Today's Ramble was lead by Linda Chafin.
Here's the link to
Don's Facebook album for today's Ramble. (All the photos in this post are compliments
of Don.)
Today's post was written by Dale Hoyt and Don Hunter.
Attendees: 36 (a
new record)
Announcements:
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Today's reading:Linda read a poem by Wendell Berry:
The
Peace of Wild Things
When despair for the world grows in me
and I wake in the night at the least sound
in fear of what my life and my children's lives may be,
I go and lie down where the wood drake
rests in his beauty on the water, and the great heron feeds.
I come into the peace of wild things
who do not tax their lives with forethought
of grief. I come into the presence of still water.
And I feel above me the day-blind stars
waiting with their light. For a time
I rest in the grace of the world, and am free.
Kathy read a poem by Mary Oliver:
The Buddha’s Last
Instruction
“Make of yourself a light,”
said the Buddha,
before he died.
I think of this every morning
as the east begins
to tear off its many clouds
of darkness, to send up the first
signal — a white fan
streaked with pink and violet,
even green.
An old man, he lay down
between two sala trees,
and he might have said anything,
knowing it was his final hour.
The light burns upward,
it thickens and settles over the fields.
Around him, the villagers gathered
and stretched forward to listen.
Even before the sun itself
hangs, disattached, in the blue air,
I am touched everywhere
by its ocean of yellow waves.
No doubt he thought of everything
that had happened in his difficult life.
And then I feel the sun itself
as it blazes over the hills,
like a million flowers on fire —
clearly I’m not needed,
yet I feel myself turning
into something of inexplicable value.
Slowly, beneath the branches,
he raised his head.
He looked into the faces of that frightened crowd.
said the Buddha,
before he died.
I think of this every morning
as the east begins
to tear off its many clouds
of darkness, to send up the first
signal — a white fan
streaked with pink and violet,
even green.
An old man, he lay down
between two sala trees,
and he might have said anything,
knowing it was his final hour.
The light burns upward,
it thickens and settles over the fields.
Around him, the villagers gathered
and stretched forward to listen.
Even before the sun itself
hangs, disattached, in the blue air,
I am touched everywhere
by its ocean of yellow waves.
No doubt he thought of everything
that had happened in his difficult life.
And then I feel the sun itself
as it blazes over the hills,
like a million flowers on fire —
clearly I’m not needed,
yet I feel myself turning
into something of inexplicable value.
Slowly, beneath the branches,
he raised his head.
He looked into the faces of that frightened crowd.
Today's
route: Leaving the arbor, we made our way down the cement walk in the Shade
Garden and and then to the power line right-of-way via the mulched White Trail
Spur. From there we walked down to the river and turned left on the Orange
Trail, walking along the river to the Orange Trail spur which we took back to
the parking lot. We wrapped it up with coffee, pumpkin spice bars and fine
conversation in the conservatory.
 |
| Contour pile |
Contour piles
On the way down the White Spur trail we saw a long pile
of tree limbs and twigs running parallel to the trail for many feet. This is a
"contour pile," constructed by the Garden, and it follows the contour
of the hill. It is meant to reduce down slope erosion by retarding surface
runoff as well as providing some wildlife habitat. (Assuming it is ever going
to rain again.) Gary pointed out that he has heard them referred to as wren
piles because Carolina wrens, in particular, like to utilize the piles for
cover and nesting.
 | |
| Log with mushroom inocula |
Mushroom inoculation
is happening around the Garden trails. You will find stumps and logs standing
on end that are inoculated with plugs of mushroom spawn. (Spawn is a mixture of
sawdust and mushroom mycelium and spores). Don learned from Joey, the Shade
Garden curator, that to make a mushroom log the trunks of recently fallen trees
and their stumps are first cut into manageable sections. Then holes are drilled
into the wood and the mushroom spawn plugs hammered into the holes. They are
then sealed with wax to prevent colonization by unwanted species. Several
different mushroom species are being used, both edible and medicinal, to
inoculate the logs. It will be 9-15 months before the first mushrooms appear.
