JIM CONRAD'S
NATURALIST NEWSLETTER
Issued from the woods a few miles east of
NATCHEZ, MISSISSIPPI, USA

August 26, 2012

GRASS SPIDER
Deep in the bottom of the steep-walled, shadowy ravine below my trailer a funnel web -- a flat sheet of silk about half a meter across (20 inches), at its far side warping into a cylindrical tunnel about wide enough to put a finger into -- formed a more or less horizontal sheet beneath overhanging tree roots. It was a dark, somber place and leaves and dirt from above cluttered the web, giving it a forlorn and unattended look. However, a big, black, motionless spider stood guard near the tunnel. You can see all this in a flash-illuminated photograph, with the spider in the top, left corner, at http://www.backyardnature.net/n/12/120826sq.jpg.

A close-up of the spider, with two unusually long, silk-extruding spinnerets projecting from it rear end, and two distinct black, longitudinal lines crossing the white front body division, or cephalothorax, at http://www.backyardnature.net/n/12/120826sp.jpg.

The spider's body, not including the legs, was about 15mm long (9/16ths inch) so all spread out she was about 8cm long (3-¼ inches).

In my old Golden Nature Guide called A Guide to Spiders and Their Kin, the big spinnerets and the distinctive markings made it easy to figure out that this was a grass spider, genus Agelenopsis. However, our spider's rear body section, the abdomen, was much more rounded than those of Agelenopsis species illustrated in the book and on the Internet, plus no picture anywhere showed individual Agelenopsis spiders whose black cephalothorax lines were distinctly broken toward the back, like ours.

Happily, there's an active spider forum on the Internet where pictures of spiders are invited for identification, and several experts seem to be monitoring the forum full time. The forum is at http://www.spiders.us/forums/forumdisplay.php?f=5.

Within half an hour of my uploading our close-up, two folks had confirmed that it was indeed an Agelenopsis, and one suggested the species AGELENOPSIS NAEVIA, which I agree seems to be the most likely species. It was pointed out that abdomens on this species can be spherical like ours if it's a female full of eggs, or if it's just had a big meal.

However, pictures of Agelenopsis naevia don't show broken cephalothorax lines, so maybe we have a variation not represented on the Internet, or possibly even something new. By calling it Agelenopsis naevia here we make it easy for future experts working on the genus to find our picture and take it into consideration.

"Grass spider" is the general name for various species in the genus. Grass spiders are generally thought of as placing their funnel webs in grass or low bushes, so ours seems to have been a bit out of habitat. Grass Spider webs are not sticky like many webs, but the spiders themselves make up for this by being very fast runners. The moment something bumps into their web they race to the victim and pounce on it. Though grass spiders produce venom that paralyzes their prey, their fangs, or chelicerae, are too small to penetrate human skin, so grass spiders are harmless to people.

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PERSIMMONS TURNING YELLOW
When I was a kid back in Kentucky we used to tell one another to not bite into a persimmon until frost had sweetened them. Later in Mississippi I learned that in the fall persimmon fruits can be perfectly sweet without having experienced frost. Still, I've been thinking of persimmon fruits as late fall fare, so I was surprised this week to find fruits here already turning yellow, as you can see at http://www.backyardnature.net/n/12/120826ps.jpg.

After a mild winter, spring this year arrived three or four weeks early so maybe that explains the early yellowing. Of course the fruits still are way too hard and puckery to eat.

When a tree's branches are heavy with persimmon fruits it's easy to identify it as a Persimmon tree, which is DIOSPYROS VIRGINIANA. However, the Persimmon tree's simple leaves with no lobes or serrations on their margins are fairly similar to other trees such as Blackgum, Sourwood, Shingle Oak and more -- so fruitless trees can be hard to distinguish for beginners. One field mark distinguishing a Persimmon's leaf from a leaf of those other species is the longish, reddish, velvety petiole, and the leaf's rounded base.

You can't mistake a persimmon fruit for anything else, though. A close-up of one is at http://www.backyardnature.net/n/12/120826pt.jpg.

