Today's Ramble was lead 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 Dale Hoyt.
No.
Attendees: 22
Today's reading was supplied by Rosemary. She intends to ramble in England in the near future, so she read a short history of the British Ramblers Association, followed by Bill Bryson's account of the famous (in Great Britain) Kinder Scout civil disobedience in his book, The Road to Little Dribbling:
Kinder (it rhymes with "cinder") Scout isn't a peak, but a grassy plateau, visible in clear weather from Manchester and Sheffield, both about twenty miles away. That was the root of the problem, it seems. Workers in Manchester and Sheffield gazed dreamily upon Kinder Scout from their gritty neighborhoods and thought of it as their hill, the place where they could go for fresh air and spiritual refreshment at weekends, and for years they did. But in the 1920s, the Duke of Devonshire closed Kinder Scout to the public for the sake of his grouse shooting. This naturally bred resentment, and in April 1932 five hundred people, mostly factory workers, gathered at Bowden Bridge to undertake a protest walk across the duke's land.
Tipped
off about
the hike, the duke's gamekeepers were
waiting and ordered the hikers to turn back. The result was a brief and
rather endearingly ineffectual
scuffle. One gamekeeper was knocked unconscious, probably accidentally, but
there were no other
injuries and the
walkers swept past the gamekeepers and completed their march to the
summit. The authorities,
overreacting,
arrested the
group's leaders and charged them with criminal trespass. Five men were sent to
prison for up to five months - an outrageously disproportionate punishment. The
result was a wave of anger and resentment that went well beyond
Derbyshire. The Mass Trespass (as it is now invariably written)
became an iconic moment in the history of both class struggle and the British countryside. In other countries they fight over politics and
religion. In Britain, it is over who gets to walk on a windswept
moor. I think that's rather splendid.
Dale followed Rosemary's reading with a brief history of
the origins of our Nature Ramblers;
details can be read here.
Don took a minute to thank Rosemary for the fine job she did as Ramble
photographer in the five weeks he was away.
Today's
route: Due to the heavy rains last night (4.05 inches in the last 24 hours)
there were several trees and a powerline downed in the Garden, making the
natural areas a little hazardous. Because of these problems we repeated the
route from two weeks ago (August 4), staying in the formal gardens. The morning
sky was clear, so we hoped for butterflies and other flying insects.
At the first junction of the American South Garden we spotted two large orb
webs, one high up between two trees, the other about shoulder level. These spiders,
plus another seen later this morning, are Triangulate Orbweavers, named
for the triangular mark on the back of the abdomen. This spider is frequently
encountered in the garden and toward the end of summer they are large enough to
produce very conspicuous webs.
 |
| Triangulate orbweaver The triangular mark can also be yellow |
 | |
| Web of the Triangulate orbweaver |
One question that always arises when a web is seen stretching between to
two trees is how did it get there? Did the spider start spinning a strand of
silk up high and then walk down the tree to the ground and up the next ree, spinning
a length of silk as she went? That seems unlikely, and it is, but the truth is
even a little more surprising. The spider begins by moving to the end of a
branch that is open to the surroundings. She lifts her abdomen and releases a
strand of silk from her spinnerettes, letting the breeze pull it out of her body.
The end is sticky and when (or if) it contacts a nearby object, like another
tree branch, it will adhere to it. When that happens the spider attaches her
end of the silk to her branch and walks along the newly established silken
bridge line, spinning out another thread, and anchoring it to the other end.
She then walks back on the double line to the center, attaches another strand
of silk to one of the bridge strands and drops down the earth below, releasing
another strand of silk as she goes. When she reaches the bottom she pulls down
the descending strand, creating a triangle in the air. (The triangle is formed
from the original bridge and the two sides of the second strand that was pulled
downward.) The point where the single, vertical strand meets the apex of the
silken triangle will be the hub of her web. She now climbs back up to the
future hub and uses this scaffold to spin and attach additional radial
anchoring strands. When there are enough anchoring strands she moves back to
the hub and begins to spin the orb of sticky capture silk, moving from the hub
in an ever increasing spiral until she is finished. She then carefully walks
back to the hub, touching only the non-sticky anchor strands, and sits, waiting
for her prey to blunder into and become stuck in the web.