Most logs should produce several crops before they are exhausted.
 | |
| Red maple leaves; note teeth on lobes |
We have four species of Maples in the Botanical Garden: Box Elder, Red Maple, Chalk Maple
and Florida Maple (also known as Southern Sugar Maple). The first, Box Elder,
is easily identified because it has compound leaves, generally with 3 leaflets,
but sometimes with five or even seven leaflets. Red maple in our area is
3-lobed and the lobes have toothed margins. The other two maples, Chalk and
Florida have leaves that resemble the true Sugar Maple (the maple on the flag
of Canada) in having 5 lobes with smooth margins. Chalk maple leaves are
fuzzier underneath and Florida maple leaves are lighter colored beneath. Linda mentioned
that Red maple leaves vary in shape geographically – those on the coastal plain
have hardly any lobes. It is difficult to imagine why such differences in leaf
shape occur. If they are adaptive we don't know why or how. It is also possible
that such differences adaptively neutral, making no difference in the plants
survival or success.
Garden Art? Several
of us commented on the “art installations”, comprised of limbs, that are
becoming more prevalent along some of the trails. Most of us think they are not
a welcome addition to the trail experience at the Garden.
 | |
| White oak leaf (L); Northern red oak leaf (R) |
 |
| Shade leaf of Northern red oak (compare with photo above) (also infected with Tubakia leaf spot fungus) |
Shade leaves, Red and White oak groups. We
stopped to observe a large shade leaf from a northern red oak and talked about
the differences between the shade leaves, found lower on the tree where
sunlight is limited, and the much smaller sun leaves, found in the upper
canopy. The difference between leaves on the same tree growing in full sun
versus shade has been discussed several times on previous rambles, most
recently here.
Last
week's post also discussed the differences between trees of the red oak
group of species and the white oak species group.
Leaf spot disease.
The large red oak leaf and many others on the ground are covered with many
black spots, caused by a fungus called Tubakia Leaf Spot, a pathogen that
afflicts oaks; red oaks seem to be most susceptible. It is considered a cosmetic
disease and only rarely becomes a problem. For more information consult this website.
Mast. Sue wondered
if this is a “mast” year for the acorn crop. Mast is a general term applied to
the nut crops of forest trees, such as beech, oak, hickory, chestnut etc., and originally
refers to those eaten by pigs. It is Old English in origin and not related to
the term masticate which comes from the Latin, according to the Oxford English
dictionary. Some years the mast, or crop, is much more abundant than in other
years. This in itself is not surprising – you would expect a tree that expended
a lot of effort producing nuts one year would have to build up its reserves for
one or more seasons before producing another large crop. What is surprising is
that in some species big mast years tend to be synchronized over a very large
area. The ecological consequence of simultaneously producing a large number of
nuts is that seed predators (the animals that eat the nut crop) may be
overwhelmed. If nuts are super-abundant the nut eaters may not be able to consume
all of them. This would leave more nuts to survive and germinate than if all
the trees produced the same middling size crop each year. Then the numbers of
seed predators could eventually increase to match the size of the crop and all
the nuts would be consumed. So synchronous high mast years seems to be
adaptive, but how the synchrony is achieved is at present unknown.
Tanning. The
word "tan" is derived from the ancient leather making process in
which animal skins were soaked in water with the ground up bark of oak trees.
This treatment prevented the skins from rotting and made them strong, supple
and waterproof. From such tanned hides many vital objects were made: shoes,
bridles, harnesses and clothing. It is inconceivable that people in northern
Europe could have survived winter without leather clothing or footware. No one knew
why tanning worked, they just knew that it did. (For a great read about the
historical importance of oak read Oak The
Frame of Civilization, by William Bryant Logan (W. W. Norton, 2005). It's a
fascinating read.)
The active ingredient of oak bark is a substance now know
as tannin. It is a bitter-tasting
substance that irreversibly binds to proteins. That property is why the oaks
produce it. Bark is not the only place tannins are found – they are also
produced in oak leaves and the acorns. Caterpillars that eat oak leaves ingest tannins
along with food. The tannins not only make some of the protein in the leaf
tissue unavailable, they also bind to the digestive enzymes in the gut that
would digest the food. As a result it takes a caterpillar longer to grow to
maturity the higher the tannin concentration. And the oaks can up the ante.