The spectacular feature of a persimmon fruit is its leathery, starfish-like "cap," which is what the flower's calyx has become. In most flowers the calyx is a green, inconspicuous part below a colorful corolla. However, once a Persimmon tree's flowers are pollinated the corolla shrivels away as it's supposed to, but the calyx -- at least on female flowers -- begins growing and toughening until it becomes what's shown in the picture.

Why do Persimmon trees expend such energy affixing large, tough calyxes to their fruits, when similar fruits such as apples and peaches do perfectly well without such appendages? In "Plant Physiology" magazine {August 2012, 159 (4)} Nakano et al say that Persimmon calyxes bear many stomata and serve as "gas exchange organs" responsible for sensing and regulating not only water stress, but other environmental factors as well. Moreover, developing calyxes contain chlorophyll and photosynthesize just as efficiently as leaves.

Between 400 and 500 persimmon species -- species in the genus Diospyros -- are recognized, with four species listed for North America. Most persimmon species are found throughout the world's tropics. Our North American species can be thought of as unusual Temperate-Zone manifestations of a mainly tropical genus. Persimmons are members of the Ebony Family, the Ebenaceae, which itself is predominantly tropical and subtropical. The most famous members of the genus Diospyros are the Ebony tree with its beautiful, black, dense wood, and the Japanese Persimmon, whose enormous fruits now are sold in many supermarkets. Mexico's Black Zapote, or Zapote Negro, is a persimmon, Diospyros digyna.

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RIPE MUSCADINE GRAPES
Also it seems very early for ripe Muscadines to be ready, but they are, sometimes many dark purple grapes littering the ground beneath vines climbed high into the canopy. Our Muscadine page introducing the species is at http://www.backyardnature.net/n/w/muscadin.htm.

You can see ripe Muscadine grapes picked from the forest floor this week at http://www.backyardnature.net/n/12/120826vk.jpg.

Notice how thick the grapes' skins are. It's tough skin, too, but the greenish pulp is juicy and sweet, and the grapes are tasty.

Also these days Muscadine vines often produce curtains of ground-seeking, branching roots issuing from airborne stems. You can see a vine crossing the sandy-bottomed, usually dry ravine below my trailer at http://www.backyardnature.net/n/12/120826vi.jpg.

Some roots in my hand are shown at http://www.backyardnature.net/n/12/120826vj.jpg.

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GRAPEFERN EMERGING
There's a primitive group of ferns with their spore producing part, instead of consisting of fruit-dots, or "sori," on the undersurfaces of their fronds like most ferns, group them in dense, grapelike clusters raised above the frond. It's the genus Botrychium, of which about 30 species are listed for North America. Most Botrychium species are called grapeferns because of their grapelike clusters of sporangia. The Botrychium species I usually run across, both in the US and Mexico, is the Rattlesnake Fern, Botrychium virginianum -- "rattlesnake" because those elevated clusters of sporangia are vaguely suggestive of a rattlesnake's tail stuck skyward. You can see this on our Rattlesnake Fern page is at http://www.backyardnature.net/n/x/rattle-f.htm.

Nowadays a less common, smaller species of Botrychium is emerging in this area, as shown in a flash-illuminated picture at http://www.backyardnature.net/n/12/120826bo.jpg.

Those grapeferns are growing on a nearly vertical slope in the very shady, moist bottom of a deep, wooded ravine below my trailer. They're Dissected Grapeferns, BOTRYCHIUM DISSECTUM. Besides their fronds being smaller than the Rattlesnake Fern's, the stems of their clusters of sporangia, or sporophores, attach to the blade stalk near the ground, not at the very base of the frond blade, high above the ground, as in the Rattlesnake Fern.

Dissected Grapeferns occur throughout the eastern US and adjacent Canada, plus here and there in the Caribbean. The online Flora of North America says that it habitat ranges from open grassy areas to deep forest. Here I find it only in moist places with rich soil, such as right beside my trailer door, in deep shade, where this fern is emerging right now. Flora of North America also says that Dissected Grapeferns emerge in late spring, but ours are definitely coming online in late summer.