By the way, these webs must have been spun after last night's rains stopped.
An unprotected spider web can't withstand heavy rains like those that fell last
night.
As we walked past the flower beds the most obvious thing we noticed was
that there weren't any bumble bees. In fact, we only sighted one lonely honey
bee visiting the blue Salvias, quite a change from two weeks ago when there
were dozens of bumble bees all over the Salvia.
Some Ramblers saw hummingbirds visiting the hanging baskets on the walls
of the conservatory.
 | |
| Cypress vine; note the long, tubular corolla and lacy foliage |
Linda pointed out a Cypress Vine with brilliant red, tubular
flowers. This flower color and shape is typical of hummingbird pollinated
flowers. It is in the Morning Glory family and has leaves that are pinnately
divided into very fine segments, creating a fern-like impression.
We saw two lizards this morning, a Green anole and an immature skink
(more about the skink later). Because there were a lot of questions about anoles I'm repeating a section of my post from August 4.
 | |
| Common Green anole in its brown coloration |
 | |
| Common Green anole in its green coloration |
The Green
anole is sometimes called the Carolina anole or the American chameleon. All
these common names, especially the last one, have been applied to the small,
green or brown lizards (Anolis
carolinensis) we saw today. It is not a true chameleon; they are lizards found
principally in sub-Saharan Africa, Madagascar, southern India and Sri Lanka.
They are much more adept at changing their color than our little anole. Our
anole is limited to changing its color between green and brown and does not
change color to match its background. Mature males have an extensible throat
fan, called a dewlap, that is colored pink or red. It is usually displayed when
another anole is entering the owner's territory and is thought to function as
both a territorial and sexual signal. It's used to attract lady anoles and
frighten away male trespassers. The dewlap display is usually accompanied by a
series of jerky pushups, in which the front of the body is elevated and lowered
several times in rapid succession. If the encroaching lizard is a male it may
flee or engage in a fight that the territory owner usually wins, if they are
evenly matched.
The pronunciation of "anole" is often a source of disagreement. I have heard many variations: 1)
"uh-KNOLL," 2) "AN-ol,"
3) "uh-KNOLL-ee," and 4)"AN-ol-ee."
In fact, five years ago I asked an anole expert for the proper pronunciation.
You can read the replies, mixed in with the origins of the word, here and here. The short version is simply this: you can pronounce it however you
wish – there is no preferred pronunciation.
How
Green anoles change color
The skin of anoles contains four layers of pigment cells.
The lowest layer consists of cells that contain the dark pigment melanin.
(Melanin is the pigment that produces a tan in human skin.) These cells, called
melanocytes or melanophores, have numerous lengthy extensions that reach
through the pigment cell layers above them. The melanin granules in the
melanocyte can either be huddled together in the cell body below the top layers
of pigment cells or dispersed into the long branches above the other pigment
cells. In the first case the color of the anole is green; in the second, brown,
the melanin pigment granules effectively covering the underlying pigment cells.
The change in color is controlled by hormones, especially adrenalin and MSH (Melanocyte
Stimulating Hormone). When excited or stressed the anole produces
adrenalin and the melanocytes concentrate their melanin in the cell body, revealing
the underlying green color. MSH has the opposite effect, causing the melanin to
disperse into the cell branches, covering up the green color.
Why
do Green anoles change color?
The conditions that cause Green anoles to change from
green to brown and vice versa are complicated and not well understood. This post
provides a summary of some of the studies that suggest how different social and
ecological factors affect the color of Green anoles.
 |
| Immature skink; perhaps a Five-lined skink but it could also be a Broad-headed skink or a Southeastern five-lined skink |
We found a juvenile skink
basking on the brickwork in the Herb & Physic gardens. A skink is a type of
lizard that has smooth, overlapping scales that gives it a slick, shiny appearance.