When an oak leaf is being eaten it sends a signal out to other leaves and even
those that are not being eaten will increase their tannin content. There is
even evidence that nearby trees can increase their tannin contents if a
neighboring tree is attacked by herbivores.
The last time we visited the power line ROW (right-of-way)
many of the plants were still blooming. Today all have set seed and we tried
identifying them from their non-floral features as well as looking at their
seeds. We found 5 plants in the aster family: tall thistle, giant ironweed and
three species of Verbesina,
(collectively called wingstems).
Wingstems (Verbesina). There are a multiplicity of
common names for each of the wingstems, so, at the risk of alienating everyone,
I'm going to use the scientific names. Here's a table of both names:
|
V.
alternifolia
|
Wing-Stem, Wingstem
|
|
V.
occidentalis
|
Yellow crownbeard, Crownbeard, Southern Crown-beard
|
|
V.
virginica
|
Frostweed, White crownbeard, Tickweed
|
 |
| Verbesina sp. with alternate leaves |
 |
| Verbesina occidentalis with opposite leaves |
 |
| Verbesina sp. seed head; wings can be seen on seeds |
The Verbesinas have narrow ridges of tissue running along
the length of their stems. Two have alternate leaves Wingstem (V. alternifolia)
has alternate leaves and stems, yellow crownbeard (V. occidentalis) has
opposite leaves and stems. Several of
the wingstems still retained seed heads full of seeds. Even the seeds of wingstem have wings. We saw a lone white crownbeard (frostweed)
which still retained a few white petals.
It has alternate leaves and stems and not bearing white petals, it looks
very much like wingstem. While looking at the white crownbeard we noticed a
large grasshopper on the plant.
 |
| Tall Thistle seed head |
 |
| Tall thistle leaves |
 |
| Tall thistle seeds with parachutes |
Tall thistle.
The seed heads on the tall thistle are still full, for the most part, and the
white color present on the underside of the leaf is an indication that this
thistle is a native species. Each seed has a tuft of many hairs, so it is wind
dispersed.
At the fence, we stopped to look at the Maryland (wild) senna, with many dark
seed pods still hanging on the plant. We
opened one of the pods to look at the seeds.
 | |
| Tall ironweed seeds with parachutes |
 | |
| Tall ironweed seed heads |
The seed heads of Tall
ironweed look like shaving brushes.
 |
| Differential grasshopper |
George found a sluggish Differential grasshopper clinging to some of the wingstem stems. I
thought it was too cold to move but it surprised me with an amazingly strong
leap to safety before it could be shown to the rest of the group. The key it its identity is the herring-bone pattern on its hind leg femur.
 | |
| A torpid Bumble bee clings to a Goldenrod inflorescence |
A lonely Bumble
bee clung, immobilized by the cool weather, to one of the last Goldenrod
flower heads to be found in the ROW. Bumble bees are annual species. Colonies
are started by inseminated queens who have overwintered. The queens first task
is to raise a group of workers who will forage for pollen and nectar to feed
her growing colony. Later in the year she and her helpers will start to produce
future queens and, finally, males. At that time the future queens from all the
colonies in the area engage in mating flights. The newly inseminated queens
search for places where they can hibernate through the coming winter and the
colony falls apart. The old queen dies and her workers and males wander about,
feeding on the few nectar sources that are available until they, too, expire.
 | |
| Gulf Fritillary caterpillar on passionflower leaf |
Purple passionflower
vines are covered with many senescing leaves, but a few are still green and
many green fruits still on the vine. (The fruits turn yellow and wither as they
ripen.) Don sampled the seed and pulp contained in the fruit. It was very sour
at first taste but as you got closer to the seed, the sweetness was present. George
found a Gulf fritillary caterpillar on one of the still-green leaves. The Gulf
fritillary is a migrant from the coastal plain and peninsular Florida. Butterflies
make there way to our area by the end of spring/beginning of summer. As long as
the weather remains warm and passion flower vines are in good condition the
butterflies can complete their life cycle here. But caterpillars that are still
feeding as the leaves senesce are doomed to failure. Even if they can pupate
the chrysalis cannot remain viable during our winters. But don't despair; we will
get resupplied next summer by a new influx of migrants from Florida.
 | |
| Lurid sedge seed |
 | |
| Lurid sedge |
Next to the passionflower vines we saw a variety of
sedges, grasses and rushes in an area that is normally very wet during winter
and spring. We saw Lurid sedge, with
spiked seed heads. It had the sedge-characteristic stems that are triangular in
cross section. A cross-section of the leaves are in the shape of an “M” (or
“W”, depending on how you look at it).
