Leader of Today’s Ramble: Linda
Authors of Today’s Report: Linda Chafin, Don Hunter
The photos that appear in this report were taken by Don Hunter unless otherwise credited. Photos may be enlarged by clicking them with a mouse or tapping on your screen. Not all of Don’s photos from today’s ramble made it into the Ramble Report, so be sure to check out his Facebook album at this link.
Nature Ramble Rainy Day Policy: We show up at 9:00am, rain or shine. If it’s raining, we will meet and socialize in the conservatory (bring your own coffee); if there is a break in the rain, we’ll go outside and do a little rambling.
Today’s Emphasis: Warm season grasses
Announcements and other news:
Gary announced a Rivers Alive invasive plant cleanup on October 19th behind Oglethorpe Elementary School where there is a massive infestation of Oriental Bittersweet. Google the Athens River Alive website for details on how to sign up. Spaces are limited.
Sher passed around a laminated, ten-fold Guide to Common Lawn and Garden Weeds of the Southeast, by Michael Homoya. It includes illustrations and descriptions for 60 species of both native and introduced weeds commonly found throughout the southeastern U.S. Sher purchased it in the Bot Garden’s gift shop. It is also available online here.
Gary announced that we are in the middle of the fall bird migration, an annual event that is so massive that the migrating birds can be seen on weather radar. Hawks and water fowl migrate during the day but most songbirds migrate at night to avoid predators and take advantage of better flying conditions. He reported that last night 4.8 million birds passed over Athens/Clarke County. On an average September night, 60 million songbirds fly across the southeast U.S. and 594 million fly across the United States. He quoted from an article, “Night Moves,” on the Audubon Society web page that describes this amazing phenomenon and the new technologies that allow us to virtually witness it.
We talked a bit about the severity of Helene, whose center of circulation – the “eye” – passed directly over Athens/Clarke County, apparently preventing us from receiving the kind of damage experienced in Augusta.
Number of Ramblers Today: 32
Today’s Route: We walked down the entrance road to the White Trail spur trail and out into the right-of-way prairie, then turned right/north into the Nash Prairie. After a while we took a U-turn downhill and walked through the newly created prairie.
Don’s Pre-Ramble Observations:
Japanese Anemone in flower near the Children’s Garden arbor.
Versute Sharpshooter resting on the pink, hairy leaves of a Strap Flower shrub (aka Chinese Fringe Flower and Loropetalum).
Observations:
Before beginning our annual rambler “grass class,” Linda reminded us of some “grass class” basics. Grasses are wind-pollinated, therefore have no need for showy flowers to attract pollinators. Instead, they have flowers that are so small and so reduced that they are called “florets.” One to many florets are held in clusters called spikelets. All the essential parts are there as in typical flowers but they are much reduced in size and complexity and require a strange new vocabulary: glume, lemma, palea, and awn.
River Oats spikelet in flower in May, with 10 florets
Grasses also have distinctive leaves that are divided into two parts, the leaf blade and the leaf sheath. The blade is what we usually refer to when we talk about grass leaves. The
sheath is the lower part of the leaf and it tightly clasps the grass stem, often covering the stem entirely for an inch or more.
At the inner angle where the blade and the sheath meet is a tiny, easily overlooked structure called a ligule. It may be a delicate membrane, or a line of hairs, or a papery fringe, among other types, but it is always present in some form or another and is an important diagnostic feature for many grasses. The function of the ligule is unknown but it may prevent rain and debris from getting down into the leaf sheath.
Grasses come in two growth forms: bunch grasses (all of Georgia’s native grasses) and turf grasses (all of Georgia’s lawn grasses). All of Georgia’s turf grasses are exotic (think: Zoysia, Bermuda, St. Augustine, etc.). Bunch grasses typically have deep roots – in midwestern prairies with deep topsoil, native grass roots may reach six feet deep. In the Piedmont, topsoil was washed into the rivers and down to the coasts two centuries ago. How deeply grass roots can penetrate the clay subsoil we now have varies from site to site and depends on the type of clay and the species of grass. Turf grasses have shallow roots that penetrate only a few inches in any type of soil and contribute little organic matter to the soil.
Bunch grasses grow in bunches, aka tussocks or clumps. The spaces between the clumps are important to small wildlife, providing fallen seeds, travel corridors, and safe nesting sites for many birds, small mammals, and reptiles. Photo credit.
Grasses also have two different flowering times. Grasses that bloom in the spring are known as cool-season grasses; grasses that flower in late summer/fall are called warm-season grasses. Warm-season grasses conduct photosynthesis using a special method (called C4) that minimizes water loss and allows them to be very productive in high temperatures; after flowering, the aboveground parts wither (in our climate). Cool season grasses more or less shut down their growth during the summer and resume growing in the fall when temperatures drop, often remaining green and photosynthetic during our mild winters.
