Friday, November 11, 2016

Ramble Report November 10 2016




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:
Visit this page to see the current Announcements.
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.

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


No comments:

Post a Comment

Post a comment