Leatherwood shrubs have started to bloom. Last year, near this time, we found honeybees visiting the Leatherwood flowers, but none were seen today.

Along the path we sighted several Cranefly orchid leaves. This orchid has the unusual habit of producing a single leaf during the winter. The leaf ages and disappears toward the end of spring. Then, in late summer, a flower stalk bearing dozens of tiny orchids emerges from the ground.

A Frost flower on the stem of a weed
As we left the Dunson Garden Don led us on a hunt for Frost flowers. The sun was barely touching the weedy hillside and there were still a few that had not melted. (The Frost flower is not a flower – it is an ice formation that is only seen when the overnight temperature falls below freezing. Water is extruded from the stem of a weed and freezes into interesting curving patterns that melt as soon as the air temperature rises above the freezing point. They commonly are found on White crownbeard, also called, appropriately, Frostweed, but is less common on other plants.

An enormous puffball
On the way out of the weed patch Don discovered an enormous Purple puffball, almost as large as his head.
Flood plain, Power line right-of-way:

Ramblers watching soaring vultures
Several people spotted two kinds of vultures soaring overhead: Turkey vulture and Black vulture. Turkey vultures have a keen sense of smell and can detect the odor of dead animals even if they are hidden from sight. They often are the first to discover carrion. The Black vulture will often arrive late to the scene and displaces them from the prize the Turkey vultures discovered.

On the east side of the right-of-way there is a low place where water often collects during
American toad egg strings
the tiny black objects clinging to the jelly are hatched tadpoles
the winter. Two and a half days ago I visited it and found no signs of amphibian activity. This morning we found the coiled strands of eggs laid by American toads and several large egg masses that I thought could either be laid by salamanders or leopard frogs. After the ramble
Southern leopard frog egg mass
I collected a small piece from one of the larger egg masses to take home and photograph. I'm now confident that the large egg masses were laid by Southern Leopard frogs, Rana (Lithobates) sphenocephala; and the long, coiled tubes are the egg masses of the American toad, Bufo (Anaxyrus) americanus.

While some ramblers were looking at frog eggs Linda told us about a frog call CD that is available from the Georgia Department of Natural Resources. This recording and accompanying book will help you learn to identify the calls of over two dozen frogs found in our state. Frog calls are easy to learn because they are usually simple and stereotyped, not nearly as complex and variable as bird calls can be. You can impress your friends and loved ones with your ability to speak frog if you just purchase and study this CD and booklet.
You can also hear the calls of many Georgia frog and toad species (and Alligators) at this website.

Ephemeral wetlands

The wet areas in the flood plain are ephemeral, meaning that they do not retain water all year. This intermittent dryness makes them attractive to amphibians, because it means that they do not contain fish. Fish prey on amphibian larvae and frog and toad tadpoles will have a difficult time surving in water with fish. But the temporary nature of ephemeral pools has a downside -- will the water remain long enough to allow amphibians to complete their development? These standing pools of water form after rains, but they persist longer during the winter and spring months. The same pools also form after heavy summer rains, but they dry up very rapidly. The reason is not directly due to the higher temperatures of summer, although that has an effect. It is the vegetation. The trees, grasses, herbs and shrubs that grow in the flood plain are dormant during the winter but actively growing in the spring and summer. As plant growth is renewed the water in the soil is drawn up through the roots and carried to the leaves where it evaporates. This is a process called "transpiration." This invisible stream of water, moving through millions of root systems, carries with it mineral nutrients from the soil up to the photosynthetic machinery of the leaves where the energy of sunlight binds the nutrients into organic form. It is the evaporation of water from the leaves that makes plant growth possible. Transpiration effectively pulls the water out of the soil. That evaporated water is replaced by water in the soil drawn from the water table, so as plants grow, making more plant tissue, the water table must fall. This is why water can accumulate in temporary pools during the winter and why those pools must vanish during the coming spring. 

The removal of the privet from the levee area of the Orange trail should have a huge impact on the retention of water in the flood plain. I previous years with rampant privet growth that area frequently dried up. It will be interesting to see how much water is retained now that the privet is gone. (Because privet is evergreen it continued transpiration during the winter months when native plants would be inactive.)

The temporary nature of such wetlands makes them especially attractive to amphibians. Because they are temporary, they do not harbor predators like fish, making them good places for tadpoles to thrive. What one hand gives the other taketh away. The frogs get a relatively secure place for their offspring, but at the expense of forcing them to develop rapidly. It's like finding an inexpensive furnished apartment and discovering that the building is going to be torn down. It's not surprising that the frogs that breed in this type of environment develop from egg to tadpole to adult in a few short months. For some it is a race that is not won every year. Frogs with longer developmental times, like the Green frog, Rana (Lithobates) clamitans, cannot successfully breed in such wetlands. They require permanent water, such as is found in the Beaver pond/marsh found next to the Orange trail in Garden.