We can tell that this one was a juvenile because it had a dark body with five
yellow lines and a bright blue tail. All the common skink species in the area look
like this when they are immature. There are three skink species found in this
area: 1) the Five-lined skink, 2)
the Southeastern Five-lined skink or
3) the Broadheaded skink. The young
of all three species look almost identical – they can only be told apart by
looking at certain details of their scalation. To do that you need to capture
the animal. As these skinks mature they gradually lose their yellow lines and the
blue color on the tail. When they are mature the Broad-headed skink is larger
than the others. The head of the sexually mature male is very broad and has a
rusty orange color on its head at the back of the jaw. They are also more
arboreal (tree-loving) than either of the other two skinks. The Five-lined and
Southeastern five-lined are so similar at all ages that you have to have the
animal in hand to identify them.
All skinks share an unusual characteristic: they can
spontaneously drop their tail. The do this when they are threatened by a predator. The tail vertebrae have a fracture plane and
special muscles that, when contracted, break the vertebra along that plane. The
tail falls off, twitching violently, which attracts attention away from its owner.
Muscles in the stub left on the lizard contract and reduce or prevent the loss of blood. The tail can regenerate but the new growth differs in appearance, so you can
tell when a skink has experienced previous attacks by would-be predators.
Butterflies were in short supply today, probably because of last night's
heavy rainfall. It may have caused heavy mortality or the butterflies were
still chilled from the low temperature following the thunderstorms. We did see
a Silvery Checkerspot, Eastern Tiger Swallowtail and Giant Swallowtail.
 | |
| Silvery Checkerspot upper surface; at the edge of the hind wings is a row of black dots, some of which have open centers -- a character that separates the Silvery Checkerspot from the Pearl Crescent. |
 |
| This Silvery Checkerspot shows the lower surface of the hing wing; notice the rows of whitish to silver marks characteristic of this species. (photo by Dale Hoyt) |
The Silvery Checkerspot is hard to distinguish from a smaller
butterfly called the Pearl Crescent. The under surface of the hind wings has a
series of spots that are buff to silver in the Checkerspot. It is also larger
in size, but that does not help if you're inexperienced or don't have the two
sitting side by side. If all you can see is the upper surface of the wings the
best character is the row of black dots on the margin of the hind wing upper
surface. That row is surrounded by an orange field and at least one of the dots
within the field will have an open center; i.e., it will be a tiny circle
instead of a solid dot.
 | |
| Giant Swallowtail nectaring on Mexican Sunflower |
Other organisms:
 | |
| Paw Paw fruits |
The Paw Paw fruits are still intact but haven't changed color since the last time we checked. They are usually eaten by critters unknown (probably possums or raccoons) just before they ripen.
 |
| Long-legged fly (Dipter: family Dolichopodidae) |
While looking for the Paw Paw fruits we noticed a tiny fly sitting on one of the leaves. This turned out to be a Long-legged fly (family Dolichopodidae, if you're interested). The larvae of the flies in this family feed on aphids, so, if you're not an aphid, you could consider them a "beneficial" insect.
 |
| Black-eyed susan vine (Thunbergia sp.) |
Everyone was taken by the Black-eyed susan vine with its black centered tubular yellow flowers. It is unrelated to the "real" Black-eyed susan, which is in the sunflower family. The namesake vine is in the plant family Acanthaceae and is native to Africa, Madagascar and Asia.
 |
| Trifoliate orange -- wicked thorns! |
Another Asian introduced species, Trifoliate orange, impressed everyone with its compound leaves consisting of three leaflets (hence the trifoliate name) and wicked, wicked thorns. The plant is cold hardy so the root stock has been used in grafting other citrus family plants that are more sensitive to low temperatures. While we were looking at this plant as passerby told us that in Africa people use it has a hedge to keep hippopotamus out of their gardens. I've been unable to corroborate this information, but it is plausible. The fruit of the plant is extremely bitter.
