Today's Ramble was led by Dale Hoyt.
The photos in this post were
contributed by Katherine Edison. Katherine also has a personal blog that you will enjoy.
Today's post was written by Dale Hoyt.
31 Ramblers met today.
Show &
Tell: Richard brought three items for identification:
1) an invasive species
of vine, Cinnamon Vine (Dioscorea
polystachya) of Yam;  | |
| Yellow Passionflower, leaf and tendril |
There was
much confusion about the passion vine. P.
lutea is not that same as the Purple Passionflower, P. incarnata. The leaves are shallowly lobed, the flower is yellow
and smaller, and the vine tends to be found in shady locations. Purple
Passionflower prefers sunny locations, has large, purple and white blossoms and
has leaves with more pointed lobes. In the Botanical Garden we have found
Yellow Passionflower growing along the White Trail near the river. It can also
serve as a host plant for the Gulf and Variegated Fritillary butterflies.
Today's reading: Rich
contributed a reading from Dostoyevsky’s The Brothers Karamazov:
Love all God’s creation, both the whole and every grain of sand. Love
every leaf, every ray of light. Love the animals, love the plants, love each
separate thing. If thou love each thing thou wilt perceive the mystery of God
in all; and when once thou perceive this, thou wilt thenceforward grow every
day to a fuller understanding of it: until thou come at last to love the whole
world with a love that will then be all-embracing and universal.
Today's route: We went through
the Visitor’s Center and across the bridge to the Meditation Garden and then
walked a short distance down hill and crossed the larger bridge to the Flower
Garden, where we wandered our way back through the Heritage Garden and back to
the Visitor’s Center.
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| Small's Ragwort |
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| Small's Ragwort, lower leaves |
We have previously seen two kinds of Ragworts in the
Garden. The first to bloom is the Golden Ragwort; we found it in the Dunson
Native Flora Garden. The next to bloom was the Butterweed that we saw along the
Orange Trail and in the flood plain by the power line. Now is the time for Small’s Ragwort to begin to bloom. To
the casual glance each of these species look very similar , but they differ
significantly in the shape of the basal leaves: Golden has rounded, kidney
shaped basal leaves, Butterweed has basal leaves that are long with many paired
lobes and Small’s has long, very narrow basal leaves. They also prefer
different habitats, Butterweed preferring moist areas like flood plains and the
other two preferring dryer habitats. Butterweed is also an annual plant; Golden
and Small’s are perennials.
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| English Oak leaf |
How trees can cope
with climate change. If you have lived in different areas of the United
States you are probably aware that the plants that grow in those areas are
often different. Growing up in eastern Kansas I noticed that our wooded areas
were filled with oaks, elms and hickories. But when we went to Colorado the
mountains were dominated by pines, spruces, firs and aspens. When I moved to
Michigan I found a different mix of trees that included Beeches and Maples. And
in Georgia, of course, there were Tulip trees, Magnolias, Sweet Gums and
numerous other kinds I had never seen before. From the perspective of my
relatively short human lifespan those were the forests typical of those
regions. But if I had been alive in eastern Kansas just a 100 years earlier I
could have looked far and wide without seeing any oaks or elms. And even longer
ago the upper midwest had no trees. It was covered by great masses of ice that
reached south to northeastern Kansas.
This perspective shows us that what we perceive as a
typical forest for our area is subject to change, change on a time scale that
exceeds a single human life, but change, nonetheless. When the climate changes
what is seen in the woods also changes.
Trees as individuals cannot move, but their progeny, in
the form of seeds, can be transported some distance from their parental origin.
Trees that produce wind dispersed seeds are an obvious example. But what of
trees like oaks that produce large, heavy seeds that lack wings?
An interesting scenario has been developed by European
botanists that suggests a way the oaks of Europe could have dispersed northward
after the glaciers retreated.
Two kinds of oak are found across most of Europe: English
Oak (Quercus robur) and Sessile Oak (Q. petraeus). Two animals are capable of
dispersing the acorns of these oaks, squirrels and jays. Like American
squirrels, European squirrels are scatter-hoarders – they gather acorns and
bury them within a short distance for future use during winter. Some of these
acorns survive, either because the squirrel forgets where it was hidden or
because of the death of the squirrel. But most acorns are buried within a short
distance of the nest, so this dispersal method is very slow and the spread of
oaks into recently glaciated areas would be slow indeed.
