Today's Ramble was led 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, unless otherwise credited.)
Today's post was written by Linda Chafin (plants) and Dale Hoyt (animals).
28 Ramblers met today.
Announcement: Ed told us about the recent meeting
of the Athens Community Tree Council, an
organization dedicated to promoting and protecting Athen’s tree canopy. The council is composed of fifteen volunteers (currently looking for
a volunteer to fill a vacancy) and is trying to revitalize itself. It provides guidance to government officials
on issues regarding tree planting and removal but because of a number of
unspecified issues, the tree ordinances are not typically enforced. The council needs volunteers and donations.
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| Black Swallowtail butterfly; newly emerged from its chrysalis. (click to enlarge) |
Show and Tell: Berkeley told us that we might see a newly eclosed Eastern Black Swallowtail butterfly later this morning. After the Ramble, Don found that one had emerged from its chrysalis while we were on our Ramble. Several interested ramblers took the opportunity to see the freshly emerged butterfly.
Today's reading:
Dale read Donald Culross Peattie’s commemoration of Alexander von Humboldt’s
birth date, September 14, 1769:
ON THIS
day in 1769 was born
Alexander von Humboldt, who
has been called the second
discoverer of America. In 1799 he put his entire fortune into an expedition
to South America where he made collections
so vast that much of the
remainder of his life was spent in working
them up at Paris
and in Berlin.
Never
did there live a man of more varied
attainments.
Humboldt
is the real founder of climatology,
the inventor of the
weather map; he was the discoverer
of the fact that volcanoes exist
in ranges along cracks in the earth's surface;
he is the Adam of modern geographers,
the model of modern
exploration; he experimented, largely
on himself, with the
effects of electricity upon muscles and nerves; he
founded plant geography as a science,
and to cap it all he
undertook in his old age to write a Kosmos
that was the
summum bonum of romantic natural philosophy.
He died in the year that
Darwin published the Origin of Species.
With
all these gifts, Nature had yet endowed him with
the talents of an artist, and it is to his esthetic
appreciation of scenery and his vivid
descriptions of the delights of travel that
the popularity of his Travels is
due The armchair explorer never had a better friend than goodly
Humboldt. So far as scenery can
ever be reduced to a science-
that is, classified by types - Humboldt
did it, by combining knowledge of geologic structure with a keen feeling
for the types of vegetation. He declares
that each latitude possesses its own characteristic natural "face."
I
have more than backward looking
tenderness for this concept and for Humboldt's versatile
gifts; I am of the conviction that a sort of synthetic diffuseness
is exactly what science, more than ever, stands in want of.
Today's
Route: We took the
paved path to the Flower Bridge and followed the path across the bridge to the
Purple Trail trailhead. We followed the Purple Trail to the river and turned
right onto the Orange Trail, which we took upriver until the Orange Trail Spur,
from which we returned to the Visitor Center via the White Trail and the
Children’s Garden. We then enjoyed conversation and refreshments at the Café
Botanica.
LIST OF
OBSERVATIONS:
Paved
Path to Flower Bridge:
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| Appalachian Turtlehead (click to enlarge) |
On our way to the river, we passed a patch of Appalachian
Turtleheads, a cultivar named ‘Hot Lips,’ planted in the Bartram section of the
International Garden. This native species barely makes it into Georgia, with
only one population in Rabun County, a stone’s throw from North Carolina. It is
more common but still rare in moist, high elevation forests in North Carolina,
South Carolina, and Virginia. From the side, its flowers resemble–sort of–a
turtle’s head. The large, nearly closed flowers suggest a large, strong
pollinator and, as we watched, a bumblebee forced its way between the “lips”
into the inflated part of the flower where the stamens and pistil are held.
Some
people asked if a cultivar is always a hybrid–the answer is no. Cultivars are plants
that have been selectively bred by farmers, horticulturists, and plant breeders
to achieve some human goal: showier
flowers, improved yield, disease resistance, etc. The breeding may take the
form of crossing plants (from either the wild or the garden) with the desired
characteristics with each other or by crossing a plant with itself (self-fertilization)
in hopes that the resulting plants will “come true” from seed, with the desired
trait. This is an uncertain outcome, so more often the selected plants are
propagated by rooting some vegetative part of the plant (asexual reproduction) resulting
in a clone–anyone who has put a stem of basil in a glass of water in order to
root it has engaged in plant cloning! Rarely does selective breeding involve hybridization
between two different species but it may happen. In agricultural plants,
cultivars may be GMOs, i.e. a line of
plants formed from the deliberate introduction of genes from a different kind
of organism into the plant. Once the
desired plant has been achieved, its creator may name it. In the case of ‘Hot
Lips’ the desired trait was deeper flower color. Since a cultivar name is not
in Latin, it is not italicized but instead enclosed in single quotation marks
following the scientific name. Don’t confuse ‘cultivar’ with variety, a
naturally occurring variation that happens in the wild.
