Ramble Report May 11 2017

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:

Southern Lady Fern
form with red rachis

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.

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.

Christmas Fern; note boot-like shape of pinnae

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.

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.

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.

Virginia Rattlesnake Fern; sterile frond

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.

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.

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.

Sensitive Fern

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.

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.

Florida Wood Fern; note the grooved rachis

Florida Wood Fern has a grooved rachis and alternate pinnae.

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.)

Royal Fern fertile frond

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

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.)

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

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.

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.

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.”

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.

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 Lady fern	Athyrium asplenioides (= A. filix-femina)
Jack-in-the-pulpit	Arisaema triphyllum
Christmas fern	Polystichum acrostichoides
Eastern marsh fern	Thelypteris palustris
Cinnamon fern	Osmundastrum cinnamomeum (=Osmunda cinnamomea)
Marginal wood fern	Dryopteris marginalis
Black cohosh	Cimicifuga racemosa (= Actaea racemosa)
Early meadow rue	Thalictrum dioicum
Virginia rattlesnake fern	Botrychium virginianum (= Botrypus virginianum)
Southern maidenhair fern	Adiantum capillus-veneris
Ebony spleenwort	Asplenium platyneuron
Sensitive fern	Onoclea sensibilis
New York fern	Thelypteris noveboracensis
Southern beardtongue	Penstemon australis
Indian pink	Spigelia marilandica
Florida wood fern	Dryopteris ludoviciana
Goldenseal	Hydrastis canadensis
Ground-cedar	Diphasiastrum digitatum
Broad beech fern	Phegopteris hexagonoptera
Royal fern	Osmunda regalis
Fly poison	Amianthium muscitoxicum
Horsetail	Equisetum hyemale
Yucca	Yucca filamentosa
Leaf-footed bug	Leptoglossus phyllopus
Smooth purple coneflower	Echinacea laevigata
Longleaf pine	Pinus palustris
Purple milkweed	Asclepias purpurascens
Southern wild indigo	Baptisia australis
Common elderberry	Sambucus canadensis
Fringed bluestar	Amsonia ciliata