Fortunately the European Jay, like our Blue Jay, is a better
disperser of acorns. Jays have a large gullet, enabling them to hold several
acorns at a time. In addition, they fly large distances,as much as several
kilometers, before burying or concealing their acorns. Jays can remember
thousands of cache locations, enabling them to retrieve their acorns during the
winter.
The English Oak produces smaller acorns than the Sessile
Oak, so it is favored by the jays because they can carry more in one trip. As a
consequence, English Oak is thought to have dispersed out of its glacial
refuges in southern Europe faster than Sessile Oak.
But a tree has another way of dispersing. It can produce
pollen that is carried long distances by the wind. The European botanists
suggest that Sessile Oak pollen was blown into areas of English Oak established
by jays, and hybridized with those trees. This would establish a population
consisting of English Oak and English/Sessile oak hybrids. Over time the hybrid
oaks would cross with themselves, recreating trees that resemble Sessile Oak.
Meanwhile the English Oak acorns would be dispersed by jays to other areas
previously unoccupied by either kind of tree.
In this way, with English Oak leading the way, the whole
of Europe would come to be occupied by both kinds of oaks, as well as their
hybrids. This is the situation that exists today in Europe.
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| American Wisteria inflorescence |
American Wisteria,
Wisteria frutescens, is blooming at
present. It can be found at two places in the Garden: growing on the bridge
approaching the Meditation Garden and on the wood fence next to the road at the
bottom of the Dunson Garden. This native species is not invasive like its
imported relative Chinese Wisteria, Wisteria
sinensis, a plant that is notoriously difficult to control. Almost as bad
as Kudzu, the Chinese Wisteria easily escapes its garden confines and rapidly
spreads, growing into the tops of trees which it then begins to kill by shading
them.
The two species differ in other respects. Chinese
Wisteria has longer compound leaves with leaflets that have “wavy” edges, i.e.,
instead of the leaflets being flattened, their edges curve up and down like the
surface of the ocean. Flower clusters are much longer than in American Wisteria
and the fruits are flattened and covered with fuzz. The flowers also usually
appear before the leaves emerge in the spring. American Wisteria flowers appear
after the leaves have emerged and the fruits are smooth and cylindrical. It is
also much easier to control.
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| Eastern Columbine flower in normal, downward pointing position. |
The plantings at the edge of the Meditation Garden have
several kinds of Columbines. One is Eastern
Columbine, Aquilegia canadensis; the
others are columbines found in the western US. I hesitate to give them names
because these plants hybridize easily and numerous color and shape varieties
have been created by the horticultural trade.
Eastern Columbine flowers face toward the ground and have
red petals with prominent nectar spurs. The red color suggests that they are
pollinated by hummingbirds and this is supported by photographic
evidence.
One of the columbines in the Garden resembles a western species –
Crimson Columbine, A. formosa. It
also has a flower that faces downward, but the nectar spurs are much longer
than the Eastern Columbine and the petals larger and spread out more.
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| Crimson(?) Columbine; same downward posture as Eastern Columbine; longer nectar spurs and petals spread and some colored white. |
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| Colorado (?) Columbine; all white, very long nectar spurs, blossom facing upward; Hawk moth pollinated. |
A third type in the Garden’s collection might be a
Colorado Columbine, A. coerulae,
which has a white variety. Instead of the flower facing down, this species
holds the flower with the opening facing the sky. The light color and upward
orientation, along with the long nectar spurs suggest that it is visited by
Hawk Moths. (Hawk Moths are about the size of a hummingbird and can fly like
one, hovering over a flower and sucking up nectar through a proboscis that is
often longer than the body and held in a coil beneath the moths head. This webpage
has a photo of a hawkmoth nectaring at a white A. coerulae. Since they feed at night hawk moths can visually find
the white flowers very easily.)