*****

CHUNKS OF FERRICRETE
Sometimes embedded in the sand of the usually dry floor of our local deep ravines you find very heavy items such as what is shown at http://www.backyardnature.net/n/12/120826ir.jpg.

There you see particles of sand and gravel cemented together by a hard, dark substance into a rock. Here's that rock's story:

Here twelve miles east of Natchez and the Mississippi River our landscape is buried beneath a layer of maybe 20 to 40 feet of loess, which was deposited by wind at the end of the Ice Age about 15,000 years ago. The loess rests upon layers of unconsolidated, or loose, sand and gravel deposited by running Ice-Age water draining from the north some 700,000 years ago. Agate pebbles occur in the gravel, so we know that at least some of the gravel originated in the Lake Superior area, for that's the only source of agate upslope from us.

In geological terms, our buried sand and gravel's 700,000 year age is young. Its geological youth explains why it is unconsolidated: It simply hasn't had time for its particles to fuse into rock -- the sand to form sandstone and the pebbly gravel to form conglomerate. The same is true for nearly all the geology of the Deep South's lowland Coastal Plain Province. In short, in our area if you see a rock, nearly always it's been transported from someplace else with an older geology.

However, the heavy item in my hand in the above picture is an exception to the usual rock-forming process. It's a locally produced, very young rock. The usual rock-forming process, called lithification, consists of being buried deeply underground with tremendous weight squeezing from above over long periods of geologic time, or else melting in the proximity of molten magma or lava, and cooling into hard rock. Our rock could form so quickly because it lithified by a different process. It became a rock through chemistry. Basically, the sand and gravel particles "rusted together" just like a can of nails if left in standing water in a shed for a few years.

The item in my hand can be called ferricrete, which is defined as a hard, erosion-resistant layer of material at or near the land surface, consisting of sediments from non-local materials transported from elsewhere, cemented by iron oxide. The iron forms "rust" that fuses surrounding particles together. The word ferricrete is derived from the combination of ferruginous and concrete.

Sometimes here in southwestern Mississippi we find thin horizons of ferricrete with unconsolidated sand and/or gravel both above and below it. The ferricrete is hard, so it drastically slows the erosion process. Steep drop-offs can form at the ferricrete layer's edge. Sometimes loose sand and gravel wash from beneath the ferricrete layer so that the ferricrete layer projects a bit into open space. And sometimes chunks of overhanging ferricrete break off and wash downstream.

That's the history of the item in my hand in the photograph.

*****

MOVING FROM MISSISSIPPI TO TEXAS
Last Wednesday afternoon, in a ceremony we've conducted many times, Karen ferried me to the Natchez Bus Station. It's always sad to leave, but somehow I have to, and I did. Thank you Karen, thank you friend.

By sundown Thursday I was in Baton Rouge, Louisiana for a two-hour layover, then during the night off we went through the southern Louisiana bayou country and sometime early the next morning there was another layover of an hour and a half or so, in Houston, Texas. By sunup Friday morning I was in San Antonio, astonished that so far things had gone pretty well. Usually it's a battle in Houston to keep my baggage from going astray. Houston is always a mess. So I was standing there half dazed from the disjointed nigh, when a tremendous cracking thud sounded right behind me. I was wearing a small backpack with my laptop in it, to protect it. Somehow the backpack had come unzipped and the laptop had tumbled onto the hard tile floor. I was sure it was broken, but there wasn't time to check.

The early morning landscape west of San Antonio surprised me with its big, circular fields of irrigated cotton. Somehow I'd thought that using precious aquifer water for irrigating crops like cotton was a thing of the past, but there it was. There were also pastures with cattle in them, the grassland in this part of Texas greener than in the parched north, for lately this area has received some good rains. Here and there were patches of forest, but they were lower, more scrubby looking and more silver-green than the lush forests I'd just left in Mississippi. There were more dusty, sun-baked, sprawling and not-so-bustling little towns along the way. The farther west we traveled on the Kerrville Bus Company bus the scrubbier the forest looked, and the drier the little stream beds got. At the Uvalde County Line the woods got even lower and scrubbier.