We visited the Sorghum patch again, but the heavy rains washed all the honeydew off the leaves so the hundreds of bees and wasps we saw two weeks again were all absent. Lacking this focus for our attention someone pointed out that the next row over consisted of corn. which gave us a chance to compare these two similar plants.
The most obvious difference between the two is that Sorgum does not produce "ears" like corn where the leaves meet the stem. Corn ears are really inflorescences of female flowers, each flower giving rise to a single kernel of corn. Remember your botany? The female part of a flower is the pistil, which consists of an ovary, a style and a stigma. The ovary contains the egg cell(s), the stigma is the surface where pollen lands and germinates and the style is the part of the pistil that the pollen tube grows through to get to the egg. What do these part correspond to when you get an ear of corn to eat: the ovary develops into the fruit we call the kernel of corn, the silk is the style and the stigma is at the end of each silk. A pollen tube has to grow through the silk in order to fertilize the egg cell and initiate the development of the kernel. The silk can be 6 inches long, a tremendous distance for the microscopic pollen to have to grow.
Speaking of corn pollen, where does it com from? At the top of each corn plant a structure called the tassel develops. The tassel is an inflorescence of male flowers that produce the pollen. Corn is wind pollinated and the tassels have to produce a lot of pollen to guarantee that all the silks get at least one successful pollen tube.
The Sorghum plant has all its flowers at the top of the plant. It will produce seeds, but they will not be in ears. Unlike corn, Sorghum flowers have both male and female parts.
Growing on the benches by the Sorghum are a number of different lichens. A lichen is a symbiotic association between a fungus and a unicellular photosynthetic organism, either a blue-green bacteria or a green algal cells. The fungal part wraps around the photobionts and protects them and supplies them with water and mineral nutrients. The photobionts supply the fungus with sugars that they make by photosynthesis. The lichens grow on surfaces, but are not parasites. They simply use the surface as a place to grow. For over one hundred years it was known that lichens consisted of these two components but very recently it was discovered that some lichens incorporate a third entity, a kind of yeast. How widespread this is remains to be seen.
 | |
| Foliose, fruticose and crustose lichens |
Lichens exhibit several kinds of growth forms. The three commonest are called crustose, fruticose or foliose. Crustose lichens are like crusts, growing flat against a surface; foliose lichens have a leafy structure, i.e., parts that are elevated and not in contact with the surface they grow on. Fruticose lichens resemble bushy or shrubby plants. The lichens growing on the benches exhibit all three growth forms.
SUMMARY OF
OBSERVED SPECIES:
Triangulate
orbweaver spider Verrucosa
arenata
Ruby
throated hummingbird Archilochus
colubris
Salvia Salvia
sp.
Honey bee Apis mellifera.
Eastern
carpenter bee Xylocopa
virginica
Cypress
vine Ipomea
quamoclit
Hops Humulus
lupulus
Carolina
anole Anolis
carolinensis
Silvery checkerspot Chlosyne
nycteis
Black-eyed
Susan vine Thunbergia
alata
Common
evening primrose Oenothera
biennis
Tall
ironweed Vernonia
altissima
Paw paw Asimina
triloba
Tiny golden
fly Diptera: Dolichopodidae
Ginger lily Hedychium
coronarium
Spiked wild
indigo Baptisia
albescens
Confederate
rose Hibiscus
mutabilis
Spiked wild
indigo Baptisia
albescens
Skink Plestiodon sp.
Trifoliate
orange Poncinus
trifoliata
Castor bean
plant Ricinus
communis
Sorghum Sorghum
sp.
Corn Zea mays
Multicolored
Asian lady bettle Harmonia
axyridis
Various
lichen species ?
Sourwood Oxydendron
arboreum
Eastern
tiger swallowtail Papilio
glaucus
Giant
swallowtail Papilio cresphontes
Mexican
sunflower Tithonia
rotundifolia
Rose of
Sharon Hibiscus
syriacus