But Eastern
Columbine presents a mystery for biologists. In spite of the fact that its
flowers can be visited by bees and hummingbirds, genetic analysis of the seeds
show that >95% result from self-pollination. So why does the flower produce
copious amounts of nectar to attract hummingbirds? If most of the seed is
produced by selfing you would think that a plant that stopped nectar production
could produce more seed than one that diverted energy into making nectar. At
present there is no satisfactory answer. That’s one of the things that makes
biology so interesting.
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| Northern Red Oak showing the "ski trail" bark feature. |
Northern Red Oak
has bark with “ski trails,” really just bark with flattened ridge tops that are
light colored. The leaves are lobed and each is pointed and tipped with a small
bristle, a characteristic of the red oak group.
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| Winged Elm bark |
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| Corky "wings" on a twig of Winged Elm |
Winged Elm has
a distinctive bark that is hard to describe. The feature that gives it its
common name is sometimes hard to find. The “wing” is a corky ridge found on
some of the branches and twigs. Some plants have many winged branches while
others have only a few.
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| Open flowers and buds of American Euonymus (Hearts-a-Bustin') |
Hearts-a-Bustin’
is the name by which American Euonymus is known in the fall when the fruits
ripen. But know it has the flowers that will produce that fruit. Each rather
nondescript blossom is displayed against a leaf, making it a lot more obvious
to potential pollinators.
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| The black area is the spore-producing surface of the Hypoxylon sp. fungus that killed this tree. |
On previous rambles we have noted a tree by this path
that is infected with the Hypoxylon fungus. It had sloughed
off pieces of bark, revealing shiny dark patches beneath. These black areas are
the locations where Hypoxylon spores
are produced. This year we see the conclusion of this story – the tree has
fallen over. It seems that Hypoxylon
is not the sole reason for its demise, though. Wikipedia tells us that Hypoxylon just finishes off a tree that
has already been weakened by a previous infection.
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| The purple flowers of the Eastern Anglepod vine. |
Growing on the deer fence near the entrance to the Orange
Trail is a Carolina Spinypod vine, Matalea carolinensis, that we have seen in
this location for the last four years. It is a member of the Apocynaceae
family, the Dogbane family, to which the milkweeds now belong. Like the
milkweeds the dogbanes have latex canals and exude a sticky white fluid when
the leaf or stem is injured.
Can Monarch
butterfly caterpillars eat Matelea?
Because dogbanes and milkweeds are related it might be reasonable to assume
that they could be used as a host plant by the Monarch butterfly. I have seen
and heard from several sources that Monarchs do not use dogbanes as a larval
food, but I’ve been unable to document this. One internet resource, the Finger
Lakes Native Plant Society, says that Monarchs use Spreading Dogbane as a
larval host plant and cites a reference. But the editor
of the Society added a note refuting this assertion.
“Editor's note Jan. 2014. Following up on a reader's
question suggests that references to monarchs utilizing Apocynum may be a case
of repeated references to an original, erroneous report. Robert Dirig,
Cornell, states the following:
‘Here's a quote from a long essay on the Monarch that I wrote a
few years ago:
Confined N.Y. females refused to oviposit on Spreading Dogbane
(Apocynum androsaemifolium, Apocynaceae), nor would larvae eat it.
Literature reports of this plant as a Monarch larval host may be
misidentifications, since dogbanes also contain milky latex and superficially
resemble slender milkweeds.
I have never found a wild larva on
either Spreading Dogbane or Indian Hemp. Female Monarchs also would not lay
eggs on local Vincetoxicum/Cynanchum species, and larvae wouldn't eat
them. In the Northeast, they seem to be confined to milkweed hosts
(Asclepias).’”
So, just to muddy the waters a little further, here is my
observation. About 20 years ago I was visiting a friend in Indiana. His
property is adjacent to a cornfield and was walking nearby when I saw a Monarch
flying in a manner that suggested she was searching for a place to lay eggs.
Milkweeds are common in corn fields in the Midwest (or they used to be, before
glyphosate resistant corn came into common use). I followed the Monarch and saw
her lay an egg on a sprawling vine growing among the corn stalks. After she
flew off I examined the leaf where she had landed and confirmed that she had
laid an egg on it. I grabbed a sample of the plant and returned to my friends
house to identify it. It was a vine in the genus Matelea, according to Dean’s Plants of Indiana. I should emphasize
that I only saw one Monarch lay one egg on that one plant. I don’t know if the
caterpillar would have survived on the plant.
