Tuesday, November 24, 2015

Frost flowers at the State Botanical Garden of Georgia

This morning (Nov. 24) Emily and I drove out to the Bot Garden to look for "frost flowers." We found some during our Nature Rambles in the Garden last year (see this link) and the year before (2013, at this link). They only appear (or we only look for them) on the first autumn day when the overnight temperature is below freezing, which is a clue to their origin. They are not flowers, but some do look flower-like. They are, in fact, ice that appears to have been formed from water that is forced out of the stems of certain plants. As the water extrudes it freezes, forming a delicate ribbon of ice that twists and turns into a variety of interesting shapes. You can only observe these ephemeral structures for a short period of time. When the sun hits them they rapidly melt away.

This morning we found the greatest concentration of frost flowers at the bottom of the Dunson Native Flora garden just outside the fence that separates the Yucca planting from the "weeds." Earlier this summer most of the plants growing in this area were White crownbeard (Verbesina virginiana), also known as "Frostweed." Because there are two other species of Verbesina growing in this area of the garden we thought it would be interesting to see if any of them had produced frost flowers. We walked on the path in the power line right of way toward the river, checking the stems on either side and saw no evidence of frost flowers.This part of the garden has both V. alternifolia and V. occidentalis in abundance, so the absence of frost flowers here means that they may not be suitable for their formation. (Or that we were too late and the sun had melted them all.)

If you would like to see the growth and demise of a frost flower view this time-lapse video.

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 fluid in the plant 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 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.”.

John and his brother Joseph were native Georgians, educated at Harvard and Yale, who became Professors at the University of Georgia, but left after an acrimonious dispute with the then president, Alonzo Church. Church thought that Professors should only teach, but the LeConte brothers wanted to both teach and do research. Both brothers left UGA over the dispute and eventually found their way to University of California where John became President.

If you want to see this phenomenon for yourself wait until the overnight temperatures are below freezing and go to the Bot Garden early (the grounds and natural areas are open at 8AM), before the sun is too high. It would be interesting to see if the same plant can produce a frost flower more than once. You could determine this by tying a marker to a specific plant and observing it on successive days when the conditions are right.

I hope you all have a great Thanksgiving!


Friday, November 20, 2015

Ramble Report November 19 2015

Today's report was written by Hugh Nourse. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.


  1.     Emily is putting in the T-shirt order tomorrow, so if you wish to purchase one you need to get your money and order to her quickly. 
  2.    There is a special ramble on December 3, the Thursday after Thanksgiving, on Herbarium Specimens. Wendy Zomlefer, the Curator of the UGA Herbarium will demonstrate how herbarium specimens are prepared, and let us press a few plants ourselves.
  3.     Walt Cook will be leading a walk at Sandy Creek Nature Center on December 2, at 9:00AM, the first Wednesday in December.
4.    Update to the Hike Inn opportunity:
  • Ramblers can send an e-mail to "reservations@hike-inn.com" with their name, phone contact information, and "January 27 Georgia Forest Watch." The Reservation clerk will then call back. We cannot book our room through e-mail messages, but it helps reduce the phone tag.
  • The Hike Inn has reserved all rooms for Ramblers at this time.
  • The cost is a little more than quoted in the notice you received: Double occupancy, $102.75; Single occupnacy, $72.28
  • ·         [Note: Jackie Elsner is the person responsible for initiating this field trip; I am just the guy that sends out the emails. Give her the credit, not me. -- DH]

Tuesday, November 17, 2015

Nature Rambler Tshirt Order Form

Click here for the T-shirt order form. Print the order form, fill it out, and follow the instructions.

Here is a mock-up of the Nature Rambler T-shirt.   

The actual color of the T-shirt is Pistachio and, in life, it looks greener than the one displayed on your monitor. To see the color on the website go to this link.

Friday, November 13, 2015

Ramble Report November 12 2015

Today's report was written by Dale Hoyt. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.

Thirty one ramblers met this cool, partly cloudy morning.

