Friday, October 14, 2016

Ramble Report October 13 2016

Today's Ramble was lead 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 Don Hunter and Linda Chafin, with minor edits/additions by Dale Hoyt.


Visit this page to see the current Announcements.

Today's reading: Dale read a short piece about the Ginkgo tree, inspired by a tree he knew in Indiana. In the morning after the first hard freeze, when the first rays of the sun fell on the tree, all the leaves suddenly started dropping. Within an hour or two most of the leaves had fallen and the ground beneath the tree was covered to a depth of two-three inches with lemon yellow fans.

Ginkgo leaves beginning to turn yellow
 Autumn has an abundance of dreary, drizzly days when everything is drained of color and the chill penetrates to the bone. On such days it’s difficult not to be depressed and the gray sky just reinforces that absence of cheer. But fortunately there is one joy that overcast skies cannot diminish: the Ginkgo tree. As fall begins the Ginkgo starts to absorb all the green from its fan-shaped leaves. They become yellow at their base and the border between green and yellow gradually advances to the edge of the fan, as if all the green is being inhaled into the tree itself. Then the tree seems to hold its breath, as if waiting for some sign. When that mysterious signal arrives the tree suddenly exhales and all the lemon colored leaves cascade to the ground within a few hours. If you’re lucky enough to be standing under a Ginkgo at that very moment you can experience the joy of their soft pelting, summer sunlight and air made palpable, as in their twisting descent they brush against your head and hands, casting your shadow on the earth beneath. Their brilliant yellow defies the drab autumnal sky and, for a moment, you can imagine you see the sun reflected in the pooled leaves beneath the naked branches above.

Dale Hoyt
November, 2012

Today's route: Starting at the bottom of the Dunson Garden we walked over to the power line right-of-way; then up the hill nearly to the top. We returned via the White trail and the Shade garden.
Our focus today was on grasses. Each year Linda teaches a class on Warm Season Grasses of the Georgia Piedmont for the Certificate in Native Plants program. Anyone can sign up for the program; you don't have to be in the Native Plants program (but you might want to be).

Linda's list of warm season grasses that includes most that we saw today can be downloaded from this location. The list includes common and scientific names and brief information on identification and ecology.

Grasslands are found on all the continents of the world and make up from 25-40% of the land surface. Each continent has their own name for grass-dominated ecosystems: prairie in North America, steppe in Eurasia, savannah and veld in Africa, pampas in South America, to say nothing about the coastal marshes dominated by Spartina grass. The major crops that feed the world (directly or indirectly as feed for animals) are grasses: rice, corn, wheat, sugar cane, oats, rye, barley, sorghum and millet. Grasses make up 70% of the world's agricultural land and it is estimated that 50% of the calories consumed by humans are derived from grasses. (Don't forget that a lot of table sugar comes from Sugar cane, and high-fructose corn syrup is found in many processed products.) In the United States many of the calories consumed by our automobiles come from ethanol, a fermentation product of corn seed.

Switch grass florets
There is a large clump of Switch grass at the bottom of the Dunson Native Flora Garden. We stopped to try to understand the basic form of grass flowers. Grass flowers are not showy like most other flowering plants. Because they are wind pollinated, they don't need the showy flower structures, like petals and sepals, to attract pollinators. Switch grass has the most minimalist of grass flowers. It has just one seed-bearing structure or floret per little branch. What we call flower clusters on flowering plants are called spikelets in grasses. What we call sepals in flowers are called lemmas in grasses. What are called petals in flowers are called paleas in grasses. The floret is made up of a lemma and palea, arranged like two praying hands. The palea is a tiny, delicate structure folded into the lemma. The real business parts of the flower – the pistil (consisting of one ovary, styles, and stigmas) and stamens – are found inside the lemma and the palea. At blooming time, they emerge, the stamens to release pollen to the wind and the brush-like stigmas to comb the airborne pollen from the wind. Individual grass flowers are inconspicuous but when massed can be very showy and beautiful. The switch grass clumps in the Dunson garden are the typical size of this species when it occurs in its native habitats. There are smaller switch grass plants in other parts of the Garden but these are cultivars selected to be smaller for the typical home landscape.
Grasses fall into two categories: bunch grasses and the turf- or sod-forming grasses. Bunch grasses form small or large clumps, which can consist of a few to dozens of stems. Most lawn grasses are not bunch grasses, but are turf grasses, forming dense, spreading mats. Bunch grasses are much better for wildlife, with open protected areas of bare soil between the bunches that are used by small mammals, reptiles, and ground nesting birds as avenues of movement within the habitat, and are a good places to nest and browse for food in the form of grass seeds and small insects. Turf-forming grasses, with their dense, homogeneous mats, are virtual deserts with respect to wildlife. Bunch grasses also have really deep root systems and are usually drought tolerant. Turf grasses have shallow root systems that reach down about six inches, often less.
Crab grass spikelets

