Eighteen ramblers met today on what
started as a foggy morning but the fog soon burned off. Our decision to start the
rambles earlier this summer seemed to be the right one. The day didn't start heating
up until we had finished our walk.
Don Hunter's facebook album of
the ramble can be viewed here.
At the side of the parking lot several people noticed a hawk sitting in a nearby
tree. It is possible that
this is the same hawk we have previously seen in the power line. It seemed
unperturbed by the cluster of people staring at it. The group moved off to
begin the ramble and the Hawk followed them, flying to another nearby tree. It
is unknown which of us smelled like a small rodent. I've included Don's photo
of the hawk in the hope that one of our bird-knowledgeable ramblers can confirm
its identity (Red-tailed or Red-shouldered). Another thing to notice is that it
appears to have only one leg. Let us know if you think the bird is simply
resting on one leg with the other tucked out of sight.
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| One-legged hawk? |
UPDATE!!
Information from Chuck Murphy indicates that the hawk is an immature Red-tailed Hawk. Chuck further provided two photos of the same individual, taken by Heather Lickliter. They clear up the mystery of the missing leg:
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| There it is! |
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| Missing the left leg? |
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| Now you see it! |
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| Now you don't! |
I've posted a possible explanation for the one legged behavior. Click here to read it.
The reading was provided by Silvio Curtis and is from the Ursula K. Le Guin book Always Coming Home, pp. 51-52, and can be found here.
Our route today was through the International Garden, taking the walkway on the left side (closest to the conservatory), and then through the hop vine arbor, past the Paw Paws to the Orange Trail connector; then down the connector and over the bridge to the Orange Trail. Then left on the Orange Trail to return via the upper parking lots.
Before departing the Arbor I
passed out an 8-page minibook with drawings of seven common ferns that can be
seen on the Orange Trail. There were not enough copies to go around so people
shared.
In the patch of native plants growing by the International
Garden entrance there were only two species still blooming, the Virginia
Spiderwort and Stoke's Aster, the latter looking a little bedraggled from last
night's heavy thunderstorm. The Blue false indigo bushes have swollen bean
pods.
In the Garden proper we stopped
near the Zinnias to talk about one of my pet peeves. Plant breeders
"improve" plants like Zinnias by breeding for larger flowers with
more petals. Zinnias are composites, which means that what most people call the
zinnia flower is really a compact group of small florets, similar to a daisy.
Originally only the outermost ring of florets had the broad, brightly colored petals
(these are called ray florets) and
the remaining florets (the disk
florets) lacked a prominent petal. But those disk florets produced the nectar
that was why the butterflies visited the Zinnias. In fact, many people planted
zinnias in their garden because they attracted butterflies. The effect of the
breeders efforts was to create a plant in which many of the disk florets were
replaced by ray florets. This made the flower head larger and showier, but did
so at the expense of nectar production. Such flowers are not as attractive to
butterflies or other nectar-loving insects, like bees. So, as it so often
happens, form is valued over function. The modern zinnia will still attract
butterflies, but not like the old-fashioned varieties. So if you plant Zinnias
because you want butterflies to visit your garden you would be better off to
seek out the old style of zinnia, one without all the increased petals.
We also noted several kinds of
Yucca at this point in the garden. Many different yucca species are called
Spanish Bayonet. The real Spanish Bayonet can be found growing in Big Bend
National Park in Texas. There are large stands of them there and they are tall,
from 8 to 10 feet in height, exclusive of the flowering stalk, which can add
another 10 feet and 150 pounds to the plant.
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| Fruit of Hop vine |
Then it was on to the Hop arbor
where the Hop vines are growing. I pointed out the Hop fruits that are used to
flavor beer and are also similar in appearance to the fruits of the Hop hornbeam
tree. 2012 was the last year that the Hop hornbeams in the Garden produced a
lot of fruits, so search your memory for what they look like.
Further along the walkway we
pass a group of Paw Paws. These are moderately tall trees, but only two fruits
were seen.
Just beyond the Paw Paws there
was a strand of spider silk stretched across the walkway just above our heads.
A tiny spider was traversing it and the question arose: how did the spider get
the silk across the sidewalk that high up? You might have noticed that when you
go outdoors early in the morning that you often feel strands of silk brushing
against your bare arms. These are from "ballooning" spiders. Tiny
spiders climb to an elevated position, tip their abdomen up and release a
strand of silk from their silk glands. The silk thread is so light that a
gentle breeze can catch it and carry it away. If it comes in contact with
another surface it will stick and the spider can use that line as a walkway to
start a web or simply cross an open area.