Before the reading there were some announcements:

1) Remember 
Next week is the last regular ramble of this year. But, the Thursday following Thanksgiving we will have a special ramble conducted by Wendy Zomlefer, the curator of the UGA Herbarium. That will meet at 8:30AM in the Gardenside Room of the visitor center. There will be donuts, so you might want to skip breakfast.

Friday, November 6, 2015

Ramble Report November 5 2015

Today's report was written by Hugh Nourse. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.

Twenty-four Ramblers met under the Arbor at 8:30 AM.  Sue showed everyone the Guide to Invasive Plants by the Dept. of Agriculture, and told how to obtain either a hard copy from the Dept., or by downloading a free PDF. I believe you do this at the USDA Forest Service web site.  Catherine brought a box full of bur oak acorns which she distributed to anyone who wanted one.  It was an acorn with a very large frilly cap.

Hugh shared a reading from Andrea Wulf, The Brother Gardeners:  Botany, Empire and the Birth of an Obsession, pp. 88-89.

Sunday, November 1, 2015

Ramble Report October 29 2015

Today's report was written by Dale Hoyt. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.

Today's reading was the entry for October 31 in An Almanac for Moderns by Donald Culross Peattie:

Friday, October 23, 2015

Ramble Report October 22 2015

Today's report was written by Hugh Nourse. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.

Twenty-one Ramblers assembled at  8:30AM at the Arbor by the Lower Parking Lot.  The forecast was for 79 degrees later in the day, so many dressed for that, but the temperature at 8:30 was about 45 degrees. Some were a bit chilly!

Catherine read from Who named the daisy, who named the rose, a roving dictionary of North American Wildflowers by Mary Durant.  The topic was the etymology of witch hazel:

Saturday, October 17, 2015

Ramble Report October 15 2015

Today's report was written by Dale Hoyt. Most of the photos that appear in this blog are taken by Don Hunter; you can see all the photos Don took of today's Ramble here.

We had twenty four Ramblers today: the usual regulars plus some out-of-town guests and a new rambler.

Today's reading was an entry about autumn from Donald Culross Peattie's An Almanac for Moderns:

The north woods have somehow stolen the fame of autumnal glory from other quarters of the land. But what have they – maples and beeches and aspens and rowanberry – that we have not? Or their fiery viburnums or buckle-berries or brambles? We have all their colors and more, and indeed it is the tropical element in our flora that imparts the most dazzling brilliance. The tupelo tree before my door and the persimmons across the valley glow with a somber anger, like leaves that would be evergreen if they might and turn to the color of smoldering charcoal only under compulsion. The sassafras and the sour gum shout with orange and scarlet, and the curious sweet gum, with its star-shaped leaves, exults in crimson and vermilions. Like the gold tulip tree leaf it has a look about it as of some vegetation that does not really belong in the flora of the world today.

And in truth they both, like so many of our trees, are sole survivors of once great families of ages past. In what autumns must the Tertiary have rejoiced, when leaves that are fossils now flamed with colors we can only imagine – flamed upon a world without men in it, to call it beautiful.

rowanberry = Mountain ash (which is not an ash)
buckle berries = any sweet summer berry, e.g., blueberries, that can be baked in a dish called a buckle (it's something like a crumble).
tupelo = Black Gum, Sour Gum

Today's route: We attempted to walk the same route as we did last year, but didn't get quite as far. Through the International garden to the Purple trail. Down the Purple trail to the Orange trail at the river. Left on the Orange trail to the bridge back through the flower garden and thence to the Conservatory.

Bob is looking at two root suckers from the Pawpaw in the background
Pawpaw patch. All the tall wildflowers at the beginning of the International garden have been cut back and it looks comparatively naked now. With the flowers gone we noticed a tree that previously had escaped our attention: a Pawpaw with two root suckers. Pawpaw has delicious fruit but it doesn't last long after it ripens and cannot be shipped. Consequently, most people have never had the opportunity to sample it. It has a propensity to form root suckers, so where one grows soon there will be a whole patch. I planted three in our backyard a number of years ago and two of them have produced nine suckers. I have yet to get any fruit – it keeps disappearing just before it is ripe. Squirrels, Raccoons or Opossums are the likely culprits.

