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.)
Today’s post was written by Linda Chafin and Don Hunter.
Twenty Ramblers met today.
Announcements:
Saturday, May 13, at 10:00AM:
Natural History of the Scull Shoals Historic Site and the
Durham Herb Walk – Geology, Hydrology and Plant Life
A walk guided by our own Don Hunter. You can learn more about the
historical significance of Scull Shoals at the Friends of Scull Shoals website. Directions: From Athens
drive south to Watkinsville; take GA15 south out of Watkinsville for about 19
miles to Macedonia Rd. Turn left on Macedonia Rd. and travel
approximately 2.4 miles to Forest Service Rd 1234 (gravel road) on the left.
Turn left onto a gravel road and travel approximately 2 miles to Scull Shoals
Historic Site.
Wednesday, May 17, at 5:30PM: Greenway Expansion
Celebration
A free Ice Cream social to
celebrate the expansion of the ACC Greenway. Click here for
more information.
Saturday, May 20, 12-2 PM: Annual Meeting of the Friends of
the Georgia Museum of Natural
History, GMNH Annex, 4435 Atlanta Highway, Athens
Ramblers
and friends are welcome!
Free
refreshments, music and opportunity to see the research collections!
Today’s reading:
Bob Ambrose recited one of his latest poems – inspired by plate tectonics. You
can read it in this week’s Ramble Report email.
Today’s route:
Through the Shade Garden via the cement walkway to the Dunson Native Flora
Garden. Then through the DNFG, exiting at the bottom near the Yucca planting
and returning via the road.
Today’s emphasis was on ferns.
Parts and Pieces
of Ferns
The entire leaf of a fern (from ground level to tip) is
called a frond.
The stalk is called a stipe. Where the stipe extends up into the blade, it is called a rachis.
The leafy part of the frond is called the blade.
The blade is usually divided into many leaflets called pinnae. If the pinnae are subdivided,
the sub-leaflets are called pinnules.
When fern fronds unfurl in the spring, they typically
emerge as fiddleheads, which are
also called croziers (which Avis
pointed out, is the name for a shepherd’s crook).
Fern stems in our area are underground and are called rhizomes or rootstocks.
Most ferns have spore-producing structures (sori) on the undersides of their leaves
– they may be round, kidney-shaped, crescent-shaped, and so on. A few ferns
produce spores on separate fronds that are no longer primarily photosynthetic
but are modified to be spore-producers. More about this later.
Ferns in the
Garden today:
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| Southern Lady Fern form with red rachis |
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|
| Southern Lady Fern form with green rachis |
Southern Lady fern,
which has rectangular pinnae that abruptly taper to pointed tips (acuminate). Lowland examples have red stems (stipes) with scattered scales
but no hairs – because “southern ladies always shave their legs.” (Thanks to Atlanta botanist, Steve Bowling, who
taught me the funny mnemonics!) The Dunson Garden has two variations of Southern Lady Fern, one with the red
rachis and stipe is found at lower elevations in Georgia. The other, found at
higher elevations, has a green rachis and stipe. They both have acuminate tips
on the pinnae.
Tim brought up the two
growth patterns for ferns in our area – either clumps or patches – which
are determined by the position of their rhizomes. If the rhizome is erect, the
fronds emerge from its tip in a clump or rosette, usually forming a vase- or
fountain-like shape. If the rhizome creeps along horizontally underground,
fronds will emerge from buds scattered along its length, forming a patch of
fronds, which may be either dense or loosely scattered. Examples of
clump-formers include Christmas Fern and Cinnamon Fern. Patch-formers include
New York Fern and Hay-scented Fern.
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|
| Marsh Fern |
We stopped to look at a large clump of Marsh Fern, and Linda passed around a
marsh fern frond tip, where the spore-producing structures (sori) were visible on the underside. Sori
differ quite a bit from species to species and can be used to identify ferns to
species.
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|
| Christmas Fern; note boot-like shape of pinnae |
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|
| Sori of Christmas Fern |
Christmas fern
is one of a handful of evergreen ferns in our area. Their dark green, leathery
fronds were used for Christmas decorations back in the day, hence the name.
Also, the individual pinnae are shaped somewhat like Christmas stockings. The
sori are crowded together in brown masses on the undersurfaces of only the
upper third of the pinnae. This is an example of a fern that doesn’t follow the
typical pattern of having sori on all the pinnae.
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|
| Cinnamon Fern; note the “hairy armpits” |
A small example of Cinnamon
Fern is growing at the entrance to Dunson Native Flora Garden. Linda
pointed out the small patches of fuzzy, white hairs at the base of each pinna
on the underside of the frond. These “hairy armpits” (thanks again, Steve!) are
diagnostic for Cinnamon Fern. We didn’t see any fertile Cinnamon Fern fronds
today, and it’s possible they may have come and gone already. When present,
they are quite showy – a bright, rusty orange frond rising from the center of
the clump. Because the spores are produced only on this fertile frond, you will
never see any sori on the lower surfaces of Cinnamon Fern fronds.