Another
publication available on the internet lists several non-milkweed host
plants for Monarch larval development, including Matelea spp., but without citing specific references for the
information. It is produced by/for the state of South Carolina and appears to
be reliable.
Why would a butterfly like a Monarch lay its eggs on an
inappropriate host plant? Butterflies identify host plants by “tasting” them.
The taste organs are in their feet. A female flies around and when she sees or
smells a plant that appears to be suitable food for her caterpillars she will
touch it with her taste it with her feet, something like a child licking
something to see if its good to eat. Dogbanes may “taste” like milkweeds
because they contain the same chemicals due to their familial relationship.
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| A Field Poppy in full color |
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| Imagine this sight marking each grave. |
In the Flower Garden we saw large numbers of the European
weed, Field Poppy, Papaver rhoea. This plant has an
interesting connection to UGA. You may have noticed that US29 from Athens to
Winder has signage stating that it is “Moina Michael Highway.” Moina was
teaching at the Normal School in Athens when the US entered WWI. She took a
leave of absence from her position and joined the war effort. After the
armistice she returned to teaching at UGA and taught a class with disabled war
veterans. She became concerned with the lack of support and occupational
training for these veterans and had the idea of raising money for them through
the sale of artificial red flowers, “Buddy Poppies.” She had been inspired by this
poem written by a Canadian officer during the war:
In Flanders Fields
By John McCrae
In Flanders
fields the poppies blow
Between the
crosses, row on row,
That
mark our place; and in the sky
The
larks, still bravely singing, fly
Scarce heard
amid the guns below.
We are the
Dead. Short days ago
We lived, felt
dawn, saw sunset glow,
Loved
and were loved, and now we lie,
In
Flanders fields.
Take up our
quarrel with the foe:
To you from
failing hands we throw
The
torch; be yours to hold it high.
If
ye break faith with us who die
We shall not
sleep, though poppies grow
In
Flanders fields.
I can remember being encouraged to buy a paper “Buddy
Poppy” when I was in grade school. I was sent off to school with a dime on the
day the paper poppies were available, but I wasn’t really clear about what they
represented.
Why the Field Poppy became a symbol of the war is due to
its biology. The Poppy was considered a weed by European farmers. It is an
annual that produces a prodigious amount of seed that lays dormant in the soil
until it is unearthed and brought to the surface. Each attempt to prepare a
field for a new crop brought up fields of poppies that had to be eradicated. In
the war years there was little agricultural production in the war zone, but the
soil was regularly disturbed by two activities: artillery shells and grave
digging. Each resting place became marked with a rectangle of brilliant red
blooms, symbolic of the blood that had been shed.
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| Pearl Millet seed head |
Jeff and his wife lived in Africa some years ago. He
pointed out to us a few plants that we know as ornamental grasses, Pennisetum sp., but are known in Africa
as Pearl Millet, an important dry-land crop. Jeff told us about his work trying
to find a way to decrease the damage a bird, called the Quelea does to millet
in Africa. This bird travels in immense flocks that descend on fields of grain
and destroy the crop in short order. One natural strain of millet has evolved
long, pointed spikes in the seed heads to reduce the damage done by the Quelea
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| A bee-mimic hover fly gathering pollen from a Bachelor's Button. |
Where are all the
bees? As we wandered through the Flower Garden and the other formal Gardens
we kept our eye open for bees and butterflies. It was nearing 11:00 am and
quite warm, but insect life was conspicuous by its absence. Is it possible that
the cold spring we’ve experienced retarded the development of bees and other
pollinators? Another mystery to solve!
SUMMARY OF SPECIES OBSERVED
Common Name
|
Scientific Name
|
Small’s Ragwort
|
Packera anonyma
|
English Oak
|
Quercus robur
|
American Wisteria
|
Wisteria frutescens
|
Northern Red Oak
|
Quercus rubra
|
Jack-in-the-Pulpit
|
Arisaema triphyllum
|
Hypoxylon fungus
|
Hypoxylon sp.
|
Carolina Spinypod
|
Matalea carolinensis
|
Field Poppy
|
Papaver rhoea
|