Chinese tea plant blossom
Chinese tea. The Chinese tea (Camellia sinensis) is currently blooming and we stopped to look at the flowers and hear about the influence tea has had on world history. Tea was introduced to the British in the middle of the 17th century and became the preferred source of caffeine there. At the time China was far more advanced than Europe. European traders desired the tea, silk and porcelains available only from the Chinese but had little that the Chinese wanted or needed. The Chinese traders insisted on precious metals in exchange for their tea, which gave an advantage to the Spanish, who had plenty of gold and silver from their mines in Mexico and South America. The British solution was to illegally smuggle opium that was produced in India by the British East India Company. The British got their tea and the influx of illegal opium destabilized the Chinese government. In the mid-19th century the Opium Wars resulted in the forced opening of China to trade with the west, which meant a free flow of opium into the country. Some attribute the influx of cheap opium and the resulting high rate of addiction as paving the way to the further decline of the Chinese government and opening it up to the successful Communist takeover following WWII.

And then there was the kerfuffle over the taxation on tea in the British American colonies, leading to the independence of the United States as well as the emergence of coffee as America's favorite source of caffeine.

Sapsucker sap wells on Hophornbeam
Tiny mushrooms are also visible

Hop hornbeam and Yellow bellied Sapsuckers. Near the top of the Purple trail is a Hop hornbeam with a series of holes punched in its bark. The holes are produced by a type of woodpecker, the Yellow Bellied Sapsucker. These birds spend the winter here and places further south. They peck small holes in the bark of several types of trees, penetrating to the sapwood. These sap wells, as they are called, fill with a dilute sugary solution that the sapsuckers feed on and that also attracts insects, which the sapsuckers also eat. Eventually the tree seals off the sap wells and the sapsucker makes another series of holes. If you look at this tree you can see that it has holes reaching upward as far as the eye can see. In the Botanical Garden we find sapsucker holes most often on Hop hornbeams, but other trees can be utilized. In my neighborhood we find them on pecans.

This Hop hornbeam also has tiny mushrooms growing on its bark. When it is raining they expand and shrink back down when it dries out.

Horse sugar. Further along the Purple trail, on the left, is a small group of Horse sugar. Hugh always remarks on these, telling us that he has never seen them in bloom. They never seem to grow much and we suspect that the combination of deer browsing location under the canopy of leaves overhead may cause the retarded growth. Horse sugar can grow to tree size – there is a large one at Sandy Creek Nature Center that flowers profusely in the spring. The common name comes from the fact that the leaves are sweet and eagerly devoured by livestock.

Mushrooms. The recent rains have resulted in numerous mushrooms appearing all over the Botanical Garden and in many suburban yards and we certainly saw a great variety of them today. I'm not adept at identifying mushrooms – I have to depend on Don and Bill for that information -- but I know a little about the basic lifestyle of mushrooms that is interesting. I thought I'd repeat some of these factoids from previous posts just because repetition is the secret of learning. To learn something you need to be exposed to it again and again. I hope this won't constitute over-exposure.

I've just listed all the mushrooms that Bill and Don identified at the bottom of this post. If you want to see what they looked like click on this link to Don's facebook album.

A mushroom is just a small part of a much larger organism. It's the equivalent of a flower, but, unlike the flowers on a plant, the rest of the mushroom is out of our sight. It's in the soil or inside the dead log or living tree. The part that is unseen is responsible for "feeding" the mushroom. It is busy gathering food so that it can grow and produce mushrooms. This unseen part is called a mycelium (pl.: mycelia) and it consists of a network of fine threads that spread throughout the substrate it is growing in. It functions like our digestive tract. The food we eat is broken down into simpler components inside our digestive tract. Our stomach and intestines secrete digestive enzymes that do this. Those simpler digestive products are then absorbed by our digestive tract and distributed to the rest of our body. Similarly, a mycelium secretes digestive enzymes into the area where it is growing. These enzymes break down the substances they come into contact with into simpler materials which are then absorbed by the mycelium. It's the same as digesting, only we call it "rotting." The other difference is that the material absorbed by our body is inside us (in the digestive tract) whereas it is outside the mycelium. A mycelium growing in a dead tree log is literally digesting (= rotting) the wood. A mycelium growing in the soil is digesting the organic material that makes up the soil.

