Ramble Report May 18 2017

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.)

Today's post was written by Don Hunter, Linda Chafin and Dale Hoyt.

Twentyseven Ramblers met today.

Announcements:

Saturday, May 20, at 12:00 to 2:00 PM:

Annual Meeting of the Friends of the Georgia Museum of Natural History

GMNH Annex, 4435 Atlanta Highway, Athens 

Light snacks and adult beverages are free!

You and your friends can tour the Museum Annex, our equivalent of the Smithsonion's "attic."

All Ramblers are invited!

Directions: Take Atlanta Highway going west; turn left at Jimmie Daniels rd. (just past Sam's Club). Sam's Club will be on your left and the Museum Annex is the warehouse on the right. Turn right and park in the lot. Go around the building to the loading dock and enter.

Next week's Ramble will concentrate on medicinal plants. It will be lead by Melissa Ray, an Odum School graduate student.

No Reading today.

Today's Route:   We headed down to the lower end of the Dunson Native Flora Garden, via the road, then crossed back across the road to the powerline ROW above the road. We then headed up the ROW road to the top of the hill, then bushwhacked across the ROW over to the edge of the woods where we looked at a southern red oak. At this point we split into several groups and made our way back to the parking lot and Cafe Botanica.

American Beech fruit

American beech trees are bearing fruit (containing beech nuts). The golden-brown fruit husk has four segments and is covered with short, curved spines; the nuts contained within are three-sided. The perennial question arose:  was Beech-Nut chewing gum named for beeches? Wikipedia tells us that the company that made the gum started out as a ham- and bacon-producing enterprise in 1891, known as Beech-Nut Packing Company. Perhaps their hogs were fed beech nuts the way some hogs are fed on acorns? It was a common practice back in the day to turn hogs loose in the woods to find their own food, typically “mast” such as acorns and beech nuts.

Yucca flower

Yucca moth

At the lower end of the Dunson Garden is a group of Yucca plants just starting to bloom. Hiding inside the open blossoms are small, gray Yucca moths, about 1/2 inch in length. Shaking the stem of the inflorescence disturbs the moths and they fly out. These moths are in the flowers to lay eggs in the ovaries, where the yucca seeds develop. When the eggs hatch the caterpillars begin to feed on the developing yucca seeds. Of course to get seeds the flower must be pollinated and here things get a little surreal. The principal pollinator of the yucca flower is – the yucca moth!

The yucca stigma (the part of the pistil that receives pollen) is unusual. Instead of being exposed to the air it is tucked away in a recess at the end of the pistil. To be pollinated pollen must be inserted into the recess. This is the job of the yucca moth. When night falls the female moth gathers pollen from the anthers of her flower and rolls it into a ball. She then flies to another flower and, using unique, tentacle-like mouthpart found only in yucca moths, she tamps the pollen ball into the stigma recess. When she finishes she walks to the bottom of the pistil and lays a number of eggs in the wall of the ovary. In a peculiar sense she is farming yucca seeds. If she has done her job there will be more than enough developing seeds to feed all her caterpillars, with some left over to perpetuate the yucca.

But what if she lays too many eggs? Or another moth chooses to lay eggs in the same blossom? This is where the plant gets to "decide" what happens. It can somehow sense when the load of caterpillars is too great for its seeds to survive. Then the plant aborts the blossom. Researchers have examined aborted flowers and found multiple oviposition scars on their ovaries, showing that the moths often lay more eggs that a single blossom can support.

There is one more wrinkle in this system of checks and balances – cheating moths. There are several species of yucca moths that lack the special tentacle of the mutualist yucca moth. These moths can't and don't pollinate yucca flowers, they just lay their eggs in them, taking advantage of the efforts of other, pollinating, moth species. They are free-loaders, parasites on a mutualistic relationship.

When the caterpillars mature they eat their way out of the ovary and crawl into the leaf litter on the ground below the plant and construct a cocoon. Moths from some of these will emerge the following spring, but others cocoons can remain dormant for several years. One entomologist had a cocoon in a jar on his desk for over 10 years before a moth emerged.