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| Underside of a Bigleaf Magnolia leaf (click to enlarge) |
The Bigleaf Magnolia planted in the Bartram section is beginning to drop its leaves, giving us the chance to see just how big they are (up to 30 inches long)–its leaves are the largest simple leaves of any native North American tree. The white, waxy coating on the lower leaf surface reduces moisture loss from the epidermal cells on the leaf. The stomates that open and close on the leaf surface to admit CO2 and release O2 are not coated. (click to enlarge)
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American toad;
spotted by Clay, grandson of Betsy. (click to enlarge)
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Threatened
and Endangered Plants Section:
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| Ovate Catchfly (click to enlarge) |
Ovate Catchfly is in flower in the Threatened and
Endangered section of the International Garden. This species is rare throughout
its range in the southeast and lower Midwest. Its flowers actually have only five
petals but each is divided into eight very narrow segments, giving the flower a
frilly look. In Don’s photo you can see how the stems are covered with short
hairs–these hairs are tipped with tiny glands that produce a sticky,
insect-trapping mucilage (hence, Catchfly). The plant doesn’t eat the insects
in the way a sundew might; the hairs prevent ants from reaching the flower and
its nectar, which is best saved for more efficient pollinators.
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| Joro Spider (click to enlarge) |
The Joro Spider, a native of Japan, was recently (2015)
found for the first time in North America. This spider is related to the Golden
Silk Orbweaver (AKA Banana Spider), Trichonephila clavipes, found in
coastal areas of Georgia and South Carolina, as well as Florida. Because the Joro Spider was only
discovered in the United States four years ago no one knows what impact, if
any, it will have on our native fauna. The spider was first identified by Rick
Hoebeke, Associate Curator at the Georgia Museum of Natural History. Here’s a link to the paper announcing
its discovery.
Purple Trail:
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A recently windthrown Sourwood tree presented us with an opportunity to
see the fruits, normally found high in the top of the tree. (click to enlarge)
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Possumhaw Holly is beginning to show signs of
fall. (click to enlarge)
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Hollow log (click
to enlarge)
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This hollow log is probably the remains of one of
the many Northern Red Oak trees that have come down at the Garden in the last
decade. Someone asked: how was it
hollowed out–why is it rotting from the inside out, rather than the outside in?
This tree likely had “heart rot” before it was toppled. A tree’s “heart” is the
non-living tissue in the core of the trunk–the remains of cells stacked end on
end that once carried water from the roots to the very top of the trunk. Over
time these cells were displaced inward and died as new, living wood was laid
down around the circumference of the tree. Fungi invade through a wound in the
bark and when they reach the heartwood, they soften and digest it. The living
wood around the circumference of the trunk is not affected, and the tree can
live for many years with heart rot. But once the tree dies, the softened
heartwood rots more quickly than the outer hull of the tree. Pine trees rot
from the outside in because their heartwood is loaded with rot-resistant resins
and other compounds. Pine heartwood is the source of fatwood or fat lightr’d
long used to light fires.
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Eastern Fence Lizard basking on fallen tree
(photo) (click to enlarge)
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Orange Trail:
Our
goal today was to learn some of the trees that make up the floodplain forest
along the Middle Oconee River.
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| Musclewood trunk(click to enlarge) |
One of the most common and easily recognizable trees
in the floodplain is Musclewood, so named because the trunk looks sinewy and
muscular. It’s also called Ironwood for its heavy, hard, and close-grained
wood. Beneath the lichens, the bark is actually quite thin; living in moist
areas, these trees are rarely subject to fire and have not developed thick
protective bark of upland oaks and hickories. Musclewood is a slow-growing
understory tree, rarely reaching heights of 35 feet.
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| Eve examines the leaves of a stump sprout at the base of a large River Birch growing on the levee. (click to enlarge) |
River Birch is the only birch species in the
Piedmont and in the wild is found mainly on river levees and streambanks. It is
shade-intolerant and rapidly grows into the canopy, up to 100 feet, or grows
sideways out over the river to reach the light. The bark of older trees is
thick, flaky, and spongy. Younger trees and branches high up in the canopy of
old trees have beautiful pale, exfoliating bark that peels away to reveal
layers of rust-colored inner bark.
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Two
entwined floodplain plants: Yellow Crownbeard with Climbing Hempvine
(click to enlarge) |
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| Smooth Ground Cherry (click to enlarge) |
Smooth Ground Cherry, native to the
eastern U.S. and further south into the tropics, are in the same genus as Tomatillos
or Husk Tomatoes (Physalis ixocarpa)–
the resemblance is clear. Both have edible fruits surrounded by an inflated,
papery calyx. It’s also in the same genus as the ornamental Chinese Lantern (Physalis alkenkengi) that has an orange
husk.
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| Tulip Tree (click to enlarge) |
Tulip Trees (Tulip Poplar, Yellow Poplar) are common components of the floodplain forest, but they are also common in almost all Piedmont forests. It’s a pioneer species, invading newly opened gaps in the forest canopy or open, disturbed areas such as old fields. They grow relatively fast but have dense wood unlike some fast-growing trees and can reach heights of 100 feet in their long lives (up to 500 years). Never was a tree more inaptly named: it’s neither a tulip nor a poplar but a magnolia!
