Today's Ramble was led by Dale Hoyt.
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 Dale Hoyt with assistance from Linda Chafin.
Today’s Focus:
Orange Trail, from the Orange Spur bridge to the parking lot
18 Ramblers met today.
A pre-Ramble treat: As we gathered in the Plaza, hundreds of Cedar Waxwings erupted from the nearby holly trees, milled about, flying back and forth over the Plaza, and suddenly departed.
Today’s reading was a short piece
pertinent to the season:
Gazing in the distance you will now see a long-awaited green
mist, the stirring of tree leaves emerging from their buds. Soon we will be
able to hear them rustling in the wind and this soft sound signals a change in
the short life of the ephemeral flowers on the ground below. The closing of the
canopy deprives them of sunlight and they must rush to produce their fruits and
seeds and then retire until next spring.
Dale Hoyt, April, 2014
Announcements:
1.
Next week
the Ramble will be at Rock and Shoals Natural Area. Because parking there
is limited, we will need to car pool. Meet at the Botanical Garden parking lot
(near the Bus Stop shelter) at 9:00 A.M. and we will organize the car pools, 5
persons per car, then drive out to the Rock & Shoals. Please be on time!!! Stragglers will be left behind!!! We will
return at approximately 12:00 – 12:30 p.m.
2.
Halley said she has plenty of young shrubs and Painted Buckeye to give
away...just come by to get them.
3.
Dr. Ali invited all the Ramblers to the Open House at the
Al-Huda Islamic Center, on Saturday, April 13, 2019, from 2 p.m. to 6 p.m.
4.
Weds., April 17, 2019, Cine will screen a
special showing of Hidden Rivers of Southern Appalachia. Reception (catered by
The National) and Exhibit at 6:30, followed by screening and discussion at
7:30. Tickets are $5 per person and are available at the Ciné box office [or online at http://athenscine.com/movie/hidden-rivers].
Today's route:
Through the Conservatory to the Orange Trail Spur. Down the spur trail to the
Orange Trail and left on the Orange Trail to the parking lot.
OBSERVATIONS:
Past the statue, on the asphalt
path approaching the gate to the Orange Spur Trail there are plantings of several
native wildflowers. Currently there are only two in bloom:
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| Dwarf Crested Iris |
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| Green and Gold |
Orange Trail Spur:
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| Yellow Three-parted Violets were seen all along the spur trail. |
On our Ramble two weeks ago Don
found the emergent leaves of Carolina Lilies. They were still here today and,
with luck, will not be discovered by deer.
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| Mayapples; two weeks ago they were strongly mottled. |
At the turn of the path
above the bridge there is a group of Mayapples we first saw on our March 21
Ramble. Then they were strongly mottled with darker green areas around the
margins of the leaves. Today that mottling is far less obvious and many of the
plants are infected with the Mayapple Rust fungus.
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| Orange patches on the undersurface of a Mayapple leaf Mayapple Rust fungus |
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| Enlarged view of Mayapple Rust; the red-orange circular cups produce spores which will infect other plants. |
The granular orange patches
on the undersurface of the leaf are produced by the rust fungus. They are where
the rust spores are produced and released. (Rusts are important pathogens of
plants and many rust species have complex life cycles that involve two or more
host plant species. The Mayapple Rust appears to have a simple life cycle that
does not require any alternate hosts.
 |
| As the infection progresses it becomes visible on the upper leaf surface. |
As the season progresses the
effect of the rust infection becomes obvious on the top of the leaf: yellow
spots appear where the rust is feeding on the leaf.
Each Mayapple plant produces
a single leaf per stem, except when the plant can flower. Then the stem forks
about 6 inches above the ground and each branch produces a sing leaf.
The
flower bud appears at the fork. Two weeks ago we saw several plants with buds
and today the beautiful white flowers are open. If pollinated, they will
produce a fruit about the size of a lemon.
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| Flower of Mayapple |
All parts of the Mayapple are poisonous, except the ripe fruit. (The unripe
fruit and the seeds are poisonous.) Box Turtles are known to eat the fruit and,
as a consequence, disperse the contained seeds when they defecate.
The poison is podophylline and
was once evaluated as a chemotherapeutic agent for the treatment of cancer. It
proved to have too many side-effects and was abandoned.