Now widely used in landscaping, Muhly Grass, with its long, flexible leaves, has long been used by Gullah-Geechee basket weavers on the Georgia and South Carolina coast to form the tight knot at the center of each basket. Muhly Grass is sometimes called Sweet Grass, but should not be confused with the northern Sweetgrass (Hierochloe odorata) that is the subject of Robin Wall Kimmerer’s book, Braiding Sweetgrass.
Seed heads of a white-flowered cultivar of the typically pink-flowered Muhly Grass. Both the pink- and white-flowered versions are planted in the Children’s Garden.
Little Bluestem is another native grass planted in the Children’s Garden. Its stems seem to be striped maroon and blue-green. In fact, the stems are maroon and the leaf sheaths that wrap around the stems are blue-green. Though closely related to Big Bluestem and Broomsedge, Little Blue is a much more delicate grass.
Little Bluestem has sparsely flowered but very hairy spikelets. Photo by Steven Severinghaus.
Patches of River Oats are scattered along the White Trail Spur trail we took to the right-of-way. River Oats is actually a cool-season grass that flowers in late May or June, but its spikelets persist well into late fall. The spikelets are large and contain 6-17 florets that have largely turned brown by now. If fertilized, those florets will each produce a single seed. Some people call this species “fish-on-a-pole.”
Unfortunately, patches of Purple Fountain Grass, an invasive ornamental, have persisted in the right-of-way prairie, dating from the perennial beds that were established here decades ago.
Two species of love-grass – Purple Love Grass (above) and Big-top Love Grass (below) – are among my favorite native grasses. Both have large, open, and airy seed heads that catch the dew and glow in the early morning sunlight, below left. In the case of Purple Love Grass, the seed heads are up to 18 inches long and 14 inches wide, with tiny pink-purple spikelets, each packed with 5-15 tightly stacked florets, above. Bigtop has a much larger seed head, up to 34 inches long and 16 inches wide, below, with greenish-white spikelets only slightly tinged with pink; there are only 2-6 tightly stacked florets per Bigtop spikelet. Both of these lovegrass species are “tumbleweeds”: when the seeds are mature, the stem dries and breaks off at ground level, and the seed head tumbles across the landscape, spreading its seeds.
Purple Top or Greasy Grass is named for the dark purple spikelets which are coated with wax that prevents them from drying out. The spikelets matured early this year due to the drought and are brown and not very “greasy.” Purple Top can be recognized at
55 mph – its seed head is triangular in outline and composed of delicate, gracefully drooping or arching branches.
Broomsedge may be the most common native grass in Georgia, blanketing abandoned fields and pastures and turning a beautiful coppery color in the winter.
A large bract – called a spathe – encloses Broomsedge spikelets till they are ready to shed their seeds. As the tufted seeds emerge from the spathe, they are caught and carried by the wind. Ramblers asked why Broomsedge is so ubiquitous in the Piedmont: a partial answer is that each plant produces up to 200 seeds per year.
Broomsedge often grows with Split-beard Bluestem, below, a similar grass in the same genus, Andropogon (literally, man beard). From a distance, they look much the same and both turn copper-colored in the winter.
Up close, you can see important differences between Broomsedge and Splitbeard. Splitbeard spikelets are not enclosed in a spathe but are instead on a pair of short branches at the top of a relatively slender, leafless stalk – the branches start out as a single unit (left), then split in two as they mature (center), and finally look like worn-out paintbrushes after the seeds are dispersed.
Smutgrass is a common but inconspicuous grass, especially when it lacks the fungal smut (Bipolaris sp.) that usually blackens the seed head (below) and upper leaves.
Beaked Panic Grass spikelets abruptly taper to a tiny bird’s beak. Until recently, this species was in the genus Panicum and, despite being moved to the genus Coleataenia, keeps the “panic” in its common name. The “panic” in panic grass derives not from the anxiety provoked in botanists when confronted with plants in this genus but from the Latin root “pānis,” meaning bread, suggesting that the seeds of some panic grasses were dried and ground into a flour.
With its eight-foot tall stalks, Silver Plume Grass is the most conspicuous grass in the Nash Prairie. The seed head goes through several stages on its way to seed dispersal, beginning as a flattened, fan-shaped silvery-pink plume in September that narrows and turns tan as the florets mature, then explodes into a large silvery-tan plume loaded with hundreds of seeds, below, left. Each seed is tipped with hairs and a long, twisted bristle that give the plume a woolly look, right.
Two other large grass species are conspicuous in the right-of-way prairie:
Big Bluestem and Yellow Indian Grass.
Yellow Indian Grass seed heads are
a beautiful golden yellow. Each seed is tipped with a bristle that is bent ninety
degrees and “corkscrews” the seed into the ground as the bristle twists in
response to changes in humidity. The blueish-greeb leaves have an unusual ligule (below) at the junction of
sheath and blade that resembles a pair of upright terrier ears.