I disembarked in the town of Uvalde, population about 16,000, more prosperous looking, faster paced and perky than the previous towns. "Oil fields in the area producing lots of oil these days," my host explained, who'd come to the station in his pickup truck to pick me up. At the local HEB superstore I got enough oatmeal, cornmeal, flour and the like to last several weeks, for I don't plan to come to town very often, and then we took off toward the north.

All the land I'd seen so far that morning had been pretty flat but after awhile hills starting forming in the haze toward the north. That was the edge of the Edwards Plateau. All the way from Mississippi I'd been on the flat Coastal Plain, but here the Coastal Plain ended exactly where the Cretaceous Limestone of the Edwards Plateau rose like some kind of ancient, highly eroded wall.

The Edwards Plateau's southern boundary is cut by many little streams that are dry most of the time and a few streams that are called rivers, which come and go. We followed one of those stream's little valleys north as low limestone hills crowded us on both sides. We crossed the stream -- the Dry Frio River -- several times. In Spanish Frío means cold, so this is the Dry, Cold River, though it was neither dry nor cold. Last year the drought here was so bad it did the Dry Frio did go dry, but that was unusual. This year the drought has moved north, and all summer the Dry Frio has remained a pretty little stream with certain spots where you'd just like to stop and lie and float awhile.

My host put me in what he calls "The Cabin." I plugged in my laptop and everything worked perfectly. This is a six-year-old Toshiba laptop that was with me when I lived in that dusty, corn-storing room of the Indian community in Chiapas. It's survived all that salty air along the Yucatan coast, and ants getting into it in the thatch-roof hut at Chichén Itzá, and a lot more you may remember if you've been with me awhile, and it's never given me a bit of trouble. Praised be Toshiba.

Anyway, here at The Cabin in the valley of the Dry Frio River there's a neighbor across a pasture with a black pony in it and I can hear her call her chickens, and her dogs when they bark in the night, and there are other neighbors here and there, but the critter-neighbor's place is the only one I can see, and it's far enough away that I think I could go naked and she'd not know it without binoculars.

My host and I -- a Newsletter reader who responded some months ago when I wrote that I was looking for someplace new -- have ideas for here that sound pretty good when we talk about them, but of course you never know how things will turn out. As of now I'm de-weeding five raised beds a good gardener before me left behind and I've sown a winter crop of mustard greens and cabbage, and maybe other things by the time you read this. A deer fence eight feet tall surrounds the beds so we have that taken care of. What I'm worried about is the leafcutter ants. I didn't know they got this far north. It's the leafcutters who'll do us in if we can't figure things out.

On my first evening here my host lead me to a certain Edwards Plateau, Cretaceous Limestone cliff overlooking the valley. You can see the view at http://www.backyardnature.net/n/12/120826tx.jpg.

My place is the larger, bluish item near the picture's center.

So, this is a fascinating area for a naturalist, a pretty one, and we have all kinds of interesting plans. This new adventure should be fun.

Stay tune, and thanks to you for coming along.

*****

FEATURED ESSAYS FROM THE PAST:

"Beach Jazzlet," from the June 19, 2011 Newsletter, at http://www.backyardnature.net/n/p/110619.htm.

"The Four Noble Truths," from the July 21, 2002 Newsletter, at http://www.backyardnature.net/n/p/020721.htm.

*****

Best wishes to all Newsletter readers,

Jim

All previous Newsletters are archived at http://www.backyardnature.net/n/.

Even without a Facebook account you may be able to access an index to this week's essays, with each essay on its own page and with images embedded in the text, on the Facebook page at http://www.facebook.com/pages/Jim-Conrads-Naturalist-Newsletter/412345652126940.

Visit Jim's backyard nature site at www.backyardnature.net