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| Winged Elm (click to enlarge) |
Winged Elm is also common in our
floodplain and in the uplands. The lower trunk of this tree is covered with burls
that have distorted the bark. Burls result from an invading pathogen such as a
virus or fungus or from an injury or insect damage. There’s no way to know what
attacked this tree but it seems to be fine now; the excessive growth of the
burl often isolates the pathogen and prevents it from harming the rest of the
tree. The characteristic “tongue depressor” bark of winged elms is obscured by
the almost continuous cover of burls on the lower half of the trunk. Burls
often have buds in them that produce short, leafy twigs.
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| Sycamore leaves (click to enlarge) |
Sycamores are floodplain trees with
characteristic “camo” bark that is patterned gray, green, tan, and white. The outer,
colored bark falls off the tree, revealing the white inner bark, as the trunk
and branches expand laterally and the inelastic bark breaks into plates or
flakes. If the tree has had a good year and grown a lot, it will shed lots of
bark. Sycamores can grow to 130 feet in height and nearly 7 feet in
diameter–that’s a lot of shed bark! Sycamores have interesting leaves: they are
shaped like extra-large, raggedy maple leaves; the base of the leaf stalk
appears swollen but in fact encloses and hides the axillary buds; and, the base
of the leaf stalk is surrounded by green, circular, leaf-like structures called
stipules.
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Sycamore bark (click to enlarge)
Photo credit: Janie K. Marlowe at www.namethatplant.net |
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Sycamore bark (click to enlarge) Photo
credit: Kretyen at Wikimedia Commons
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Sycamore twigs grow in zigzag fashion. (click to enlarge)
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Sycamore twigs grow in a zigzag fashion. This
happens because the leading bud at the tip of the twig always aborts, and the
closest lateral (side) bud grows instead–at an angle. The twig that forms from
that bud does the same thing except this time the lateral bud that expands at
an angle is on the other side of the twig–hence: zigzag.
Two common floodplain trees look a lot alike: Green
Ash and Box-elder. Both have opposite, compound leaves and spongy, braided
bark. Here’s how to tell them apart: Green Ash leaflets have no or only very
low teeth along their margins; Box-elder leaflets are markedly toothed. Green
Ash twigs are pale gray-green (ashy); Box-elder twigs are a bright, olive
green.
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| Inosculating Winged Elm (L) and Northern Red Oak (R) (click to enlarge) |
Don’s
photo of a Winged Elm and Northern Red
Oak “bonded” gave me the chance to learn another new botanical term:
inosculation. This is what happens when two trees–usually of the same species
but not always–grow very closely and rub together as the wind blows. The bark
wears away from both trees and exposes their cambium layers–rapidly dividing
and growing cells just under the bark. If the cambium of the two trees touches
for long enough, the cells can grow together or self-graft. Such couplings are
called conjoined trees or husband-and-wife trees. There is no sharing of genes
so the two trees retain their genetic identities. The tree on the left is a
Winged Elm (see the tongue depressors?), the tree on the right is a northern
red oak.
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| Silverbell occurs in several places along the White Trail, always in the floodplain. We’ll have to wait for fruit and flowers to identify to species. (click to enlarge) |
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| Late Flowering Thoroughwort/Boneset, with Clip-winged
grasshopper and Red banded Hairstreak butterfly. (The butterfly is below the grasshopper and viewed edge on.) (click to enlarge) |
SUMMARY OF OBSERVED SPECIES:
Appalachian Turtlehead
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Chelone lyonii
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Bracken Fern
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Pteridium aquilinum ssp. latiusculum
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Bigleaf Magnolia
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Magnolia macrophylla
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American Toad
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Bufo (Anaxyrus) americanus
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Ovate Catchfly
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Silene ovata
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Joro Spider
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Trichonephila clavata.
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Hop hornbeam
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Ostrya virginiana
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Sourwood
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Oxydendrum arboreum
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Possumhaw Holly
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Ilex decidua
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Eastern Fence Lizard
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Sceloporus undulatus
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Musclewood
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Carpinus caroliniana
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Yellow Crownbeard
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Verbesina occidentalis
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Climbing Hempvine
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Mikania scandens
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Smooth Ground Cherry
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Physalis angulata
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River Birch
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Betula nigra
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Northern Red Oak
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Quercus rubra
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Tulip Tree/Yellow Poplar
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Liriodendron tulipifera
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Winged Elm
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Ulmus alata
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Sycamore
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Platanus occidentalis
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Green Ash
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Fraxinus pennsylvanica
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Angle-pod
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Gonolobus
suberosus (= Matelea gonocarpos)
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Late Flowering Thoroughwort/Boneset
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Eupatorium serotinum
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Red-banded Hairstreak
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Calycopis cecrops
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Clip-winged
Grasshopper
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Metaleptea brevicornis
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Silverbell
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Halesia sp.
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Box-elder
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Acer negundo
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