In the "Physic" garden
are plants that were used for medicinal purposes. This garden is planted with
the varieties that a well know local physician, Dr. Lindsey Durham, who lived
in Scull Shoals, GA, had in his own garden. Growing here are: Colic root,
Weeping redbud, Rattlesnake master, Beebalm, Feverfew, Wild quinine, and Common
mullein. Scull Shoals is now a ghost town in the Oconee National Forest. To
learn more about this important community in Georgia history and more about Dr.
Durham, click here.
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| Hugh and Franklinia |
Growing in a large pot is a
specimen of Franklinia, the plant
first discovered by John and William Bartram on the Altamaha River near Darien,
Georgia, in 1765. It was later described as a new species by William Bartram
and last seen in the wild in the early 1800s. It now survives only in
cultivation.
Nearby is a small house filled
with paper tubes about a foot long and 1/4 inch
in diameter. This is a
"house" for solitary bees. Unlike honey bees solitary bees do not
live in hives composed of thousands of other bees with division of labor among
them. Solitary bees are not social. Each fertilized female constructs her own
"nest" and provisions it with food for her young. There are many
different kinds of solitary bees but many of them construct nests in the same
manner. They excavate a tunnel in the ground or in the end of a twig or broken
stem. She then gathers pollen and nectar to place in the bottom of the tunnel,
lays an egg on the mixture and then seals the chamber off using some
environmental material like mud or cut off pieces of leaves or chewed up plant
fibers. If the tunnel is long enough she will continue making and provisioning
chambers until the tunnel if filled with her future offspring. Then she dies.
Inside the chambers the eggs hatch and the grub-like larva feeds on the
pollen-nectar mixture until it grows large enough to pupate. The pupae overwinter
and the following spring the adult bees emerge from their chambers, mate and
repeat the process.
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| A "house" for solitary bees |
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| Capped tubes filled with bee larvae |
Some of the paper tubes in the
picture to the left have already been filled with bee larvae and capped with
Georgia red clay. An interesting detail is the way sexes are determined in Hymenopterans
(ants, bees, wasps and their relatives). Other tubes appear to be capped with plant fibers -- this may be a different species using the tubes. The female controls the sex of her
offspring. She stores sperm from her mating and uses it when she wants to. If
an egg is fertilized it develops into a female. (In a honey bee colony it will
develop into a sterile worker bee.) An unfertilized egg develops into a male.
In most hymenopterans the males only role is to mate with a female. When a solitary
provisions a lot of cells in a long tunnel she holds back sperm when producing
the eggs for the last few cells so they will develop into males. Since these
cells are closest to the end of the tube the males emerge first. The last bees
to emerge are the females produced from the earlier, fertilized eggs laid in
the back of the tube. They are met by a crowd of males flying around the tube
opening, eager to mate.
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| Wasp seeking bee larvae? Yum, yum!! |
All is not safe in a capped tube though, as the photo to the left shows. A wasp has discovered an uncapped cell (or uncapped it) to get some tasty bee larvae to feed to its offspring.
Solitary bees are vital parts of
the ecosystem. They are often more efficient at pollination than honey bees and
more effective. In an apple orchard pollinated by a few dozen solitary bees can
produce more apples of higher quality one hive of thousands of honey bees. In
addition, many native plants that are ignored by honey bees are reliant on
solitary bees for their pollination services. Modern industrial agricultural
practices destroy the habitat necessary to support solitary bees, greatly
risking their extinction and that of the native plants that depend on them.
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| American Wisteria |
Growing on the bridge is a
native species of wisteria, American Wisteria, which is still in bloom. This species
is not invasive, unlike the Chinese Wisteria that can quickly escape from
cultivation and spread to adjoining tree.
Hugh also pointed out a Virginia
Creeper vine and pointed out that its 5 leaflets clearly distinguish it from
Poison Ivy, which has only 3 leaflets. Many people confuse the two. Virginia
Creeper is an "aggressive" plant, meaning that it easily will spread
out of its desired place in the garden and shade out other plants. But it is
not invasive. Invasive plants are aggressive but not all aggressive plants are
invasive.
We also encountered a planting
of a Beautyberry cultivar that was loaded with blossoms. If each of these sets
fruit the shrub will be laden with beautiful purple berries in the fall. A couple of Butterfly Peas were
also seen growing by the sidewalk.
The pieces of wood that border the sidewalk near the
meditating woman statue are being rotted by a Turkey Tail-like mushroom. It has
pores on the lower surface from which the spores are released. The pores are
found on true Turkey Tail mushrooms, as well are other fan-like wood rotters.
