Today's Ramble was led by Dale Hoyt.
The photos in this post, except where
noted, came from Don's Facebook album (here's the link).
Today's post was written by Dale Hoyt & Linda Chafin.
27 Ramblers met today.
Announcements:
1.
Emily reminded us that Saturday, April 28th,
the Friends of the Georgia Museum of Natural History will be holding their
annual meeting at the museum annex at 12:00 p.m; all Ramblers are invited to
view the research collections at 1:00 to 2:00 p.m. Music and refreshments
available as long as they last.
2.
The next Oconee Rivers Audubon Society meeting (May
3rd) speaker will be Hans Neuhauser, a national expert on Right
Whales. (Location: Sandy Creek Nature Center.)
3.
May 2nd, Emily will be leading the
First Wednesday nature walk at SCNC.
Coffee and treats afterward.
Today's reading: An excerpt from
David George Haskell's book, The Song of Trees, pp. 179-180:
Whether all these natural phenomena are wise, beautiful, just, or
good are different questions. Such puzzles are best resolved by beings who
understand themselves to be nature. Muir said that he walked "with
nature," a companion. Many contemporary environmental groups use language
that echoes Muir, placing nature outside us. "What's the return on
nature?" asks the Nature Conservancy. "Just like any good investment,
nature yields dividends." The masthead of the Royal Society for the
Protection of Birds, Europe's largest environmental group, promises that the
organization is "giving nature a home." Educators warn that if we
spend too long on the wrong side of the divide, we'll develop a pathology, the
disorder of nature deficit. In the post-Darwin world of networked kinship,
though, we can extend Muir's thought and understand that we walk within. Nature
yields no dividends; it contains the entire economy of every species. Nature
needs no home; it is home. We can have no deficit of nature; We are nature,
even when we are unaware of this nature. With the understanding that humans
belong in this world, discernment of the beautiful and the good can emerge from
human minds networked within the community of life, not human minds peering in
from outside.
Today's route:
We walked over to the arbor and took the sidewalk
to the right, down through the Lower Shade Garden. From there we walked through the upper
section of the Dunson Native Flora Garden exiting onto the road and walking
down to the power line, where we headed for the ephemeral pool. We returned to
the Visitor Center on the White Trail Spur.
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| Ozark Witch Hazel leaves |
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| American Witch Hazel conical gall most of the galls were green |
In the Shade Garden, on the
left, just after the first switchback, is a clump of small trees/shrubs: ozark
witch hazel, naturally found in the Ozarks of Missouri. Immediately adjacent is
a small common witch hazel, found widely in eastern deciduous forests. Just
looking at the shape of the leaves these are nearly indistinguishable, but the
leaves of the common witch hazel are covered with conical galls shaped like a
halloween witch's hat. Close examination of the ozark witch hazel found only
one or two weakly developed, similar galls. Apparently the gall-forming insect
can tell the difference between the two witch hazel species.
The galls are induced by an
aphid, Hormaphis hamamelidis, that
lays an egg in the tender young leaf of the tree. Something injected with the
egg or produced by the hatching aphid inside the leaf causes the leaf tissue to
swell and produce the "witch's hat." Meanwhile the aphid inside the
gall not only feeds, but reproduces asexually (parthenogenesis). These
daughters also reproduce asexually and soon the interior of the gall is
swarming with tiny aphids. Toward the end of spring some of these develop wings
and fly to an alternate host, River Birch, where they start feeding on the
birch leaves and producing more aphids (wingless this time). As fall approaches
some of the birch aphids produce winged male and female offspring and the mated
females fly to witch hazels and lay eggs on the leaf buds, completing the
cycle.
Many aphids have a similar life
cycle in which they alternate between different host plants and produce winged
or wingless forms, either sexually or asexually. The world is stranger than you
imagine or, in some cases, stranger than you can imagine.
