August 12, 2012
A TOAD'S CRANIAL CRESTS
Down in the deeply shaded, sublimely humid bottom of a wooded ravine below the trailer I was photographing slime mold on a disintegrating, moldering log when my elbow almost squashed a toad who all along had sat unmoving as I positioned myself here and there framing the slime. Apparently he was picking of fruit flies attracted to the slime. Slowly I pivoted the camera around, setting the shutter at a very slow 1/10th of a second because of the exceedingly dim light. You can see the toad, the background overexposed and colored strangely as a consequence of making the dark toad show up, at http://www.backyardnature.net/n/12/120812te.jpg.
I was tickled with this toad because toad identification can be tricky. To be sure which toad species is at hand I like to have mature ones. That's because atop an immature toad's head the cranial crests and parotoid glands are poorly developed, and the relative shapes and positions of those features are determinative in toad identification. Therefore, holding my breath I managed to very slowly position the camera right above the toad to get the picture at http://www.backyardnature.net/n/12/120812td.jpg.
The elongate bulges below the eyes are the parotoid glands, which are glands that secrete neurotoxins -- poisonous compounds that affect animal nervous systems. The toxin produced in toad parotoid glands works mainly on the heart in a way similar to that of digitalis. In Hawaii a child died after eating a toad killed by his father in a sugarcane field. Most dogs and cats leave toads alone but those who chomp down on certain species can be poisoned, even die.
In the picture the slender L-shaped ridges bracketing the bulging eyes and above the parotoid glands are the cranial crests. In my old Peterson reptile field guide line drawings show the exact configurations of the various toad species. You can see how I used them at http://www.backyardnature.net/n/12/120812tf.jpg.
I got a perfect match, and the verdict was: American Toad, BUFO AMERICANUS. The salient feature noted is that on our toad the horizontal segments of the cranial crests do not touch the top of the parotoid glands, but their tips, at least in once instance, do curl downward and join with the glands. I'd suspected that our shady toad was an American because a second, somewhat less precise feature of the American toad is that normally only one or two large warts arise from the toad's dark spots, while on the other common species it could have been, the Fowler's, normally there are three or more. You can see that our toad's dark spots contain just one or two warts.
American Toads are common throughout forested eastern North America, except that they're missing in much of the US Deep South -- absent along most of the Coastal Plain from North Carolina to Louisiana. We're maybe 50 miles north of the southernmost point of their distribution. American Toads are one of many plant and animal species occupying a fingerlike lobe of distribution area projecting surprisingly far south in our area, along the Mississippi River's eastern banks. That's thanks to the sheltered bottoms of our area's deep, protected ravines eroded into the 200-feet-or-so (60m) thick mantle of loess accumulated on the Mississippi River's eastern side.
So, finally, I'm sure we have American Toads here. But also I'm thinking that Fowler's Toads also may be present, and possibly Oak Toads as well. I just need to find more adults with well developed cranial crests and parotoid glands!
CRICKET IN THE DOGS' WATER
Before long night sounds will grow even more thunderous than they are now and among the lustiest night-singers will be the crickets. The other day when a cricket turned up floating in the dogs' water trough I felt sorry for the struggling cricket but glad to have a chance to take a good look at her. I knew she was a female because of the swordlike ovipositor projecting from her rear end. Ovipositors enable females to insert eggs below the ground, into cracks, etc. You can see our dog-water cricket rescued and drying out on my hairy arm at http://www.backyardnature.net/n/12/120812cr.jpg.
Calling something a cricket isn't being very precise. On the evolutionary Tree of Life if you look at a certain group of branches and twigs you see that there's a gradual transition between grasshoppers and crickets. Whole taxonomic families and subfamilies of crickets exist harboring numerous genera and dozens or hundreds of species. Among the various species-rich groups of kinds of crickets are camel crickets, sand crickets, mole crickets, bush crickets, tree crickets, ground crickets, field and house crickets...
Happily, on the Internet the University of Florida provides a nicely illustrated, easy to use online "Key to Families and Subfamilies of Crickets" at http://entnemdept.ufl.edu/walker/buzz/k340k1.htm.