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|
| Marginal Wood Fern; note sori toward the edge (margin) of the pinnules |
Next to the Cinnamon Fern is a Marginal Wood Fern, which is distinguished by the round,
spore-producing sori that line the margins of the pinnules. We also examined
last year’s fronds which were decaying around the base of the plant. Marginal
Wood Fern fronds overwinter by spreading their fronds flat against the ground.
This allows maximum exposure to sunlight during the winter. They disintegrate
as new fronds begin to emerge in the spring.
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| Virginia Rattlesnake Fern; sterile frond |
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||
| Virginia Rattlesnake Fern; fertile frond |
Angeli pointed out a Virginia
Rattlesnake Fern, which is an indicator of moist, rich soils. Virginia
Rattlesnake Ferns have only one large, triangular blade per plant; it is
divided into three triangular pinnae (each of which actually look like blades) that
are in turn also divided and subdivided, giving the overall frond a very lacy look.
Visible on all the Rattlesnake Ferns we saw today were the tan, narrow, erect,
fertile stalks which arise from the base of the blade and are devoted to
producing spores.
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|
| Southern Maidenhair Fern |
A small patch of Southern
Maidenhair Fern grows along the creek bank. Like Northern Maidenhair Fern,
it has black, wiry stems, but the blade is triangular and typically drooping. Naturally,
it occurs in areas with limestone or other high pH bedrock; in Georgia, largely
in southwest Georgia. Northern maidenhair
has a fan-shaped or semi-circular blade, with several black rachises
fanning out from the top of the erect, black stem. Each rachis holds numerous
soft, blue-green pinnules.
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|
| Ebony Spleenwort |
Next to the Southern Maidenhair was Ebony Spleenwort, also with a black stem but not resembling the
Maidenhairs in any other way. It grows in a small clump, with fronds arising
from a short rhizome. It is found in nearly every county in Georgia and can
grow in a variety of environments. It’s the only fern you’ll see in the dry,
heavy clays of old cotton fields.
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|
| Sensitive Fern |
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| Sensitive Fern with eaten frond |
Working our way across the Dunson Garden, we stopped at a
patch of Sensitive Fern, with its
large undivided pinnae and winged rachis. It gets its name because it is cold-sensitive.
Dale was amazed that many of the fronds had been heavily grazed by insects,
some nearly completely consumed. Most ferns have a natural, chemical protection
against grazing by herbivores or insects that might eat and damage the leafy
parts of the plant. But the website illinoiswildflowers.com clued us in that
larvae of the sawfly Hemitaxonus
dubitatus do feed on the fronds but, not having seen the culprit today, we
don’t know if that is the insect responsible for the damage we saw. [That sawfly
species is also only known from Michigan and the NE states, but these insects
are not well studied and it is possible that it, or a related form, occurs here
in Georgia. DH] Dale points out that sawflies aren’t flies — they’re
Hymenopterans, related to wasps, bees, and ants (gotta love those common
names!).
Sensitive Fern is yet another example of a fern that
didn’t get the “fern spore-placement memo.” Its spores are produced in separate
“fertile fronds” that arise from the
widely spreading rhizomes several inches from the green, sterile fronds. The brown,
bead-like structures clustered at the top of the fertile frond will open to
release thousands of tiny spores. We saw several fertile fronds that had
persisted through the winter.
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|
| New York Fern |
We next stopped at a patch of New York Fern. It is easily identified because the lacy fronds are
widest in the middle, narrowing towards both the base and the tip of the frond,
because…wait for it. “New Yorkers burn their candles at both ends.” (Another Steve Bowling-ism!) They are patch-formers
and sometimes entirely cloak large slopes in the mountains with their pale, lime-colored
green fronds. Tim mentioned that New York Fern contains a natural insecticide
and will form large patches, overtaking some hillsides. Only one insect is
known to feed on its fronds, the caterpillar of Pink-Shaded Fern Moth (Callopistria mollissima), a widespread
species in the eastern US.
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|
| Florida Wood Fern; note the grooved rachis |
Florida Wood Fern
has a grooved rachis and alternate pinnae.
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|
| Broad Beech Fern |
Broad Beech Fern
is another distinctive and easy to identify fern. The lowest pinnae are angled
back, in a swept wing fashion. Avis says its triangular blade resembles a fox’s
face, with the backswept pinnae looking like the fox’s ears. (You have to view
the plant upside down to see the similarity.)