Another comparison with flowering plants: the flower is a very tiny part of the entire plant. Think of all the roots, trunk, branches and twigs of a fruit tree and compare that to the flowers. The same is true of the relation between a mycelium and the mushroom. To give you an idea of how large a mycelium can get consider a honey mushroom found in Oregon. Researchers found that one mycelium covered an area of 3.7 square miles!

Sex and the single mushroom: A mycelium may live in the soil or dead wood or a living tree for a long time without producing a mushroom. For many fungi a sexual process is necessary in order for a mushroom can appear. Fungi can have multiple "genders", though not in the same sense as we do. The fungal gender is called a mating type. If two mycelia growing in the same substrate meet one another and they are of different mating types they will fuse. If they are of the same mating type they will ignore one another and continue on their separate ways. You might be thinking that the fusion of different mating types is like the union of sperm and egg in animals. In a way, it is, but with a difference. The fused mycelia continue to grow and the nuclei from each mating partner do not fuse, they mix together in a common cellular environment. So the fused mycelium now contains two types of genetic material that is intermingled but still separate. As this dual mycelium continues to grow the nuclei of each kind continue to increase in number, but remain separate. Only when external conditions are right will a mushroom be formed. When conditions are right the mycelium produces the mushroom and on the gills of the mushroom special cells are produced that contain one nucleus from each of the two mating types. In these cells the two nuclei fuse and then divided to produce spores. Each spore contains a mixture of the genetic material from each mating type. So the act of mating in fungi precedes the actual sexual process. Note that to produce a mushroom it is necessary for fusion of different mycelia (mating) to occur. How many mating types are there in fungi? In some kinds there are thousands of different mating types. This greatly increases the chances that a mycelium will meet another mycelium it can make a mushroom with.

Mycorrhizal mushrooms engage in a symbiotic (mutually beneficial)relationship with plants. The mushroom mycelium wraps around the plant roots and provides the plant with water and mineral nutrients. The plant, in turn, supplies the mycelium with sugars from photosynthesis and the building blocks of proteins. This is not a rare occurrence. It is estimated that 85% of all plant species participate in mycorrhizal symbiosis. If the host plant is deprived of making contact with its mycorrhizal partner it suffers terribly. Another aspect of the symbiotic relationship is seen when a mycorrhizal fungus estblishes connections to different trees. It can then act as a conduit, transferring sugars from one tree to another, even if they are different species. The implications of this for our understanding of forest ecology are just now being explored.

Two commonly encountered kinds are the Amanitas and the Russulas. Many of the Amanitas are poisonous. The Russulas have brittle flesh that is easily broken.

Wood rotting mushrooms: Not all the mushrooms that we see in the woods are mycorrhizal. If you see one growing on a living tree or a fallen log it is a wood rotting mushroom. People long ago noticed that some wood rotters left behind whitish wood fibers while others produced brownish wood fibers as a result of their activity. These gave rise to the names "white rot" and "brown rot," respectively. To understand the difference you need to know a little about wood. All plant cells are surrounded by a cell wall, made principally of cellulose. In tree cell walls there is another component that binds to the cellulose. It is called lignin and is very strong. It is the combination of cellulose plus lignin that permits trees to grow to their great heights. Pure cellulose is white. Pure lignin is brown. Because the two are so tightly bound to each other in wood it takes a lot of treatment to get rid of the lignin to make white paper. A lot of harsh chemical are involved and their action on wood pulp produces a noticeable odor. This make paper mills unpopular places to live near. But some fungi have solved the problem of digesting lignin – they are the white rot fungi. When they attack wood they digest the lignin, leaving the white colored cellulose behind. Some researchers think that white rot fungi could be employed by the paper industry to lessen the environmental impact of making paper. By now you've guessed what the brown rot fungi do – they digest the cellulose in the wood cell walls, leaving behind the brown lignin. Want an example of a white rot? The familiar Turkey tail mushroom that we see all over the dead wood in the garden is a white rot fungus.
Turkey tail mushroom, white rot mushroom