There, mostly on the basis of the general shape and size, and the kind of spines on the tibia of our cricket's back leg I could confirm that our dog-water cricket was a member of the Field Cricket Subfamily, the Gryllinae. A page linked to from the key further helped me -- on the basis of comparing pictures -- that our cricket was a member of the genus Gryllus, the field cricket genus.
Currently a good guess is that in the US we have maybe over 30 recognized or soon-to-be-recognized field cricket species of the genus Gryllus, and for the most part they are all so morphologically similar that they are best distinguished by their songs and life histories.
So, I can't say which species of field cricket we have here. However, the most commonly listed one for our area and one supposed to be appearing about now is the Fall Field Cricket, GRYLLUS PENNSYLVANICUS, so that's what we'll call it here. Maybe a later field worker trying to figure out who we really have will be glad to see what a field cricket looks like that's been found in dog water in August in southwestern Mississippi.
By the way, notice that not only does our cricket bear the long, slender, swordlike ovipositor projecting backwards from the tip of her abdomen, but also there are two brown, antenna-like bristles on both sides of the ovipositor. Those are cerci (singular cercus). An online 2010 article by Mulder et al in the Journal of Neurophysiology finds that cricket cerci function as "a low-frequency, near-field extension of the animal's auditory system and encodes information about the direction and dynamic properties of low-velocity air currents with great accuracy and precision." In other words, cerci help crickets "hear" and locate very low sound frequencies and slight movements of air such as those an approaching predator might generate.
EARWIGS AMONG PEARS
Speaking of insects with oversized cerci on their rear ends, earwigs have very formidable looking ones, as shown at http://www.backyardnature.net/n/12/120812wg.jpg.
In the orchard most pears lying in grass beneath trees have earwigs sheltering and presumably feasting inside the pears' woodpecker-pecked holes. The half-inch long (14mm) earwig in the picture scampered from a hole onto the pear's skin as if to pose for our picture.
About 20 earwig species are listed for the US, with about ten documented in Texas. Learning that, because there's no wing venation to work with, I'd figured I'd never identify the earwig in our picture. However, on the Internet there's a well illustrated identification key to the common US species, which can be downloaded for free at http://www.cdc.gov/nceh/ehs/Docs/Pictorial_Keys/Earwigs.pdf.
That key cued me to notice that the earwig in our picture displays an easy to see and distinctive feature: Its legs and antennae bear dark splotches. That's a field mark for the most commonly encountered species in the US Deep South, the Ring-legged Earwig, EUBORELLIA ANNULIPES. That species is thought to be of European origin but has been spread to many parts of the world, both tropical and temperate.
Ring-legged Earwigs often occur in large numbers, omnivorously feeding on both plant and animal matter. Sometimes they cause modest damage nibbling succulent crops such as lettuce, leaving poop on the leaves. However, they also feed on such diverse prey as caterpillars, beetle larvae, and leafhoppers, so in the overall picture most experts think that the good earwigs do in a garden probably equals or outweighs the bad.
That's a male in our picture. A male's rear-end cerci are more curved and turn more sharply inward at the tip than a female's, which are much straighter. Males also possess ten abdominal segments whereas females possess eight.
Some earwig species bear flimsy, cellophane-like wings, which when not in use are folded under short forewings. Ring-legged Earwigs lack wings, however, so you just wonder how the species has been able to invade so many off-the-road locations.
Earwig cerci, or "pincers," are used to capture prey, defend themselves and to help fold their wings. A little species like the Ring-legged is perfectly harmless to humans, but some species are much larger and can inflict a bit of a pinch with their cerci.
SPARKLEBERRY/FARKLEBERRY FRUITS TURNING
Along the dry, scrubby crest of a loess ridge a small tree's crabapple-like fruits were turning purple, later to be black, as shown at http://www.backyardnature.net/n/12/120812vc.jpg.
