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.
Notes:
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.
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| 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.
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| Chinese tea plant blossom |
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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.
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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.
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| Turkey tail mushroom, white rot mushroom |
|
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| Lower surface, Cranefly Orchid |
|
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| Upper surface, Cranefly Orchid |
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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.
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| Beech Drops |
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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.
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| Spinyback orbweaver |
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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.
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| Banded tussock moth caterpillar |
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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
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| 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.
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| Old man's beard liche |
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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'.
SUMMARY OF OBSERVED SPECIES:
Common Name
|
Scientific Name
|
Paw Paw tree
|
Asimina triloba
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Chinese tea plant
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Camellia sinensis
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Southern red oak
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Quercus falcata
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Hophornbeam
|
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
|
Crossvine
|
Bignonia capreolata
|
Musclewood
|
Carpinus caroliniana
|
Silverbell tree
|
Halesia sp.
|
Spinybacked orbweaver
|
Gasteracantha cancriformis
|
Trumpet vine
|
Campis radicans
|
River birch
|
Betula nigra
|
Poison ivy
|
Toxicodendron radicans
|
Jumpseed
|
Persicaria virginiana
|
Duck potato
|
Sagitaria latifolia
|
Southern grape fern
|
Botrychium biternatum
|
Sensitive fern
|
Onoclea sensibilis
|
Old man’s beard lichen
|
Usnea strigosa
|
Mushrooms
|
Hornbeam disc
|
Aleurodiscus oakesii
|
Amanita
|
Amanita sp.
|
Chanterelles
|
Cantharellus cibarius
|
Turkey tail
|
Trametes versicolor
|
Entoloma
|
Entoloma sp.
|
False turkey tail
|
Stereum ostrea
|
Thin-maze flat polypore
|
Daedaleopsis confragosa
|
Multi-color gilled polypore
|
Lenzites betulina
|
Mustard yellow polypore
|
Phelinus gilvus
|
Honey
|
Armillaria melea
|
Bitter oyster
|
Pinellus stipticus
|
Purple Laccaria
|
Laccaria ochropurpurea
|
Blewit
|
Clitocybe nuda
|
Hygrophorus
|
Hygrophorus sp.
|
Pear-shaped puff ball
|
Lycoperdon pyriforme
|
Fairy inkcap
|
Coprinellus disseminatus
|
[/end Don's Bullet list]