Lower surface, Cranefly Orchid
Upper surface, Cranefly Orchid

Cranefly orchid. The single leaf of the cranefly orchid is beginning to appear. This orchid has an unusual life history. Each fall, as the trees above shed their leaves, the corm of the cranefly orchid sends up a single leaf. After emerging from the soil the leaf leans over, flat against the forest floor, and persists throughout the winter. It appears that this plant is taking advantage of the open tree canopy during winter and using the sunlight to carry out photosynthesis. It is unusual for a temperate zone plant to rely on the weak winter sun for photosynthesis. Not only is there less energy available, but the cold winter temperatures make photosynthesis far less efficient than in summer. But in summer there is a lot more competition for light and the tree canopy is closed. The other puzzling feature is the maroon underside of the leaf. The green upper surface is obviously where photosynthesis takes place, but why is the undersurface purple?
The leaf will persist throughout winter and disappear by the end of spring. Then, around the middle of the summer, a flower stalk will emerge bearing numerous tiny, yellow-brown orchid flowers. No leaves appear at this time. The flower stalks are hard to find because their color is so similar to the surface of the forest floor – they just blend in with the background.

Beech Drops
Beechdrops. Looking to the right of the path we saw the morning sun illuminate hundreds of stems of Beechdrops, a parasitic plant. The plants are each about a foot tall and are brown because they completely lack chlorophyll. As the name implies, Beechdrops are found only in association with Beech trees. Their roots connect with those of the Beech and tap into the conducting vessels that carry water and nutrients to the tree as well as the photosynthetic products made by the Beech leaves. (There are other, non-photosynthetic, plants that parasitize the mycorrhizal partners of other trees. These get their water and nutrients indirectly from the tree, via the mycorrhizal fungus connected to its roots.

Spinyback orbweaver
Spiders: This is the time of year when we see (or run into) many of the large, circular spider webs, called "orb webs." The reason they appear late in the year is because most spiders are like annual plants. They die after laying their eggs. The eggs overwinter and the spiders that hatch out in the spring are really tiny. They can't build the large webs that stretch across the trails. As a result, they are barely noticeable and most people are unaware of their presence. Only later in the year, when they have reached their adult size do we run into their webs when we walk the trails in the garden. There are many different kinds of orbweavers and today we ran into two: the Triangulate orbweaver that has a prominent triangular mark on the top of its abdomen and the Spinybacked orbweaver that has a crab-shaped abdomen with multiple spines projecting from it.

Two kinds of hornbeams. At the junction of the Purple and Orange trail are two hornbeam trees growing almost side by side: an American hornbeam and a Hop hornbeam. This makes it easy to compare the trees. The most obvious difference is in the bark. The American hornbeam has smooth, gray bark and the trunk looks sinewy, as if there were muscles beneath the bark. The Hop hornbeam bark is brown and shredded, as if a cat had scratched it. Both trees have very dense, hard wood.

Banded tussock moth caterpillar
Caterpillar: Near the two hornbeams someone pointed out a fuzzy caterpillar, the larval stage of a moth called the Banded tussock moth. The caterpillar feeds on the leaves of a large number of different trees and will make a cocoon that incorporates the fuzzy bristles that decorate its body. (Just to clarify: insects that have complete metamorphosis, like butterflies and moths, go through four stages in their development: egg, larva, pupa, adult. In butterflies and moths the larval stage is called a caterpillar. In butterflies the pupa is naked and often decorated with colorful bumps or shaped like a dead leaf – it is called a chrysalis. The typical moth pupa is undecorated and dark brown in color. Before pupating the moth caterpillar surrounds itself with a silk covering that often incorporates leaves from its environment or the bristles and hairs from its own body. The pupa with its silken enclosure is called a cocoon.)