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|
| Royal Fern fertile frond |
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| Royal Fern sterile fronds |
Nearing the wetlands, we found a Royal Fern. A close relative of Cinnamon Fern, its spores are also
produced in an unusual way–on separate fertile pinnae held at the top of the
frond above the green, sterile pinnae.
Other
spore-producing plants
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|
| Running-cedar |
Someone pointed out the Running-cedar or Ground-cedar
growing at the base of the hillside. Linda mentioned that it is one of the clubmosses, a group of primitive plants
living today that flourished during the Coal Age and comprise much of the coal
we burn today. Clubmosses have long been lumped in with ferns since they are
both “seedless vascular plants,” but they are sufficiently different from ferns
to be placed in a different phylum. (Clubmosses are not true mosses.)
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| Horsetails (Scouring Rush) |
Across the little wetland at the west end of the Dunson
Garden, is a large patch of Horsetails.
They are also called scouring rushes because the high silica content makes them
useful for scouring in the absence of Brillo pads (but they are not rushes!).
Horsetails are another group of primitive, seedless vascular plants that were
abundant in the Coal Age, when they were tree-sized. The genus that Horsetails
belong to, Equisetum, has persisted
unchanged since the Carboniferous Period (300-360 million years ago) and is
therefore believed to be the oldest surviving genus of plants on Earth.
Flowering plants
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|
| Jack in the Pulpit this variety has four or five leaflets |
Linda pointed out a small group of four- and five-leaved Jack-in-the-pulpits with no “Jacks”. This
scientific name for this species is Arisaema
triphyllum, meaning “three-leaved,” so plants with four or five leaves are
anomalous. Some botanists treat this form as a separate southern-ranging
species, Arisaema quinata
(“five-leaved”), in part because it is diploid (with the typical two sets of
chromosomes) while Arisaema triphyllum
is tetraploid, with four sets of chromosomes.
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|
| Black Cohosh getting ready to flower |
We stopped to look at several of the many Black Cohosh,
rising up above everything else in the Dunson Garden. Linda likened their
flowering stalks to living candelabras, with their white flower spikes rising
from branches. They will be flowering in the next several weeks.
As we passed by the Goldenseal, we noticed quite a few of
them had green berry-like fruit on a short stem atop the plant. The fruit will
eventually turn red, looking somewhat like a raspberry.
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|
| Indian Pink |
Even though
spring ephemerals are through for the year, we did see a bit of flower color,
including several southern beardtongues, seen growing between the path and the
road. Also, Indian Pink, with its startlingly red-and-yellow flowers, is in
bloom. Linda thinks this plant would be better named “Firecracker Flower.”
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|
| Fly Poison |
We were
surprised to see Fly Poison in flower. A member of the broadly defined Lily
family, its leaves were thought to kill flies and were spread around homes. All
parts of the plant are poisonous, with a high alkaloid content, and the bulb is
especially toxic.
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|
| Purple Milkweed |
In the sunny,
lowest part of the Dunson Garden, we saw Curly-leaf Yucca (with leaf-footed bugs
hanging out on the developing flower buds), Smooth Purple Coneflower and Fringed
Blue-star in early flower, Longleaf Pine (in rocket stage), Purple Milkweed (a
state-listed species), Southern Wild Indigo (our only wild indigo with blue
flowers), and the very large specimen of common elderberry in full bloom.
SUMMARY OF
OBSERVED SPECIES:
|
Southern |
Athyrium (= A. filix-femina) |
|
Jack-in-the-pulpit |
Arisaema |
|
Christmas |
Polystichum |
|
Eastern |
Thelypteris |
|
Cinnamon |
Osmundastrum (=Osmunda cinnamomea) |
|
Marginal |
Dryopteris |
|
Black |
Cimicifuga racemosa (= Actaea racemosa) |
|
Early |
Thalictrum |
|
Virginia |
Botrychium (= Botrypus virginianum) |
|
Southern |
Adiantum |
|
Ebony |
Asplenium |
|
Sensitive |
Onoclea |
|
New York |
Thelypteris |
|
Southern |
Penstemon |
|
Indian |
Spigelia |
|
Florida |
Dryopteris |
|
Goldenseal |
Hydrastis |
|
Ground-cedar |
Diphasiastrum |
|
Broad |
Phegopteris |
|
Royal |
Osmunda |
|
Fly |
Amianthium |
|
Horsetail |
Equisetum |
|
Yucca |
Yucca |
|
Leaf-footed |
Leptoglossus |
|
Smooth |
Echinacea |
|
Longleaf |
Pinus |
|
Purple |
Asclepias |
|
Southern |
Baptisia |
|
Common |
Sambucus |
|
Fringed |
Amsonia |