This is a matter of critical timing. The moths have a short life span and the must emerge while the yuccas are flowering. If they emerge too early they may die before the yucca blooms; too late and they will not find any flowers to pollinate and oviposit in. How the plant and the insect are synchronized is currently unknown.

Leaf-footed Bugs on unopened Yucca blossom

 

Other insects are part of the fauna associated with the yucca plant. The most common of these is the Leaf-footed Bug. We saw several hanging out on unopened yucca blossoms. Bugs have piercing-sucking mouthparts and they, like the yucca moth caterpillars, feed on yucca seeds. Only they don't actually chew up the seeds, they pierce through the ovary wall with their beak and stab a developing seed. A digestive fluid is injected into the seed and the contents are sucked out. So the Leaf-footed Bug is also dependent on the yucca moth for its sustenance.

Linda pointed out the Purple Milkweed (rare and of special concern in Georgia) as we exited the Dunson garden heading over to the ROW.

Power line Right of Way (ROW):

Butterfly weed in bud

The Butterfly Weed Meadow is located on the left side of the ROW as you head uphill. It is been roped off to prevent mowing. Eight years ago there were seven Butterfly Weed plants in this area and by limiting mowing to late fall, there are now 70 or more. Today, we saw several that were in bud.

Hairy Cat's-Ear

Hairy Cat's-Ear (AKA Spotted Cat's-Ear) is currently blooming in many disturbed areas (which includes suburban yards). It resembles Dandelion at first glance, but has taller, solid green stems that branch and bear more than one flower. Dandelion stems are hollow and tan and always bear a single flower. Hairy cat's ear is a native of Eurasia and Linda says it has become a very aggressive, common weed in Georgia in the last 20 or so years.

Deptford Pink

Nearby we saw the beautiful, speckled, deep pink flowers of Deptford Pink, another European native, which is named for Deptford, a community southeast of London.

Field Madder

Growing with the Cat's Ear and just about everywhere else we saw lots of Field Madder. Another European native, field madder is found in disturbed areas throughout the eastern U.S. It’s hard to believe this tiny, weak-stemmed plant is in the same family (Rubiaceae) as the coffee plant!

Dove's foot cranes-bill

Dove's foot cranes-bill was also common–it’s another European native that is found in disturbed areas everywhere but does not really threaten any native plant communities.

Egg mass?

We stopped at what we first thought was a spittlebug foam mass but it turned out to be a cocoon or egg mass of some sort.

Wild Bergamot (Bee balm)

Prairie Restoration Plots. On previous Rambles we've pointed out several plots that experimented with different methods to remove Bermuda grass and Fescue. One of these plots has now been planted. Seen were Wild Bergamot and a geranium-like flower, Erodium cicutarium or Heron’s Bill AKA Redstem Filaree AKA Redstem Storks-Bill. A member of the Geranium family, Heron’s Bill is a European native. Linda speculated that its seeds might have lain dormant in the soil seed bank, subdued by the Bermuda grass that was growing here until it was removed last year. The tilling that was conducted as part of the project brought the seeds back to the surface where they germinated this year. Also seen was a Speedwell (Veronica sp.).

A few Bumblebees visited the Wild Bergamot but no honeybees were seen, even though several hives are only a few yards away. Unlike many insects, Bumblebees are able to elevate their body temperature many degrees above the ambient temperature, keeping their flight muscles warm enough to support activity on cloudy days like today. Honeybees can't do this.

A huge, dead Winter Creeper vine nearly engulfed a LobLolly Pine on the west side of the ROW. It was killed by Gary earlier in the year.

Queen Anne's Lace
Umbel lacking dark central flower

Queen Anne's Lace
Umbel with dark flower in center

Queen Anne's Lace
Close up of maroon flower in center

Queen Anne's Lace, with its large, flat-topped, compound umbels composed of many tiny white flowers, is blooming on the ROW. Tiny, black Tumbling Flower beetles are common on the flowers but very active; they flew off before the Ramblers got a look at them. The photo is one Don took last year. This individual lacked the dark purple floret in the center of the umbel, so it might be an American Queen Anne’s Lace (Daucus pusillus). But the European species, called Queen Anne's Lace, common in our area, doesn't always have the dark floret either.