Is the river flooding or receding? Last year at this time I shared a bit of knowledge that I first learned in 1958. To determine if a river is flooding look for the location of the debris floating on its surface. If it is mostly in the center, then the water level is rising. If the floating debris is toward the edges, the flood waters are receding. This is useful information in an area subject to flash flooding.

Beaver marsh: I've been in Athens since 1978 and watched the changes in this Beaver marsh for over 30 years. Early on it was almost indistinguishable from the surrounding forest except for the beaver dam and the pond that resulted. The original beaver dam was located at the same place where the current cement block dam now stands. Gradually the trees began to die, unable to tolerate the continuous water submersion. The shrubs and subcanopy trees were cut down by the beaver and the whole area took on an open aspect as woody vegetation was removed or died. About 20 years ago the largest trees began to be utilized by Red-headed woodpeckers. The standing trees had been dead for some time and were colonized by wood-rotting fungus, making it easy for the woodpeckers to excavate cavities for their nests. About this time the beaver dam was destroyed by a flood and replaced by the cement blocks. (The reason the dam was replaced was to retain water. The University had a pig farm on S. Milledge Ave. that was in the watershed of the creek that fed the beaver pond. Retaining that water allowed the vegetation growing in the pond to remove many of the nutrients from the runoff and improve the quality of the water entering the Middle Oconee River. By this time the decay process was well advanced and the large trees that served as woodpecker nest sites began to fall. At present you can still see a few
Duck potato
"staubs," the heartwood remnants of a few of the trees that once covered the area. The area is now less a pond and more of a marsh, dominated by Duck potato, a marsh or shallow water plant that grows in standing water. Eventually, as silt accumulates, it will revert to forest again. Keep coming back and follow the progress of its change.

Ferns: We were running out of time so we hurried up the Orange trail and just stopped at the Scout bridge to see some Sensitive fern. At least one of them had a fertile frond, exclusively devoted to spore-producing structures. The much more obvious green, leafy fronds are sterile and never produce spores. Along the way we found Southern grape ferns, that also have separate fertile and sterile fronds and, on a fallen branch, an Old Man's Beard lichen.
Old man's beard liche

By now we were running very late so we returned to the Conservatory via the Flower garden and enjoyed the usual conversation and beverages at Donderos'.

Common Name
Scientific Name
Paw Paw tree
Asimina triloba
Chinese tea plant
Camellia sinensis
Southern red oak
Quercus falcata
Ostrya virginiana
Partridge berry
Mitchella repens
Horse sugar
Symplocos tinctoria
Cranefly orchid
Tipularia discolor
Beech drops
Epifagus americana
Triangulate orbweaver
Verrucosa arenata
Banded Tussock Moth Caterpillar
Halysidota tessellaris
Bignonia capreolata
Carpinus caroliniana
Silverbell tree
Halesia sp.
Spinybacked orbweaver
Gasteracantha cancriformis
Trumpet vine
Campis radicans
River birch
Betula nigra
Poison ivy
Toxicodendron radicans
Persicaria virginiana
Duck potato
Sagitaria latifolia
Southern grape fern
Botrychium biternatum
Sensitive fern
Onoclea sensibilis
Old man’s beard lichen
Usnea strigosa
Hornbeam disc
Aleurodiscus oakesii
Amanita sp.
Cantharellus cibarius
Turkey tail
Trametes versicolor
Entoloma sp.
False turkey tail
Stereum ostrea
Thin-maze flat polypore
Daedaleopsis confragosa
Multi-color gilled polypore
Lenzites betulina
Mustard yellow polypore
Phelinus gilvus
Armillaria melea
Bitter oyster
Pinellus stipticus
Purple Laccaria
Laccaria ochropurpurea
Clitocybe nuda
Hygrophorus sp.
Pear-shaped puff ball
Lycoperdon pyriforme
Fairy inkcap
Coprinellus disseminatus

[/end Don's Bullet list]