That's a member of the genus Vaccinium, which means that it's actually a kind of blueberry. When the blueberries in the picture ripen they'll be edible but so bitter and tough that unless you're hungry you should just leave them for the birds, who love them.
You know that blueberries are produced on shrubs, often knee-high ones, but our ridgetop tree was about 12 feet tall (3.5m). That's OK, since this is VACCINIUM ARBOREUM, the "arboreum" pointing to its unusual arborescence, or "treeness." Books are about evenly divided as to whether the English name is Sparkleberry or Farkleberry. The literature seems to be silent as to why either name is appropriate.
Vaccinium arboreum is centered in the southeastern US but it's found as far north along the coast as Massachusetts and inland to Ontario and Kansas.
By the way, many of this tree's leaves were infected with the fungus forming the conspicuous orange-yellow splotches with black dots on two leaves in the picture. I'm guessing that that's caused by the fungus Ophiodothella vaccinii, which is known to infect Vaccinium arboreum. The black dots are the fungus's blister-like fruiting structures, technically called conidiomata. Inside them, the fungus's hyphae vegetatively (asexually) form reproductive spores that escape from an opening in each blister's center.
POISON IVY FRUITS TURNING WHITE
Poison Ivy, TOXICODENDRON RADICANS, snakes up the side of a big Black Oak tree next to my trailer. A side branch heavy with fruits is shown at http://www.backyardnature.net/n/12/120812to.jpg.
The easy way to distinguish Poison Ivy from other non-dermatitis-causing vines is that its leaves are trifoliate -- they're compound, consisting of three leaflets, easy to make out in the photo. The old saying is, "Leaflets of three, let it be... "
In that picture most of the fruits are green but a few are white. A close-up showing what's happening is at http://www.backyardnature.net/n/12/120812tt.jpg.
That picture shows that each fruit is covered with a pale, green, hairy "skin" and in some places that covering is separating from the white seed. Probably a bird has come nibbling at the skin. Otherwise the fruit would remain intact, the covering would turn white and wrinkled, and later birds will swallow the whole fruit, later to regurgitate the big seed in a new environment.
Here both Poison Ivy and Poison Oak are common. In general, Poison Ivy climbs high into trees while Poison Oak remains shrubby. However, we've seen in Oregon that Poison Oak sometimes becomes vinelike. Therefore I was sure to get that close-up of a fruit because Poison Oak's fruits lack the hairs and tiny bumps at the bases of hairs seen in the picture. Therefore we know we have Poison Ivy and not a viny Poison Oak.
There's taxonomic confusion about the different varieties of Poison Ivy, with variations of leaf hairiness helping define the varieties. Just for future fieldworkers wondering how hairy Poison Ivy leaves are in southwestern Mississippi I took the picture at http://www.backyardnature.net/n/12/120812ts.jpg.
Poison Ivy doesn't twine around stems like morning glories but rather its woody stems sprout adventitious roots that anchor the stem as it vertically ascends the host tree's bark, as shown at http://www.backyardnature.net/n/12/120812tr.jpg.
One neat feature about the Poison Ivy plant is that its buds are "naked" -- no protective scales cover them, as is the case with most buds on woody stems in our area. Instead, the future leaves and stems are invested heavily with rusty-colored hairs, as shown on the terminal bud at http://www.backyardnature.net/n/12/120812tq.jpg.
Naked buds are most commonly found on tropical plants, even though Poison Ivy occurs deep into Canada. However, Poison Ivy does belong to the Cashew Family, the Anacardiaceae, which is mostly tropical. That family embraces not only Cashew trees but also Mangos and Pistachios.
Poison Ivy's rashes are allergic reactions, and normally with allergies some people get them and others not. When I was a kid I would lie in Poison Ivy just to freak out my family, for I was completely resistant to its effects. Reaching my 50s, however, I began developing a little sensitivity to it. Juice from a broken stem daubed onto my skin would cause a mild rash but merely handling leaves and unbroken stems still is no problem for me. I'm surprised to read that in the old days one remedy for Poison Ivy rash was to rub Poison Ivy leaves on the rash, and even to eat the leaves. If I were sensitive to it, I don't think I'd experiment with that remedy.