Dallis grass spikelet
Bermuda grass
On the edge of the paved road are two obnoxious non-native grasses: Crab grass and Dallis grass. We looked at crab grass, with its oval leaves and delicate branched seed head, each branch bearing spikelets with multiple florets. The dark purple anthers of the dallis grass are still visible, indicating that it is still actively reproducing. At the edge of the ROW is a mat of distinctly greener Bermuda grass all around the base of the a bird box. Bermuda grass has a narrower leaf than crab grass but has a similar branched seed head. Being the turf grass of choice for decades, there are probably hundreds of cultivars of bermuda grass. The goal here at the Garden is to eventually eradicate all of the bermuda grass in the ROW as part of the development of Prairie on the Hill Project. Bermuda grass will be replaced with various species of native grasses and colorful prairie wildflowers typical of our southeastern prairie ecosystems.
Further up the ROW, we stopped at a patch of the exotic invasive Fountain grass. Its spikelike seed head resembles that of the foxtail grasses but is larger and purplish. The seed heads or plumes consist of stacks of spikelets that radiate from the central stem. The fountain grass was covered in dew drops this morning and many had the tiny delicate bowl-and-doily spider webs.
Foxtail grass seed heads

Yellow foxtail grass 
In the vicinity of the fountain grass were several large clumps of the native Yellow foxtail grass and a few examples of Pennsylvania smartweed. Key to the identification of smartweeds is the sheath (ocrea) at the base of the leaf stalk that wraps around the stem.
Purple top (Greasy grass) grows here at the open at the edge of the ROW. The spikelets in their airy, pyramid-shaped cluster have lost their distinctly purple color and have now turned brown. However, its distinctive drooping delicate branches are still helpful for identification. We noted that the stem and seed heads has become infected with a black fungus.
Broomsedge floret emerging from the spath
Broomsedge is visible at the south edge of the Elaine Nash Prairie Project. One thing that sets it apart from other bluestem grasses is the small leafy structure called a spathe which initially encloses the spikelet. Eventually the entire spikelet emerges from the spathe, covering the seed head with white puffs (the genus name, Andropogon, means “man beard” in Latin, referring to the hairy spikelets that most species in this genus have). Broomsedge looks a lot like Splitbeard bluestem but if you can find the spathe you know you have broomsedge. Both have the alternating “blue” and red sections of stems.
River oats
River oats, also called “fish on a pole” by some, is here. Each dangling “fish” on river oats is a spikelet consisting of multiple florets. At the base of each spikelet are two glumes. Dale says learning about grass structures make him gloomy.
Vasey Grass, another large, exotic invasive grass, has a seed head that consists of several erect branches lined with four rows of round spikelets stacked like coins along the branch. Each spikelet contains only one floret. Linda noticed that it, too, was infected with a fungus, this one orange in color.
Thread-waisted wasp
Rosemary found a mildly torpid Thread-waisted wasp on a grass stem. The genus name, Ammophila, means sand lover. They are solitary wasps, meaning that they do not live in a colony like paper wasps. Each individual female wasp is solely responsible for building a nest and provisioning it for her offspring. As the genus name implies, they like sandy soil for digging their tunnel nests. She hunts caterpillars and when she finds one she stings it, paralyzing, but not killing it. She takes the paralyzed caterpillar back to her tunnel nest and lays an egg on it. She then closes the nest entrance and leaves her offspring to fend for itself. They have remarkably long legs which they use to excavate their nursery tunnels.
Purple love grass
Purple love grass grows at this location and has a low rosette of leaves topped with a large, airy seed head. Its stems are fuzzy, and the seed head has extremely slender, spreading branches bearing small, multi-flowered spikelets.
Splitbeard bluestem
Splitbeard bluestem has stems that appear to have alternating bluish-green and reddish sections. The grass leaf consists of two parts: the blade that sticks out from the stem and the sheath, at the base of the blade that wraps around the stem. If you gently pull on the blade the sheath will peel back from the stem. The sheath wraps so tightly around the stem it appears to be the stem. The actual Splitbeard stem is reddish and the sheath is bluish-green, making the stalk appear banded with alternating bands of red and blue-green. The Splitbeard name describes the appearence of the seed head – it is very hairy and forks into two spikelets.
Frostweed with prominent green wings on stem
Clasping aster flower