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| Jack in the pulpit fruits |
Nearby Hugh spotted a Jack-in-the-pulpit with developing
fruits. They are presently green but will turn a brilliant crimson by fall.
We stopped to examine the new growth of a Sourwood. At this time
of year the new growth of trees is usually still green in color and you can see
how much they have elongated in the 1-2 months since the buds have opened. The
rate of growth is surprising because it is seldom noticed by most people.
We found our first fern which turned out to be a Christmas
fern that had not yet developed fertile fronds. This was the first of many
Christmas ferns that were to be seen along the Orange connector and the Orange
Trail itself.
Nearby was a Rattlesnake fern. We could be confidant of our
identification because it had the fertile frond emerging from the stipe at the
level of the fronds. The other similar fern, Grape fern, does not develop its
fertile frond until later in summer.
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| Rattlesnake fern with fertile frond in center |
On the Orange Trail:
A general question:
We found very few plants in flower today, a sharp contrast
to the early spring when all the spring ephemerals were blooming. The
explanation usually given is that when the trees leaf out there is not enough
sunlight reaching the ground to permit the development of seeds, so flowering
plants are few and far between. But why, then are ferns so abundant? Is it
because ferns do not produce seeds? They may produce only spores, but they
produce massive quantities of them. I don't know how much energy a fern diverts
into spore production, so I can't answer that question, but it has been
bothering me for some time. Perhaps you can come up with some ideas. If you do,
put them in the comment box at the bottom of this post.
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| A group of Broad beech ferns |
Ferns seen: Christmas Fern, Ebony spleenwort, Broad beech fern, either
Rattlesnake fern or Dissected Grape fern, Lady fern. The Rattlesnake and
Dissected Grape ferns appear very similar to one another. If there is no
fertile frond present I can't tell the difference. So those we saw are either
Rattlesnake ferns that have not yet produced a fertile frond or Dissected Grape
ferns that will develop their fertile fronds later in the summer.
The only wildflower we noticed on the Orange trail was White
Avens; a flowering shrub, Elderberry, was also seen. Other plants noted were Catbrier,
Trumpet vine, Wild Yam and Bedstraw (also called Cleavers or Catchweed because
its bristles cause it to cling to the fur and clothing of passing mammals. It's
called Bedstraw because it was used to stuff mattresses by early pioneers.
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| Beech blight aphids in close up |
One of more entertaining sightings was the cluster of Beech
blight aphids found on a lower branch of an American beech tree. These insects
suck the juices from the Beech twigs and reproduce very rapidly, producing a
very large colony of aphids. Each one secretes a waxy substance that covers
much of its body and makes the group look like little tufts of cotton glued to
the twig. When disturbed by shaking the branch they immediately started to
boogie-woogie, much to our entertainment. You can find more information and a
short video of the dance here.
Mushroom sex:
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| The spore-producing surface of Split gill mushroom the gills split toward the edge of fruiting body |
On one of the rotting logs we saw some Split gill mushrooms.
I made the casual remark that this fungus has thousands of different sexes.
That immediately tweaked the curiosity of a number of ramblers who deluged me
with questions. I'll try to answer these and, if you're not interested in
mushroom sex, you can skip the rest of this post.
I've tried to explain this material without making a lot of
assumptions about your previous knowledge. A more technical description of sex
in Split gill fungi can be found here on the web.
First, though, you need to know (or remember) that mushrooms
are the fungal equivalent of flowers. Just as a flower is produced by a plant,
a mushroom is produced by a fungus. In flowering plants the body (roots, stems,
leaves) of the plant provides the nutrients to produce the flowers and,
ultimately, the seeds. In a mushroom-producing fungus the part corresponding
the roots, stems and leaves is the mycelium. It looks very different from a
plant. You've seen a mycelium before. When bread gets moldy the fine, white
threads you see surrounding the colored molds are the mycelium of the mold.
Similarly the wood-rotting mushrooms have fine threads the penetrate everywhere
in the wood, secreting digestive juices that break down the wood fibers and
then absorbing those digestive products. To produce a mushroom the mycelium
must acquire enough energy from its log (or whatever it is rotting). But that
is not enough. It has to meet and fuse with a mycelium of the same species but
a different sex.