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| Forest Tent Caterpillar |
Near the witch hazels Don found
a caterpillar that resembled that of the Eastern Tent Caterpillar moth. You've
probably seen their silken tents in the crotches of cherry trees in the early
spring. But this was a little different in appearance and turned out to be a
related species, the Forest Tent
Caterpillar moth. Unlike its commoner relative, the Forest species does not
construct a tent, but its caterpillars are still gregarious and travel together
to feed on the leaves of their host plants. The feed on a greater diversity of
plants than the Eastern species, including Sweet Gum, Maples and Hickories.
Here is how you can tell the caterpillars apart, according to bugguide.net (Italics
added for emphasis.):
Forest: "dark-gray to brownish-black background body color,
highlighted by broad, pale-blue lines and thin, broken yellow lines extending
along each side; dorsum of each abdominal
segment has distinct whitish keyhole or shoeprint-shaped marking; body has
fine, whitish, and sparsely distributed hairs."
Eastern: "distinguished
by a solid cream/white line along the dorsum (middle of the back). Sides of
the body are marked with blue, black, orange and white. Dark face."
The Eastern species doesn't do
much damage to its host tree, just defoliating a few branches. The Forest species
sometimes erupts and can defoliate a large number of trees, but such damage is
usually only seen at decade intervals.
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| Redshouldered Hawk nest in Sycamore |
In this same area of the Shade
Garden is the nest of a Red-shouldered Hawk in the crotch of a young Sycamore
tree. We could just make her out with binoculars as she incubated her egg(s).
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| Florida Anistree flower |
Further along, the Florida
Anisetree we saw the last time we were in this part of the Garden has dropped
most of its petals. We'll have to return to see if any fruits develop.
Tree identification is often
difficult when a tree is so tall that you can't see the leaves. Fortunately,
many trees have characteristic bark that distinguishes them. Two such species
are White Oak and Northern Red Oak.
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| White Oak bark |
When White Oak is young its bark
is light gray and in narrow, overlapping plates, like shingles. As it ages, the
bark on the lower part of the tree darkens and becomes "blocky,"
losing the shingled appearance.
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| Northern Red Oak with shade leaves |
The bark of Northern Red Oak (NRO)
is ridged and the top of the ridges is smooth and lighter in color, yielding a
striped appearance. It reminds some of ski trails and, since they can only ski
in the north, they remember that the Northern Red Oak has ski trail bark.
The NRO had some leaves
sprouting from its base as well as some growing about 12 feet above. This made
for easy comparison of what are called "shade leaves" and "sun
leaves."
Near the forest floor the light
has been intercepted by the canopy of leaves above and only a fraction of its
energy remains. The shade leaf can increase its ability to photosynthesize by
increasing its area – becoming broader. When a leaf becomes broader it risks
losing more water, but near the ground the wind is blocked by surrounding
vegetation so even broad leaves don't lose a lot of water. As you go up to the
canopy the leaves get smaller and thicker. Smaller to reduce water loss and
thicker because the sunlight is more intense and the leaf can devote more cell
layers to capturing the light for photosynthesis.
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| Tulip Tree flower |
One of the tall trees that is
insect pollinated is the Tulip Tree, sometimes known as Tulip poplar or Yellow
poplar, even though it is not a poplar. Tulip Tree flowers are seldom seen
since they are held high on the tips of upper branches. Only when a storm or a
squirrel drop them to the ground do we get to admire their vivid colors and
pleasing symmetry. This flower was found on the road beneath a mature Tulip
Tree and was swarming with ants, eager to reach the abundant nectar produced by
glands in the orange-colored portion of each petal. Normally, ants would have
no chance to reach these high-elevation flowers that are typically visited by
beetles, bees, and other flying insects.
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| Black Cohosh with beginning of inflorescence |
At the edge of the Dunson Native
Flora Garden there are several Black Cohosh that have started to bolt. (Bolting
means that the flower stalk is rapidly elongating.) This stalk can reach six to
eight feet high will be covered with hundreds of white flowers in a few more
weeks. Black Cohosh was used by native americans to treat "female
conditions."