The frog eggs stimulated a lot of questions that I'll attempt to summarize and answer here.

Who laid these eggs?

Initially I thought that the large egg masses could have been laid by either salamanders or leopard frogs. I took home a sample and examined them under a dissecting microscope. I'm now confident that they were not laid by salamanders and their subsequent development confirms this. First, salamander eggs masses are smaller and don't have as many eggs. Second, salamander eggs are generally larger that frog eggs and these are too small (the egg proper, not including the jelly coat). So, if they are frog eggs, which kind of frog laid them? The early breeding frogs in this area are Southern leopard frogs, Spring peepers and Chorus frogs. Of these, peepers lay their eggs a few at a time, scattered in the litter, Chorus frogs lay eggs in small masses wrapped around grass blades and leopard frogs lay large masses of eggs in shallow waters, wrapped around vegetation. So these are probably Southern leopard frog eggs. The possible pond breeding salamanders in this area are the Spotted salamander, Mole salamander and Marbled salamander. Of these, the Marbled salamander can be excluded because they lay eggs in the fall, under logs or leafy debris in areas that are likely to be flooded by late fall/winter rains. Spotted salamanders gather in large aggregations for mating and the egg masses that they produce are smaller than those that we saw, with larger eggs and embryos.

The other type of egg mass, the coiled strands of dirty jelly embedded eggs, is typical of the American toad, the early breeding toad in this area.

The facts of life for frogs and toads and salamanders

First, frogs and toads. When breeding season arrives male frogs congregate in a suitable location, like a pond of small pool of water, and begin calling to attract females. Those calls are species specific, just as bird calls are. You can learn to identify frogs from their calls. Female frogs are attracted to the voices of their own species and migrate toward the sound of the calling males. As she enters the pond she encounters a male who immediately grasps her from above, tightly gripping her with his forearms, his hands balled up and squeezed into her arm pits. The breeding pair, male riding on her back, will now be carried around by the female, searching for a suitable place to lay her eggs. When she finds a place she begins to extrude jelly coated eggs from her vent. As the eggs emerge the male brings his vent close to them and emits sperm, fertilizing the eggs as they emerge from the female. This process continues until the female has laid all her mature eggs, which in some cases can number a thousand or more. Smaller frogs usually produce a lower number of eggs – a hundred or fewer.

Salamander reproduction differs from frogs. In the typical salamander fertilization of the eggs is internal, happening inside the female's body. In most salamanders the males do not clasp the females. Males produce a spermatophore, a short, gelatinous structure that is capped with a package of sperm. The female walks over the spermatophore and picks off the top part that contains the sperm. She then will lay several egg masses, somehow using the stored sperm to fertilize them before attaching them to submerged vegetation.

Where does the jelly come from?

The jelly that covers amphibian eggs is produced by glands in the oviducts of the female. As mature eggs leave the ovaries they move through the oviducts and the glands secrete a jelly that coats them as they pass by. This jelly is just a thin mucous layer that will absorb water and swell up when the eggs leave the females body. In toads the jelly is produced in a continuous cylinder that surrounds the eggs and when it leaves the body becomes the a long string of jelly-encased eggs, one from each oviduct. As the female toad lays her eggs she walks forward. The jelly coat is sticky and adheres to sticks, grasses or twigs in the water and stretches out as she walks away. Leopard frog eggs are individually wrapped in a sphere of jelly. As the female lays her eggs she remains still and gathers her eggs with her hind legs and presses them against grasses or other vegetation in the pool. As the jelly surrounding each egg absorbs water and swells the eggs adhere to one another, forming a single large mass.

How long before the eggs hatch?

The rate of development depends on the temperature of the water. The lower the temperature the slower the egg will develop. Eggs deposited in shallow, sunny places will experience higher temperatures and will develop faster. That's probably why all the leopard frog egg masses we saw were clustered together at the very shallow edge of the pool. It may take a week or more for them to hatch.