Southern Beardtongue

Several Southern Beardtongue are blooming along the ROW road. If you look into the tubular flower, you’ll see several nectar guides (colored lines), four fertile stamens with anthers, and a fifth but sterile stamen, which lacks an anther but is covered with hairs. This is the “bearded tongue” which brushes pollen off the bodies of visiting insects (mostly bees).

Flowering Spurge

At one stop on the ROW road, we saw Flowering Spurge, Ebony Spleenwort, and Summer Bluet (AKA Purple Bluet or Large Bluet). The white “petals” on the flowering spurge are not petals at all but are glandular appendages that attract pollinators with their bright color and nectar. This species has separate female and male flowers on the same plant (i.e. the plant is monoecious); female flowers consist only of a single pistil–there are no petals or sepals; male flowers consist only of several stamens.

Eastern Needle Grass seed with twisted awn

Even though Eastern Needle Grass flowered last fall the old stalks still retain a few seeds with long awns. The awns twist and turn with variations in humidity and the seed is covered with sharp pointed barbs. When the seed lies on the surface of the soil the twisting action "screws" it into the soil and the barbs keep it from coming out. It's a system for automatically planting a seed. (The seeds also work their way through your socks and are hard to remove to eliminate the irritation.)

Another prominent grass remnant from last fall is the dried stalks of Silver Plume Grass. This grass is every bit as beautiful as the Pampas Grass and the silvery plume of seeds towers higher than the import from Argentina.

American Lady

American Lady caterpillar on Pussytoes

Even though it was cloudy we saw three butterflies, an American Lady basking in a sun fleck, a Cloudless Sulphur swiftly flying about the ROW and a third that flew off before we could get a good look at it. Susie thought it was a Swallowtail but Dale thought it might be a Silver spotted skipper, but neither was confident enough to argue about it. At the edge of the path a small group of Pussytoes was being consumed by an American lady caterpillar.

We saw several Small's ragwort, one of three ragworts we see around the Garden in the spring. All of them are native.

Carolina Horse Nettle

Carolina Horse Nettle is flowering and its tubular, yellow anthers are especially prominent. They are “buzz pollinated” by bees. The "nettle" in the common name suggests that it might sting like a nettle, but it merely has hidden, sharp spines that can cause pain from puncture and not poison, as in true nettles.

Dallis Grass is blooming and several Ramblers were treated to a hand lens view of the dark, fuzzy stigmas that project out into the air. Grasses are wind pollinated so their stigmas have a large surface area to capture pollen. These looked like miniature bottle brushes.

Thrips on deformed Wingstem leaf

Katherine found several wingstems with curled up leaves at the top of the young plant. We unfurled a few and found a thrips inside one of the leaves. Thrips are odd little insects. One of the two mandibles, the left, is enlarged and pointed. It is used to puncture plant cells, allowing the juices to be sucked out. Some are pest of plants, others feed on fungi and some are predators on mites, stabbing them with their left mandible. (Thrips is both singular and plural.)

Southern Red Oak leaves
(resembling Blackjack Oak)

We stopped at a Southern Red Oak on the western edge of the ROW and commented on how similar the shade leaves are to the leaves of blackjack oak. The lower leaves (shade leaves) look different from leaves higher up on the tree, which are called “sun leaves.” Lower leaves are wider and present more photosynthetic surface to the limited sunlight that penetrates to the lower limbs of the tree. Since the upper leaves have all the sunshine they need, they are narrower thereby reducing the amount of moisture that is lost during the process of photosynthesis and to drying winds.

Carolina Milkvine AKA Carolina Spinypod, a species of climbing milkvine with dark maroon flowers was twining over the grass. The combination of maroon flowers and a dead meat smell attracts pollinating flies.

Sensitive Briar

 

While working our way through the grass back to the ROW road, we saw Sensitive Briar, with its pink pompom flowers. The leaves of this low, trailing herb fold up when touched like those of the tree Mimosa.

Pencil Flower was seen along the White Trail between the ROW and the road. We also saw it frequently along the ROW road up the hill.