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| American Beech twig with sharp, pointed buds and last years leaf still hanging on. |
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| Freshly opened American Beech leaves; you can still see the remains of the bud scales that protected the shoot and its leaves during winter. (photo by Emily Carr) |
Only a few of the young Beech
trees have started to leaf out. As the shoot within a leaf bud becomes active
the buds swell and the bud scales separate and fall away. The shoot grows
mainly by increasing the length of each cell, not by increasing the number of
cells. This means that the embryonic shoot was actually formed in the previous
year. All the new spring growth is caused by cells absorbing water and
swelling, the direction of growth controlled by how the cell walls are
synthesized.
Orange Trail
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| Rue Anemone was growing up and down the Orange Trail |
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| Leaves of Little Brown Jug, AKA Heartleaf |
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| Flowers of Little Brown Jug (covering leaf litter removed) (Photo by Emily Carr) |
The flowers of Little Brown Jug are
unusual as they are found beneath several layers of leaves. If the purpose of a
flower is to attract pollinators, why are these buried in leaves, out of sight
of birds, butterflies and hummingbirds. It is hard to determine what the
natural pollinators of such plants are. Normally you could sit and count visits
by bees or other insects, but in this situation you can’t see the flowers. And
if you remove the leaf litter you may discourage the natural pollinators from
coming. Other strategies must be used. Emasculating the flowers by removing the
stamens results in no seed set, suggesting that pollinators are not carrying pollen
from other plants. That means that if pollinators are present they probably carry
pollen from stamens to pistils within the same plant. This subject needs
further investigation.
(Note: The common or vernacular
name of this species has seen almost as many changes as the botanical name.
Other names: Heartleaf, Wild Ginger, Heartleaf Wild Ginger. Wild Ginger is especially
troublesome because Asarum canadense is also called Wild Ginger. I would prefer
to call it Little Brown Jug, a reference to the size and shape of its flowers,
just because that is a unique name, unlikely to be given to another plant.
YOMV.)
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| Wild Geranium |
Wild Geranium is currently blooming and we
found many plants along the trail. This species has two kinds of flowers: those
that have both stamens and pistils (perfect flowers), and those that lack stamens completely (pistilate flowers).
(Remember: the stamens produce pollen, the pistil holds the egg that develops into the seed.) This condition, where a species has two types of flowers, perfect or female, is
called “gynodioecious” (pronounced: Gy-no-dye-E-shus). (Note that this term applies
to the population or species, not the individual plant or flower.)
Gynodioecy may be a stepping
stone on the way to evolving into a species in which there are only two kinds
of plants, those with male flowers and those with female flowers. That
condition is called dioecious (pronounced: dye-E-shus).
Plants have two ways of passing
their genes on to the next generation: via seeds or pollen. If a plant loses
the ability to produce pollen you would think that it would lose the
evolutionary race to those that produce both. But making pollen takes energy
and a plant that doesn’t have to make pollen can use that energy to make more
or larger seeds. That could give it an advantage over the other plants with
perfect flowers.
So, imagine that more and more
of the plants in a population become female only and the number of perfect flowered
plants declines. Eventually the population will reach a point where there are
only a few plants with stamens and there is not enough pollen to fertilize all
the potential seeds. Now the plants that are producing pollen have the
evolutionary upper hand and they will start to increase. It would seem to be
pretty difficult to evolve into a dioecious species from a gynodioecious one.
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| The tiny purple and yellow flowers of Yellowroot. |
A Yellowroot
shrub has been growing next to a stream-side boulder since the first Nature Ramble in 2011 and certainly before that time.
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| Huger's Carrion Flower |
When most of us think
of Smilax (and most of us don’t, usually), we think of the high-climbing, spiny
vines called catbrier or greenbriar. Few people are aware that there are four
species of herbaceous, spineless Smilax that grow throughout Georgia. The one
growing along the Orange Trail is Smilax hugeri, also known as Huger’s
Carrion-flower. Its small, green flowers are held in round clusters at the top
of the short stems and have a foul odor (hence the common name) that attracts
pollinating flies and gnats.