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| Solomon's Plume (AKA False Solomon's Seal) |
Among the Black Cohosh we found
a single flowering Solomon's Plume, a plant that is often called "False
Solomon's Seal." This prompted a discussion of common names and, in
particular, why some feel that it is inappropriate to refer to a plant as
"False."
Opponents of using False:
1.
How can a plant be false?
2.
Shouldn't a plant name emphasize a feature of
the plant, rather than something it isn't?
3.
If a number of plants all resemble the same
plant, then they would all be called, for example, False Dandelion, leading to confusion.
Proponents of using False:
1.
If it's a common name and people have commonly
used "false" to describe a plant, why manufacture an artificial name?
Common names should be those that are common use.
2.
The use of "false" doesn't mean the
plant is false. It means that it resembles another plant enough to cause
confusion for in observer. No one objects to "false face" or
"false door."
3.
Where false leads to confusion, as with the
Dandelion example, then the "false" species should have their names
changed for clarity.
What is your opinion?
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| Early Meadow Rue fruits |
Earlier in the spring, Ramblers
admired the somewhat showy, dangling stamens in the flowers of male Early
Meadow-rue plants. The flowers on the nearby female plants were miniscule in
comparison but have now come into their own since the ovaries have developed
into fruits. Each 3mm-long fruit is tipped with the withered remains of the the
style and stigma that conveyed pollen to the ovules contained in the ovaries.
Species that bear female (pistillate) flowers and male (staminate) flowers on
separate plants are called dioecious (pronounced "die--ee--shus"), which
is Latin for "two houses." Separating female and male flowers onto
separate plants is an extreme solution to the challenge of preventing
self-fertilization.
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| Virginia Snakeroot |
It was a personal treat for me
when Linda found Virginia snakeroot. This is the foodplant of the Pipevine
swallowtail and I've been trying to see one for a long time. Like the Monarch,
the swallowtail's caterpillar stores the poisons it picks up from eating the
plant. The adult butterfly becomes toxic and distasteful and protected from
predators like birds. It has served as the distasteful model for several
species of butterflies in Georgia: Black Swallowtail, the dark form of the
female Tiger Swallowtail, Spicebush Swallowtail and Red-spotted Purple. All
these species share the same appearance: Black upper surface of the wings and
the hind wings have broad areas of blue or greenish pigment. The upper hind
wing surface of the Pipevine Swallowtail model has a bluish or greenish
iridescent coloration, depending on the direction of viewing.
A useful characteristic for identifying
plants of all types is the way their leaves are attached to their stems or
twigs. There are two main patterns: alternate
and opposite. (There is actually a
third, but we'll save that one for another ramble.) Opposite leaf arrangement means
that where you find one leaf attached to a stem or twig you will find a second
leaf 180 degrees from the first, on the opposite side of the same stem or twig.
Thus, the leaves are arranged in pairs as you go up the stem or toward the tip
of the branch or twig. But how are adjacent pairs of leaves arranged? In the
great majority of plants with opposite leaves successive pairs are found
shifted 90 degrees from the pair below them (and the pair above). This
arrangement allows the lower leaves to get more sunlight because the leaf pair
above them doesn't shade them. (They will get some shade from the second pair
above, but these will be further away so some sunlight will still get through.
Some common local trees or
shrubs that have opposite leaves are: Maples, Ash, Dogwood and Buckeye; the
family of herbs have opposite leaves.
The plants with alternate leaves
have a clever way of arranging successive leaves. Each leaf is oriented
approximately 137 degrees clockwise or counterclockwise from the leaves below
and above. This pattern minimizes the shading of lower leaves. It can be seen
best in saplings small enough for you to look directly down on them.
Among trees many more have
alternate leaves than have opposite leaves. In our area Oak, Birch, Hickory and
Elm, just to name a few familiar kinds, have alternate leaves.