We opened up one of the seed heads and found many small seeds inside. Each seed encased in a sac the shape of a
tear drop. The seeds in most sedge species are three-sided.
 | |
| Eastern wild rye |
The grass was Eastern
wild rye.
 | |
| River cane; note bristles at base of leaf blade & sheath junction |
River cane. Near
the river are a few plants of our native bamboo, River cane, the cane of
canebrake rattlers. There used to be huge stands in many bottom lands. (There
are two species of cane in our area, River
cane and Switch cane, but they
are difficult to tell apart.) Linda pointed out the bristles on the stems where
each leaf sheath was attached. You rarely see river cane flowering. It may take
100 years. At present the largest stands are really genetically a single plant –
most of the individuals are clones of a single original, founding plant. After
waiting so long to flower, once a stand of river cane flowers, all of the
plants die die after shedding their seeds. Linda mentioned that in her entire career, she
has seen river cane in flower only two times. River cane is hard to propagate
and is not typically an invasive plant. Ted mentioned that Thomas Peters (the
person who removed the masses of Chinese privet from the Orange trail) is
collecting seeds from cane stands that are in flower in order to propagate
river cane at different locations, one of them being the original Chinese
privet patch that was eradicated here at the Garden. We had a discussion on how
a stand may be replenished once it dies. It is difficult for this to happen
with seeds from the plants. Because the stand is genetically one plant, approximately
90 percent of the seeds that drop are not viable. Reproduction from seeds is
likely to occur only when there is cross-pollination between one stand and
another nearby stand and those conditions are exceedingly rare today.
Gary said Thomas Peters is partnering with the Audubon
Society on a river cane restoration program. He will be selling the plants to
the society for replanting for $15 per plant.
Canebrakes provide a habitat for Bachman's warbler and three
species of Pearly eye butterflies.
Why a stand of
River Cane produces so much inviable seed.
River Cane is long lived, reproducing primarily by
underground rhizomes. Since it may be 70-100 years before they flower, set seed
and die, they have a lot of time to form huge clones of genetically identical
stems, all descendents of one original lucky seed. Before colonization by
Europeans the Cane formed extensive, continuous populations on flood plains and
river banks. These were called cane brakes and were impenetrable. In
pre-settlement times these canebrakes were likely more genetically diverse than
the small, pitiful remnants we find today. The early colonists cleared the
canebrakes for their farms, reducing their extent and, consequently, their
genetic diversity. The diversity decreased because a small sample from a large
population cannot capture the full diversity of the population. Imagine a huge
container filled with M&Ms of every conceivable color. Reach in a take out
a handful and throw the rest away. You handful probably has some of the most
common color but can't reflect the variety that existed in the original
container. This is the situation River cane found itself in after the onslaught
of the colonists: formerly huge, contiguous populations of cane reduced to a
few, scattered remnants. Those remnants could increase in size by vegetative
reproduction. The survivors sent out rhizomes that sprouted new stems and over
the years, if undisturbed, the patch could increase tremendously in number of
stems. But the stems would not have increased at all in genetic diversity. When
they flowered all the pollen was from their same group of genetically identical
stems. Even though pollen from one stem was fertilizing an ovule on another
stem they were self-fertilizing.
Why inviable seed results
from self-fertilization.
Typical plants and animals have two sets of chromosomes
in each of their cells, one set inherited from their male parent and one from
their female parent. Each set of chromosomes consists of thousands of different
genes (in humans the number is approximately 20,000; in plants there are more).