Clasping aster leaves "clasping" the stem

The Frostweed, a white-flowered wingstem, has gone to seed and on one of the plants the stems has turned purple or red yet the wings remain bright green making the wings easily visible.
Many small, purple asters grow on the banks and in the areas with taller grasses. These are Purple clasping asters, so named because the base of the leaves appear to be wrapped partially around the stem. The leaves are sandpapery to the touch; the ray flowers are a pale purple, lighter in color than Georgia Aster.
A few bunches of Velvet witch grass are found next to the path. It's called velvet witch grass because of the presence of soft, fuzzy hairs on the stems and sheaths but no one knows why the entire genus is called witch grass. Like all members of this genus, the spikelets are tiny, containing a single floret, and are held at the tips of delicate wiry branches.
Caterpillar feeding on Silver Plume grass seed heads

The tall Silver plume grass seed heads harbor several small, tan caterpillars within the plumes. Dale has failed to find any reference to this grass being a host plant for any butterfly or moth.
Rosemary pointed out lichens on an entwined mass of smilax vines and called Don over to take a look. This unusual occurrence was pointed out to the group since the smilax vines are relatively fast-growing compared to the presumed growth rate of most lichens.
Beaked panic grass florets
Further up the ROW Beaked panic grass grows at the base of the bank. As with all members of this genus, the spikelets are small and contain a single floret held at the tip of a delicate, wiry branch. This species is distinguished by the way each spikelet narrows to a pointed tip, earning it the name “beaked” panic grass.
Big top lovegrass & Ramblers
Big top lovegrass was seen beside the path further up the ROW. Its seed head is a longer and less colorful version of the purple love grass seed head seen at the bottom of the path.
Cloudless sulphur chrysalis
A Cloudless sulphur butterfly chrysalis was spotted on a stem of Splitbeard bluestem. It is a beautiful pink and green chrysalis and this one was even more beautiful as it was bejeweled with tiny dew drops. (It's also possible that the chrysalis is a Sleepy Orange – they are very similar to Cloudless sulphur chrysalids.) Nearby Don noticed a recently vacated similar butterfly chrysalis. It was very pale yellow..
Bushy bluestem
Linda showed us an example of Bushy bluestem, which is appropriately named. Its seed head is really loaded with the hairs typical of the bluestems but its stems are not red and blue-green banded like the other bluestems. It is normally considered a wetland species and it is a mystery why it is found high on the hill here. Maybe the constipated duck theory?


Common Name
Scientific Name
Ginkgo biloba
Purple love grass
Eragrostis spectabilis
Paspalum urvillei
Panicum virgatum
Paspalum dilatatum
Crab grass
Digitaria sp.
Bermuda grass
Cynodon dactylon
Fountain grass
Pennisetum sp.
Bowl and doily spider
Frontinella cummunis
Yellow foxtail grass
Setaria pumila
Pennsylvania smartweed
Persicaria pensylvanicum
Purpletop or greasy grass
Tridens flavus
Andropogon virginicus
Funnel weaver spider
Family Agelenidae
Thread-waisted wasp
Ammophila sp.
River oats
Chasmanthium latifolium
Splitbeard bluestem
Andropogon ternarius
Verbesina alternifolia
Clasping aster
Aster adnatus  
Velvet witchgrass
Dichanthelum scoparium
Silver plume grass
Saccharum alopecuroides
caterpillar - silver plume grass

Beaked panicgrass
Panicum anceps
Big top lovegrass
Eragrostis hirsuta
Cloudless sulphur
Phoebis sennae
Bushy bluestem
Andropogon glomeratus

No comments:

Post a Comment

Post a comment