So most mushrooms are the result of a sexual act. But mushrooms
do it a lot differently than other organisms. There is nothing like easily recognizable
male and female fungi, and a fungus doesn't mate with just any other fungus. Fungal
sexes are separated into what are called "mating types." In order to
produce a fruiting body (a mushroom) the mycelium of one individual must fuse
with the mycelium of a different mating type. The mating types are not visibly
different. They can be determined in the laboratory by whether or not two
mycelia can fuse. If they can't, they are the same mating type. If they can,
they were different mating types and the fused portions will go on to produce a
fruiting body. A Harvard botanist, John Raper, discovered that there weren't
just two mating types in the Split gill fungus, but many different ones. He
further discovered how the mating type was genetically controlled and that the mating
type genes were highly variable. So a Split gill can mate with any other type
of Split gill except one that has the same mating type. With that knowledge he
estimated that, worldwide, there were 20,000 different mating types to be found
in Split gill fungi. One species, twenty thousand sexes!
Mushroom sex differs in other ways from that seen in plants
and animals. In plants and animals when egg and sperm come together their
nuclei fuse to produce a single cell. That cell has a single nucleus that
contains the chromosomes (and genes) of both parents. Fungi delay the nuclear
fusion. Instead, when two mycelia fuse their respective nuclei intermingle in a
common cytoplasm. (The fungal cytoplasm is not divided into cells like that of
a plant or animal. Instead it is a single cytoplasm within which the nuclei can
move about more or less freely. So after the two mating types have joined their
mycelia the fungal cytoplasm contains two genetically distinct nuclei. In other
words, mycelial fusion is not the same as egg and sperm fusion. It does not
result in a single cell with a single nucleus combining the genetic material of
both parents. It results in a cytoplasm in which two genetically distinct
nuclei coexist -- a special kind of "hybrid" called a dikaryon. (The di- means two;
-karyon is a Greek word that refers to the nucleus; thus, a dikaryon is an organism with two different nuclei in its cytoplasm.) The dikaryon mycelium can
continue to grow and when the conditions are right it will produce a mushroom.
Within the tissues of this mushroom are specialized cells, called basidia, that
will produce spores. Within each basidium the two genetically different nuclei
fuse and then undergo the same type of division that human egg or sperm precursor
cells do, called meiosis. This type of cell division reduces the amount of
genetic material by half in each resulting cell. The cells that result from
this type of division become spores and are released from the gills of the
mushroom by the billions, to drift away on the gentlest of breezes. Those few
that land in suitable places will germinate to form a new mycelium that
combines the genetic makeup of both parents, except it will have only one or
the other mating type. And so the cycle of life continues.
SUMMARY OF OBSERVED SPECIES:
Common Name
|
Scientific Name
|
Red-tailed Hawk
|
Buteo jamaicensis
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Virginia spiderwort
|
Tradescantia virginiana
|
Stoke’s aster
|
Stokesia laevis
|
Blue false indigo
|
Baptisia australis
|
Paw Paw
|
Asimina triloba
|
Yuccas
|
Yucca sp.
|
Hops
|
Humulus lupulus
|
Colic root
|
Aletris farinose
|
Weeping redbud
|
Cercis canadensis 'Covey'
|
Rattlesnake master
|
Eryngium yuccifolium
|
Beebalm
|
Monarda sp.
|
Feverfew
|
Tanacetum parthenium
|
Wild quinine
|
Parthenium integrifolium
|
Common mullein
|
Verbascum Thapsus
|
Franklinia
|
Franklinia alatamaha
|
Solitary bees
|
Hymenoptera
|
Butterfly Pea
|
Clitoria mariana
|
American wisteria
|
Wisteria frutescens
|
Virginia creeper
|
Parthenocissus quinquefolia
|
Beautyberry cultivar
|
Callicarpa sp.
|
Turkey Tail mushroom
|
Trametes versicolor
|
Jack-in-the-pulpit
|
Arisaema triphyllum
|
Sourwood
|
Oxydendrum arboretum
|
Redbud
|
Cercis canadensis
|
Christmas fern
|
Polystichum acrostichoides
|
Rattlesnake fern
|
Botrypus virginianus
|
Wild yam
|
Dioscorea villosa
|
Old Man’s Beard
|
Usnea strigosa
|
Bedstraw
|
Galium aparine
|
White Avens
|
Geum canadense
|
Elderberry
|
Sambucus canadensis
|
Broad beech fern
|
Phegopteris hexagonoptera
|
Lady fern
|
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Ebony Spleenwort
|
Asplenium platyneuron
|
Split gill mushroom
|
Schizophyllum commune
|
American Beech
|
Fagus grandifloria
|
Beech blight aphid
|
Grylloprociphilus imbricator
|
Catbrier
|
Smilax glauca
|
Trumpet vine
|
Campsis radicans
|