Some of those genes in each set will be mutant, differing from the normal gene,
but the majority will be normal. Since each cell has two copies of each gene if
one copy is normal the cells function will usually be normal, even if the other
gene copy is mutant. (In this case the mutant form is said to be recessive to
the normal gene.) When both copies of the gene are mutant then the appearance
of the organism differs from the "normal." This difference may be
trivial, like the color of the eyes or it may be very severe; e.g., causing the
death in an early embryonic stage. Such mutant genes are called
"lethal;" if they are recessive they are called "recessive
lethals." In humans it has been estimated that everyone carries, on
average, a single copy of approximately 15 different deleterious mutant genes.
The only time a problem will arise is when your spouse and you carry the same mutant
gene. In that case you each have one good copy and one mutant copy of the same
gene. From the rules discovered by Gregor Mendel we know that your children will
a have 25% chance of inheriting the mutant copy from both parents. If they do
inherit two mutant copies they will show the mutant feature. This could be like
a couple who both have brown eyes getting a blue eyed child. Or it could be
like a couple who are both normal giving birth to a child suffering from cystic
fibrosis. Or a normal couple could suffer a miscarriage early in pregnancy due
to the fetus having two copies of recessive lethal mutant gene. But the chances
of this happening are 25% only if the two parents carry the mutant form of the same gene. If one parent has 15
deleterious mutant genes, but none of them are the same as are carried by the
other parent, then their children are expected to be normal. The chances of two
unrelated people drawn at random having the same bad genes are pretty small.
Now, back to the River cane. The few remaining cane
stands are pretty much composed of clones of the same individual plant. Every
stem in the population is genetically identical to every other stem. When they
develop flowers it is like mating with themselves (self fertilizing). So let's
look at what effect the number of recessive lethal genes would have on the
viability of the cane seed. If the cane plants only have 1 recessive lethal,
then 25% of their seeds will be inviable but 75% will be viable. Not too bad.
If they have 2 different recessive lethal genes then the percentage of viable
seeds drops to 56%. With 3 recessive lethals only 42% of the seeds will be
viable; with 4, 32%; with 5, 24%. If we continue calculating with just 10
recessive lethals only 6% of the seeds will be viable.
The future looks gloomy for the River cane to reproduce
by seed, unless the genetic variation of the cane stands can be increased by
mixing together cane from different stands.
Miscellaneous
plants on the Orange trail.
 | |
| River oats |
River oats love the sandy levees along the banks of
rivers and creeks.
 | |
| Broomsedge seeds |
Broomsedge is not a sedge, it's a grass. It was used to
make brooms. Several Ramblers remember their grandmothers and mothers making
brooms with it.
 | |
| Camphorweed |
Earlier this year we found a really malodorous weed Camphorweed
growing in this section of the Orange trail. Today we saw many rounded dried seed
heads and discovered that they smell of camphor, just not as strongly as when
flowers were present.
 | |
| Fragrant sedge |
The river is way down, probably as low as many of us have
seen in recent years.
SUMMARY
OF OBSERVED SPECIES:
|
Red maple
|
Acer
rubrum
|
|
Northern red oak
|
Quercus
rubra
|
|
Tubakia Leaf Spot
|
Tubakia
sp.
|
|
White oak
|
Quercus
alba
|
|
Tall thistle
|
Cirsium
altissimum
|
|
Wingstem
|
Verbesina
alternifolia
|
|
Yellow crownbeard
|
Verbesina
occidentalis
|
|
White crownbeard
|
Verbesina
virginica
|
|
Maryland (Wild) senna
|
Senna
marilandica
|
|
Tall ironweed
|
Vernonia
gigantea
|
|
Bumblebee
|
Bombus
sp.
|
|
Differential grasshopper
|
Melanplus
differentialis
|
|
Purple passionflower
|
Passiflora
incarnata
|
|
Gulf fritillary
|
Agraulis
vanillae
|
|
Lurid sedge
|
Carex
lurida
|
|
Eastern
wild rye
|
Elymus ??
|
|
Rush
|
??
|
|
Giant cane/
Switch cane |
Arundinaria
gigantea
A. tecta |
|
River oats
|
Chasmanthium
latifolium
|
|
Broomsedge
|
Andropogon
virginicus
|
|
Camphorweed
|
Pluchea
camphorata
|
|
Fragrant sedge
|
Carex
odoratus
|