In the fall it's impressive how many Poison Ivy fruits are available, and how many birds crave them, particularly woodpecker, warblers and vireos.
Poison Ivy thrives best at forest edges. Therefore, this is one species that has benefited from America's forests being reduced to many smaller plots.
ST. ANDREW'S CROSS'S YELLOW CROSSES
Nowadays a common, yellow-flowered, knee-high shrub catches the eye with its four quarter-inch long (8mm) petals asymmetrically arrayed like squashed Xs on reddish-brown, slender, stiff branches with opposite, simple leaves, as shown at http://www.backyardnature.net/n/12/120812hy.jpg.
A close-up shows the blossom's greenish, flattened ovary in the flower center bearing two diverging styles, and several stamens arising from the ovary's base, at http://www.backyardnature.net/n/12/120812hz.jpg.
The flower looks as if only two large sepals arise beneath its petals but actually there are four, just that one pair is much smaller.
These features depart quite a bit from the "average blossom" most of us carry in our heads, which is radially symmetrical, bears five sepals, five petals, maybe five stamens, and an egg-shaped ovary with one style in the center. Really this little flower is more iconoclastic than it seems at first glance.
Here we're talking about St. Andrew's Cross, HYPERICUM HYPERICOIDES, usually found in dry, open woods, on upland slopes and ridges and the like. It reaches as far north along the Atlantic coast as New York and Massachusetts, and inland to southern Illinois, and south through eastern Mexico, and through the Caribbean area.
St. Andrew's Cross is very closely related (same genus) to St. John Wort whose dried parts often are sold as an herbal remedy for depression. St. Andrew's Cross has been used traditionally for problems ranging from snakebites to diarrhea and kidney problems to skin problems, but nowadays it's not regarded as being particularly medicinal. One unusual feature is that contact with the sap can cause photosensitivity in certain people. Photosensitive people are more vulnerable to sunburn.
Deep in a forested, heavily shaded, rich-soiled ravine bottom I almost stepped on an orchid's slender, knee high flower cluster not only because it was so shadowy there but also because the inflorescence was so inconspicuous. You can see a flash-enhanced picture of it at http://www.backyardnature.net/n/12/120812cf.jpg.
A close-up of a single inch-long (2.5cm), pale, greenish-purple flower is shown at http://www.backyardnature.net/n/12/120812cg.jpg.
The most distinctive, easily seen feature of that blossom is its extremely long "spur" -- the slender, white item cutting horizontally across the picture. The idea behind such a long spur is that moths insert their long, strawlike proboscises into the spur to get at nectar at the spur's opposite tip, in the process pollinating the flower. A study on this species found that it is pollinated by noctuid moths, who usually are dull colored, night-flying species.
This is the Cranefly Orchid, TIPULARIA DISCOLOR, restricted to the Southeastern US except for Florida, and extending north to New York and southern Illinois. Its habitat is mainly humus-rich soil of deciduous woodlands exactly like what we have here on the lower slopes of our wooded ravines. Elsewhere Craneflies are often found in sandy, acid soils of oak-pine woods. They seem to have a special affinity for depressions under Sweetgum trees.
In our first picture you might have noticed that the flower cluster arose directly from the soil with no leaf in evidence anywhere. In late fall long after these flowers and their spindly stalks have faded the plant's underground corm will issue an evergreen leaf that is dark green above and dark purple below. Over the winter the leaf will photosynthesize and provide energy to the root. Then late the next spring the leaf will have disappeared and in mid-summer you'll get what you see here.
In orchids, pollen is produced in tiny packets called pollinaria. Flowers use special tricks to get the pollinaria stuck to their pollinators who then carry the pollinaria to the next flower and leave it on the female part. Cranefly Orchids are adapted so that when their noctuid moth calls, inserting its proboscis into the deep spur, pollinaria are attached to one of the moth's compound eyes.