On the way back down the power line right of way a few Ramblers spotted a Brown-headed Cowbird. These birds have a nasty reputation among bird lovers because they are brood parasites, i.e., they lay their eggs in the nests of other bird species. The cowbird egg, along with the other eggs in the nest, are incubated and the young fed by the foster parents. In some cases the young cowbird is even larger than the bird that is feeding it. This behavior raises a number of questions: Why did brood parasitism arise in cowbirds? Why don't the foster parents evict the strange egg or chick? If the young cowbird is raised by a different species how does it learn to be a cowbird? The answers to these questions are partially known and briefly summarized below. You can read more details here, here and here.

Mafia cowbirds. One study found that female cowbirds continue to check the nests in which they have laid an egg. If they find the egg or their baby bird missing they will destroy the nest. The result is that the host that removes the cowbird egg from its nest raises fewer of its own young than hosts that allow the cowbird egg and chick remain in the nest. Apparently the protection racket is older than humanity.

Becoming a cowbird. Young birds have been shown to learn their species behavior by a process called imprinting. Within a very short period of time after hatching the baby bird becomes attached to the creature it first sees. This is usually the bird that incubated it as an egg or the bird that first feeds it. Later, it learns the calls or songs characteristic of the bird that is raising it. But a cowbird can't learn its species specific behavior that way – it would learn the wrong call. It would sound like a warbler or a robin or whichever bird had raised it. Ornithologists have recently discovered that young cowbirds often leave their nests at night, roosting near adult cowbirds. They also found that one cowbird call could function as a "secret password" that could unlock the fledglings ability to learn the appropriate songs. Until they hear the password, which is known as a "chatter" call, they are incapable of learning any vocalization. After hearing the first chatter call their brain changes and they become able to learn the calls of the adult cowbird.

How did brood parasitism arise? This answer is very conjectural. Before European colonization Cowbirds only occurred in the great plains of central North America. With the clearing of the forests beginning in the 1800s the cowbird spread eastward, followed by westward expansion as the west developed. It is suggested that the brood parasite habit arose because the birds originally followed the Bison herds, catching the insects that flew up as the large animals walked about eating grass. Since the Bison were migratory if the cowbirds followed them they would have to abandon their nests. By becoming brood parasites they could let other species raise their young and still follow the Bison. This has all the characteristics of a "Just so story," but that's all we have.

SUMMARY OF OBSERVED SPECIES:

American Beech	Fagus grandifolia
Curly-leaf Yucca	Yucca filamentosa
Yucca moth	Tegeticula yuccasella
Eastern Leaf-footed Bug	Leptoglossus phyllopus
Box Elder Bug	Boisea trivittata
Purple Milkweed	Asclepias purpurascens
Butterfly Weed	Asclepias tuberosa
Hairy Cat's-Ear	Hypochaeris radicata
Deptford Pink	Dianthus armeria
Field Madder	Sherardia arvensis
Dove's foot Cranes-bill	Geranium molle
Wild Bergamot	Monarda fistulosa
Redstem Storks-bill	Erodium cicutarium
Speedwell	Veronica sp.
Bumblebee	Bombus sp.
Winter Creeper	Euonymus fortunei
Queen Anne's Lace	Daucus pusillus
Southern Beardtongue	Penstemon australis
Flowering Spurge	Euphorbia corollata
Ebony Spleenwort	Asplenium platyneuron
Summer Bluet	Houstonia purpurea
Eastern Needle Grass	Piptochaetium avenaceum (Stipa avenacea)
Silver Plume Grass	Saccharum alopecuroides
American Lady	Vanessa virginiensis
Cloudless Sulphur	Phoebis sennae
Small's Ragwort	Packera anonyma
Carolina Horse-nettle	Solanum carolinense
Dallis grass	Paspalum sp.
Thrips	Order Thysanoptera
Southern Red Oak	Quercus falcata
Brown-headed Cowbird	Molothrus ater
Carolina Milkvine	Matelea carolinensis
Sensitive Briar	Mimosa microphylla
Pussytoes	Antennaria plantaginifolia
Pencil Flower	Stylosanthes biflora