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| The compound leaf of a hickory |
One complication: you have to
know what a leaf is to determine how it is arranged. Some trees have what are
called compound leaves – leaves that
are made of smaller leaflets. Hickories are a good example. A Hickory compound
leaf with, say, 7 leaflets will have three pairs of opposite leaflets and one
terminal leaflet, an arrangement that is termed pinnately compound. So how do you know when you're looking at a
leaflet and when you're looking at a leaf. The secret is that at the base of a
leaf there will be a bud. (The bud contains the embryonic leaf that will be
produced next year.). Leaflets will lack a bud at their attachment point.
Of course many trees just have
simple leaves: Oaks and Elms have simple, alternate leaves; Hickories have
pinnately compound, alternate leaves; Ash trees have pinnately compound,
opposite leaves. You'll learn to identify these and others as we ramble through
the year.
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| Mosquito "wrigglers" |
The heavy rains this week have
filled the temporary pool in the power line and it is swarming with mosquito
larvae, commonly called "wrigglers." Don was able to a photograph of
several as they danced about the water. This low lying area frequent retains
water after heavy rains are is a favorite place of several kinds of frogs to
breed. Earlier in the year we saw the egg masses of Leopard frogs and in the
past we've seen the paired strands of American Toad eggs. One of regular
ramblers, Rosemary, was unable to attend Thursday, but she came out to the
Garden Wednesday evening and made a short video of this area. You can hear a loud
chorus of Spring Peepers (the deafening whistled "peeps") and
another, quiter, low pitched "grrrrrrrr" that I think is a Gray Tree
Frog. Rosemary's
video and other photos are on our
Nature Rambling facebook page.
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| Floodplain filled with water behind the river levee |
Another area that regularly
floods after heavy rainfall is the floodplain behind the river levee. This
is an important breeding area for Marbled Salamanders. They lay their eggs in
the fall, under rotting logs and leaf litter where it is moist. The female
remains with the eggs and, if she is fortunate, winter rains will bring enough
water to flood the area and hatch her eggs. They get a head start developing
ahead of the spring breeding salamander species.
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| Red Maple leaf (L.) compared to Chalk Maple leaf (R) Note the smoother edge of the Chalk Maple and the difference in pointedness of the central lobe; Chalk Maple has squared shoulders. |
SUMMARY OF OBSERVED SPECIES:
|
Ozark Witch-hazel
|
Hamamelis
vernalis
|
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American Witch-hazel
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Hamamelis
virginiana
|
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Forest Tent Caterpillar
|
Malacosoma
disstria
|
|
Red Shouldered Hawk
|
Buteo
lineatus
|
|
Beal's Barberry,
Leatherleaf Mahonia |
Mahonia
bealei
|
|
Florida Anisetree
|
Illicium
floridanum
|
|
White Oak
|
Quercus
alba
|
|
Northern Red Oak
|
Quercus
rubra
|
|
Tulip Tree
|
Liriodendron
tulipifera
|
|
Black cohosh
|
Actaea
racemosa
|
|
Solomon's Plume
|
Maianthemum
racemosum
|
|
Atamasco Lily
|
Zephyranthes
atamasca
|
|
Hickory
|
Carya
sp.
|
|
Virginia Snakeroot
|
Aristolochia
serpentaria
|
|
Pale Yellow Trillium
|
Trillium
discolor
|
|
Crossvine
|
Bignonia
capreolata
|
|
Perfoliate Bellwort
|
Uvularia
perfoliata
|
|
Early Meadowrue
|
Thalictrum
dioicum
|
|
|
|
|
Beaked Corn Salad
|
Valerianella
radiata
|
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Butterweed
|
Packera
glabella
|
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Mosquito
|
Family Culicidae
|
|
Rue Anemone
|
Thalictrum
thalictroides
|
|
Chalk Maple
|
Acer
Leucoderme
|
|
Red Maple
|
Acer
rubrum
|
|
Box Elder
|
Acer
negundo
|
|
Jack-in-the-Pulpit
|
Arisaema
triphyllum
|
|
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