How frog eggs are laid

The American toad lays its eggs in a pair of long strings that can be coiled like the extension cord on a telephone handset (if anyone remembers those). Ripe eggs emerge from the two ovaries (one on the left and one on the right) and pass into the two oviducts that will encase them in the jelly coating. As the eggs pass down the oviduct they are encased in a thin layer of jelly secreted by glands in the oviduct walls. As the egg strings emerge from the body of the toad they are fertilized by the male that is clasping the female. The jelly-coated egg string rapidly absorbs water and swells to form a thick, viscous cylinder that surrounds each of the eggs. As the female toad lays her eggs she walks forward. The egg string sometimes catches on vegetation and stretches out as she goes. If it doesn't catch on anything it gets dragged along and the jelly picks up a coating of mud and debris from the floor of the pool. That's why it is hard to see anything inside the jelly strings/cords that we saw this morning – the jelly coats picked up a lot of mud.

The Southern leopard frog egg masses appear to be more recently deposited than the toad eggs. I base this conclusion on the relative developmental stage of the embryos. The toad embryos have reached the tail bud stage whereas the frog eggs are earlier embryos – their nervous system has begun development but the tail bud has not yet emerged.

The difference in the appearance of the egg masses is due to two things: the way the frog lays its eggs and the way the jelly is produced. The leopard frog female remains stationary and as the eggs are extruded and fertilized she keeps them together with her hind legs instead of walking forward like the toad. In addition each egg is coated with an independent jelly coat instead of being imbedded in a long cylinder of jelly.

Leopard frog embryo still encased in jelly envelope
The Leopard frog egg jelly envelope in the photo above is 1/4 inch in diameter. The dark object in the middle of the jelly sphere is the frog embryo. The head is beginning to form (on the bottom side of the photo) and the beginning of a tail bud is forming on the other end.


Toad embryo

The photo above is of an American toad embryo that I removed from its jelly envelope. The head is to the left, the tail bud toward the right. The embryo is only about 1/8th inch long at this stage of development. It's growth is supported by the yolk present in the egg. The remnants of that yolk are seen in the slightly swollen belly. The bump at the bottom of the head is an adhesive gland that will allow the embryo to attach itself to objects in the water after it has hatched but before its development as a tadpole is complete. At this stage of development the eyes are beginning to form and the embryo can only twitch a little if it is touched. Toad development proceeds more rapidly than Leopard frogs. The toad eggs I photographed on Thursday have all hatched by now (Sunday AM) but the Leopard frog embryos are just now showing elongated tail buds.

If you have other questions about frog and salamander reproduction don't hesitate to ask me.

Back to the arbor on the White Trail Connector Trail

Rue anemone
One of the other surprises was the discovery of some blooming Rue anemone flowers at the beginning of the trail. This area supports a large population of Rue anemone, but we have never seen them blooming here this early. The common name of this plant is strange to most people. The "Rue" is a reference to another plant, Early meadow rue, that has similarly shaped leaves. Thus this is an anemone with leaves that look like a rue.

SUMMARY OF OBSERVED SPECIES:

Sourwood
Oxydendrum arboreum
American beech
Fagus grandifolia
Red shouldered hawk
Buteo lineatus
Alleghany spurge
Pachysandra procumbens
Columbine
Aquilegia canadensis
Trillium
Trillium cuneatum.
White avens
Geum canadense
Ashe's magnolia
Magnolia ashei
Green-and-gold
Chrysogonum virginianum
Sensitive fern
Onoclea sensibilis
Sharp-lobed hepatica
Anemone acutiloba
American sycamore
Platanus occidentalis
Hophornbeam
Ostrya virginiana
Cranefly orchid
Tipularia discolor
Leatherwood
Dirca palustris
Painted buckeye patch
Aesculus sylvatica
Purple-spored puffball
Calvatia cyathiformis
Turkey vulture
Coragyps atratus
Black vulture
Cathartes aura
Southern Leopard frog
Rana (Lithobates) sphenocephala
White tailed deer
Odocoileus virginianus
American toad
Bufo (Anaxyrus) americanus
Eastern bluebird
Sialia sialis
Violet
Viola sp.
Rue anemone
Thalictrum thalictroides


5 comments:

  1. If only I could remember your careful analysis of salamanders vs frogs

    ReplyDelete
  2. The original post mis-identified the hawk nest as that of a Red-tailed hawk. It is a Red shouldered hawk nest. I've changed all occurrences.

    ReplyDelete
  3. Dale, awesome post. Really appreciate the effort you put into these descriptions and the quality of Don's photos. The link to the frog calls was fun.
    FWIW, the Georgia Frog CD "Calls of the Wild" can be ordered here for $14.84:
    http://www.georgiawildlife.org/node/682

    ReplyDelete
  4. AARRGH. No sooner did I press send than I realized the DNR link was already in your post. Wiping egg from face.

    ReplyDelete
  5. Wow! This is a fantastic recap of an excellent morning. Many thanks to you and Don for your efforts.

    ReplyDelete

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