A type of smut fungus, Sporisorium ellisii is a parasitic fungus that infects members of the Broomsedge/Bluestem genus of grasses. It infects the reproductive parts of the plant, rendering them sterile.
Big Bluestem stems often reach 10 feet in height and are topped with a large branched seed head sometimes called a “turkey foot,” below (photo credit).
Don’s close-up photo of one of the Big Blue branches spotlights the yellow, dangling anthers and brushy, pink styles.
Perennial Foxtail Grass (aka Knotroot Bristle-grass) is a relatively small and delicate native grass (photo, left). Its spikelike seed heads consist of tightly packed spikelets each of which is surrounded by white bristles, creating the foxtail effect. Yellow Foxtail Grass (right) has recently shown up on roadsides in Clarke County – it’s a European species that is clearly becoming invasive. Its stems are taller and coarser than our native Foxtail and its seed heads are larger too, with yellow or tan bristles.
The early fall wildflowers – boneset, ironweed, sunflowers, and beans – are past or nearly so at the Garden. The last of the fall wildflowers are still in bloom, though, including Calico Aster. With its white ray flowers and yellow disk flowers, this species resembles three other bushy fall-flowering asters. All four have stiff, almost woody stems and many tiny leaves interspersed with a few larger leaves. The disk flowers turn red after they are pollinated; bees lack a photoreceptor for the color red and do not see these red flowers. Both the plant and the bee benefit when bees focus their efforts on yellow, unpollinated flowers that are still producing nectar.
Blue Curls flowers along the White Trail spur
The “curls” refer to the four stamens and single style that emerge from the top of the flower, perfectly placed to receive and deposit pollen on the backs of visiting bees.
Coastal Dog-fennel (aka Yankeeweed), below, is close kin to the common Dog-fennel that grows throughout the right-of-way. This is our first sighting of this species at the Garden; perhaps it was brought in on the tire treads of Georgia Power equipment from a work site in the Coastal Plain. Dog-fennel leaves are divided into thread-like segments about 1 mm wide; Coastal Dog-fennel leaves are divided into somewhat wider segments 2-5 mm wide.
Red-root Flatsedge – a sedge not a grass – is typically found in wetlands but is thriving in a low spot at the base of the slope of the powerline prairie. Each of the slender, pointed structures is a spikelet that contains 6-30 seeds.
The large Loblolly Pines on the western edge of the powerline prairie support several large vines of Trumpet Creeper, Poison Ivy, and Virginia Creeper. Bill spotted the caterpillar (below, left) of a Poison Ivy Leaf-miner Moth on a Poison Ivy leaflet and a Trumpet Vine Moth caterpillar (center) in one of the fruit pods hanging on the Trumpet Creeper. A Trumpet Vine Moth adult (right) coincidentally showed up later at Bill’s porch light. (All three photos by Bill Sheehan)
SUMMARY OF OBSERVED SPECIES
Daddy Longlegs Family Opiliones
Japanese Anemone Anemone hupehensis var. japonica
Versute Sharpshooter Graphocephala versuta
Red Strap Flower Loropetalum chinense var. rubrum
Muhly Grass Muhlenbergia capillaris
Little Bluestem Schizachyrium scoparium
River Oats Chasmanthium latifolium
Gulf Fritillary butterfly Agraulis vanillae
Purple Fountain Grass Pennisetum setaceum ‘Rubrum’
Blue Curls Trichostema dichotomum
Purple Lovegrass Eragrostis spectabilis
Bigtop Lovegrass Eragrostis hirsuta
Purpletop Grease/Greasy Grass Tridens flavus
Broomsedge Andropogon virginicus
Splitbeard Bluestem Andropogon ternarius
Smutgrass Sporobolus indicus
Beaked Panicgrass Panicum anceps (synonym Coleataenia anceps)
Silver Plume Grass Erianthus alopecuroides
Yellow Indian Grass Sorghastrum nutans
A smut fungus (Yellow Indian Grass) Sporisorium ellisii
Big Bluestem Andropogon gerardii
Perennial Foxtail Grass Setaria parviflora (synonym Setaria geniculata)
Yellow Foxtail Grass Setaria pumila
Calico Aster Symphyotrichum lateriflorum
Coastal Dog Fennel Eupatorium compositifolium
Dogfennel Eupatorium capillifolium
Vasey Grass Paspalum urvillei
Red-root Flatsedge Cyperus erythrorhizos
Trumpet Creeper Campsis radicans
Poison Ivy Toxicodendron radicans
Virginia Creeper Parthenocissus quinquefolia
Trumpet Vine Moth (larva) Clydonopteron sacculana
Poison Ivy Leaf-miner Moth (larva) Cameraria guttifinitella
Ailanthus Webworm Moth Atteva aurea