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| Common Blue Violet |
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| A cleistogamous flower of Common Blue Violet |
At one of the small foot
bridge crossings, we saw a huge cluster of Common Blue Violets. Violets have
two ways of producing seeds: 1) from the conspicuous flowers that attract
insect pollinators or 2) from flower buds that grow lower in the plant and
never open. In the latter the seeds are produced by self-fertilization. The
formal term for such flowers is “cleistogamous,” from the Greek, meaning
“closed marriage.”
Cleistogamous flowers are not
unusual, they occur in many plants, and are thought to provide reproductive
assurance in the event that the “regular” flowers fail to produce seeds.
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| Solomon's Seal |
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| Solomon's Plume |
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| Newly emerged Broad Beech fern |
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| Mature Broad Beech fern, oriented so you can see the "fox's face." The tip of the frond is the nose and the two ears at the other end of the frond. |
Most of the Broad Beech ferns
have recently emerged from the ground and have not fully expanded their fronds.
The two basal pinnules form a V-shape that makes this fern easy to identify. If
you imagine those pinnules as ears and the rest of the frond as a narrow snout,
you’re looking at a fox’s face. (You have to turn you head to see the face with
ears up and the nose down.)
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| Sycamore root, exposed by erosion |
Gary pointed out the roots
of an American Sycamore that were growing out of the bank and across the rocks
in the stream. They had the same,
blotchy pattern as the newer bark on the tree.
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| Adult CaddisflySource: David Short from Windsor, UK [CC BY 2.0] |
Most people have seen insects
called caddisflies without knowing it. They are attracted to lights and you
probably thought they were drab little moths. But their wings are covered with
hairs rather than scales. Like moths, they have larvae that look like
caterpillars, but caddisfly larvae are aquatic, living in ponds, lakes, streams
and rivers, where they mostly eat algae or decaying vegetation that they scrape
off submerged objects. Many species make cases out of objects they find in
their habitat: sand grains, small pebbles, small sticks, bits of plant
material. The material is fashioned into a tube held together by silk spun from
glands in the larva’s mouth. These cases protect them from predators like fish.
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| Hooked Buttercup |
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| Closeup of Hooked Buttercup The name comes from the hooks on the pistils. |
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| Spreading Wood Rush |
We saw both Kidneyleaf
Buttercup and Hooked Buttercup at the edge of the stream. Nearby were some Spreading Wood Rushes
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| Rattlesnake Fern (Photo by Emily Carr) |
Rattlesnake Fern is just
emerging. Many ferns produce spores from structures on the lower surface of
their leaves, while other species devote entire fertile fronds that bear the
spore-producing structures. Over the next few weeks the Rattlesnake fern will
send up a fertile frond from among the leafy, sterile fronds that we saw today.
To some eyes, this looks like the tail of a snake sticking up from coils of
greenery, suggestive of a coiled snake. (A good imagination helps, here.)
SUMMARY OF OBSERVED SPECIES:
Cedar Waxwing
|
Bombycilla cedrorum
|
Dwarf Crested Iris
|
Iris cristata
|
Green-and-Gold
|
Chrysogonum
virginianum
|
Yellow Three-parted
Violet
|
Viola tripartita
|
Carolina Lily
|
Lilium michauxii
|
Mayapple
|
Podophyllum peltatum
|
Mayapple Rust
|
Allodus podophylli
|
American Beech
|
Fagus grandifolia
|
Rue Anemone
|
Thalictrum
thalictroides
|
Little Brown Jug
|
Hexastylis arifolia
|
Wild (Spotted) Geranium
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Geranium maculatum
|
Common Blue Violet
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Viola sororia
|
Walter's Violet?
|
Viola walteri
|
Yellowroot
|
Xanthorhiza
simplicissima
|
Huger’s Carrion Flower
|
Smilax hugeri
|
Solomon's Seal
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Polygonatum odoratum
|
Solomon's Plume
|
Maianthemum racemosum
|
Chickweed
|
Stellaria media
|
Broad Beech Fern
|
Phegopteris hexagonoptera
|
American Sycamore
|
Platanus occidentalis
|
Caddisfly (case)
|
Insecta, Class
Trichoptera
|
Kidneyleaf Buttercup
|
Ranunculus abortivus
|
Hooked Buttercup
|
Ranunculus recurvatus
|
Spreading Wood Rush
|
Luzula echinata
|
Rattlesnake Fern
|
Botrypus virginianus
|