ACORN PLUM GALLS FORMING
During earlier visits here we've seen that around October many spherical, purplish-red, white-speckled, grape-sized items are likely to be found beneath certain oak trees. You can see a handful of them and read about them -- they're called Acorn Plum Galls and they're formed by a kind of gall wasp -- at http://www.backyardnature.net/n/x/plumgall.htm.
Nowadays the galls are forming on immature acorn cups. You can see one arising from the base of a Black Oak's acorn cup at http://www.backyardnature.net/n/12/120812pg.jpg.
HAIRY FUNNEL MUSHROOM
Down in the steamy, shadowy bottom of a woody ravine below the trailer a tree trunk lay on a stream bank, black and spongy in a late stage of decomposition. A ten-ft section of it bristled with picturesque, hairy-topped, funnel-shaped mushrooms with caps about two inches across (5cm), as shown at http://www.backyardnature.net/n/12/120812fu.jpg.
At first I thought this was a new species for me, but then I noticed that toward the population's edges where the rotting drunk became drier and more exposed to the elements the mushrooms gradually morphed into a smaller, more compact form -- a form I've seen a lot of -- as shown at http://www.backyardnature.net/n/12/120812fx.jpg.
The extremely brown-hairy, leathery cap with a much sunken center is very unusual and distinctive. A close-up of the hairs is shown at http://www.backyardnature.net/n/12/120812fv.jpg.
Another distinctive feature of the species is how the spore-producing gills beneath the cap are so extremely thin and close-packed. They gradually melt into the stem with no clear contact zone, as shown with my thumb holding back the pliable cap, at http://www.backyardnature.net/n/12/120812fw.jpg.
This is LENTINUS CRINITIS, a species frequently documented on decaying logs along the US Gulf Coast, but so infrequently mentioned in mushroom guides that apparently it has no common English name. It needs an English name because in this area during dry spells when other mushrooms disappear, often it's our most conspicuous mushroom. Then it's dried into a tough, shriveled state, but it's a mushroom nonetheless. So, let's invent a name, calling it the Hairy Funnel, just so we can talk about it.
SLIME MOLD ATTACKS MUSHROOMS
This April we looked at a slime mold attacking another slime mold, as detailed at http://www.backyardnature.net/n/x/dogvomit.htm.
This week, part of the big population of Lentinus crinitis mushrooms described above similarly was being attacked by a slime mold, as rather dramatically shown at http://www.backyardnature.net/n/12/120812sk.jpg.
We saw above that Lentinus crinitus is basically white with a hairy, gray-black cap. In this picture the entire mushroom is covered and dripping with orange slime mold. In fact, a mushroom-populated area the size of a breadbox was orange with slime mold, as if someone had splashed a glass of orange paint there, as shown at http://www.backyardnature.net/n/12/120812sl.jpg.
We've seen that slime molds -- which are not fungi, plants or animals, but rather their own thing -- wander about like streaming trickles of gelatin, their moving, much branched bodies called plasmodia. In the last picture, plasmodia creep across the log's moist surface and up onto the mushrooms, feeding as they move. When conditions begin drying out the plasmodia will aggregate and form fruiting bodies of various shapes and colors, depending on the species, and that will be their reproductive stage. Not having the fruiting body, I can only guess that our species producing these plasmodia is a member of the genus PHYSARUM, because that's a common genus and at least some of its species produce orange plasmodia.
What a drama! Here the Lentinus mushrooms are prey to the more mobile slime mold plasmodia, who wander as predators. On the log nothing seems to be moving, yet what we see is an attack in progress, a fight to the death between two species in competition for scarce resources -- in this case nitrogen, phosphorus and other nutrients the mushrooms glean from the log, and which the slime mold is disposed to steal, by force.
FEATURED ESSAYS FROM THE PAST:
"Does Nature Teach Patience?" from the November 3, 2008 Newsletter, at http://www.backyardnature.net/n/p/081103.htm.
"Ritualization" from the January 24, 2010 Newsletter, at http://www.backyardnature.net/n/p/100124.htm.
Best wishes to all Newsletter readers,
All previous Newsletters are archived at www.backyardnature.net/n/.
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