NATCHEZ NATURALIST
NEWSLETTER:
from the woods near Natchez, Mississippi, USA

April 13, 2003

CROSSVINE FLOWERS GALORE
I've never seen the Crossvines, BIGNONIA CAPREOLATA, as pretty as they are now. This is a common woody vine in our area, as well as from the Gulf Coast north to Maryland and Missouri. It always bears pretty flowers, but this year the large blossoms are so abundant that again and again I find myself just standing looking at them. You can see a Crossvine close-up at http://aggie-horticulture.tamu.edu/county/smith/media/0021.jpg

Because Crossvines grow into the treetops, usually their flowers are too high to gain much attention. If you notice the flowers at all, typically it's when you find the discarded corollas on the ground. If you chance upon a discarded corolla -- unmistakable as a finger-thick blossom about 1.75 inch long (5 cm), with a yellowish-red exterior and orangish-yellow interior -- break open the corolla and notice how the stamens are attached. Stamens comprise a flower's male parts, each stamen consisting of a stemlike filament and a pollen-producing anther.

You'll find 4 conspicuous stamens attached to the corolla's inner face. These stamens arch to the top of the corolla so that when a pollinator enters, pollen will be daubed onto the pollinator's back. Also look closely at the very rear of the corolla, where it narrows. There you should find a tiny, curled fingerlike item. It's a vestigial, sterile stamen. Normal stamens are about 3/4-inch long (2 cm) but the vestigial one is only about 1/8-inch long (5 mm).

Crossvines belong to the Bignonia Family, along with our common red-flowered Trumpet Creeper vine, and the Catalpa tree. This mostly tropical family evolved from ancestors bearing the usual 5 stamens, but now the family seems to be drifting toward producing species with fewer than 5. Trumpet Creepers have 4 stamens, Catalpas have either 2 or 4 functional stamens (usually you can see 1 or 3 other sterile and vestigial ones), and our Crossvines have 4 fertile and one vestigial stamens. These rudimentary stamens are like the human appendix which served humankind when our ancestors ate lots of roughage. Now both the human appendix and the Bignonia Family's fifth stamen are evolving out of existence.

Crossvines get their name from the fact that if you snip their stem, in cross-section the stem's pith is in the shape of a cross. However, it's a pity to cut the stem of such a fine plant just to see an X-shaped pith.

*****

EATING BITTER DOCK
For months I've been eating armloads of mustard greens, turnip greens, kale and spinach from the garden, and there's no end in sight. Each morning I mix several cupfuls of chopped greens with two eggs and garlic, and my cornbread batter is more chopped greens than meal and flour.

In the garden this week I was picking some kale and noticed a healthy bunch of Bitter Dock, RUMEX OBTUSIFOLIUS, growing nearby -- about a dozen large leaves growing vertically like rabbit ears -- so I picked them, too. The next morning I made my green eggs of them, and they were good, as I knew they'd be. Bitter Dock only grows bitter in late spring when the flower inflorescence shoots up. My omelet tasted as if it had been made with spinach spritzed with lemon juice.

Bitter Dock grows as a common weed in my garden. It's a native of Europe and is now naturalized in waste areas through most of the US and southern Canada. My grandparents used to relish dock, but my parent's generation ignored it, and my own generation seldom heard of it. I can't see dock without thinking of my Grandma Conrad, who very seldom left her farm during my whole childhood. One day I went visiting and she was gone. When I heard she was out picking dock along the highway, I learned that dock was something special.

Dock is just as good as spinach, mustard greens or kale, and it has its own fine flavor. It's a robust plant with a tremendous taproot like a big parsnip. I didn't dig up the taproot producing my omelet leaves, so in a few days there will be another crop.

*****

VEIN POCKET GALL
Galls are growths produced on plants, usually but not always by insects, and galls come in an amazing variety of sizes and shapes. This a good time to "go galling," to just walk around noticing galls.

This week several expanding leaves of a Water Oak sapling next to my trailer developed fuzzy growths along their midveins, so naturally I did some gall- Googling. I also scanned a galled leaf and you can see that at www.backyardnature.net/pix/gallvpok.jpg

The leaves on my little Water Oak were afflicted with Vein Pocket Galls, which were caused by the larval (maggot) stages of very small flies called midges. The gall's existence begins when the tree's unfolding leaves start flattening out. At that time, the midge lays its eggs, the eggs hatch and the tiny maggots move to the veins and begin feeding. This causes vein tissue to start growing tumorlike, and in a few days the maggots find themselves encased in gall tissue. Later in the spring the mature larvae will drop to the ground and remain there through summer and fall, and over the winter. Then next spring the adult midge will emerge, lay its eggs on another Water Oak leaf, and the cycle will repeat.

*****

ROLY POLY GALL
While looking for more Vein Pocket Galls, I found some Black Oak leaves onto which it appeared that yellow- green grapes had somehow been stuck. At first I thought they were common Oak Apple Galls, but then I realized that unlike those galls, these were hollow. Moreover, inside each hollow gall resided a tiny (1/16-inch, 1 mm), yellow-green structure that looked something like a completely unattached egg with a round hole in it! You can see my scanned image of the gall at www.backyardnature.net/pix/gallropo.htm

Google told me that this was a Roly Poly Gall. It's caused by gall wasps in the genus Andricus and is called roly-poly because the wasp grub develops in that loose-egg-like structure inside the hollow gall. If the gall is shaken, the grub in its structure rolls around. Though the gall is common around my trailer, the whole story of the gall's life cycle isn't well known. The roly-poly gall is probably an alternate generation for a twig gall not now recognized. How does the rolling grub structure inside the gall gets its nutrients? Experts guess that it absorbs nutrients directly from the gall's wall as it rolls around inside it!

How about that? Here's something right outside my trailer door that's common, but science hasn't figured out its story yet.

If you're curious, you can see what the tiny Andricus wasp causing this gall looks like at http://host04.ipowerweb.com/~natureno/archivo/Botany/Andricus%20coriarius2.jpg

*****

BLACK VULTURE AND CONVERGENT EVOLUTION
Monday afternoon as I sat working at the computer suddenly there was a solid bang atop the trailer. I assumed that a limb had fallen from the big Pecan tree above me. But then I heard claws scratching the aluminum top and all I could think of was the time a large iguana fell onto my tin roof in Belize.

My trailer is so small that I can stand in the open door and peep over the roof. I did that and there was a Black Vulture, CORAGYPS ATRATUS, with a wingspread of about 54 inches (1.4 m). Naturally he instantly exploded into a huff of whooshing wings, and vanished behind some trees. I suppose I was lucky to get by with whooshing wings, for vultures have been known to indulge in projectile vomiting when upset.

I have no idea what this bird was doing up there, though the thought crossed my mind that maybe I shouldn't have skipped my spring bath (Joke; actually I took it). Anyway, you can see approximately what I saw the instant before my guest spotted me at www.primatesofpanama.org/pictures/avulture10.jpg

In that picture, notice the bird's powerfully hooked beak, beautifully designed to tear into flesh, just like a hawk's. This introduces an interesting fact.

My old, tattered and moldy birding field guide, copyright 1966, places vultures along with hawks and falcons in a single order. In other words, the authors of that book in 1966 assumed that vultures, hawks and falcons were all very closely related, having shared a common ancestor not far back in evolutionary history. One problem with that idea was that vulture feet are famously weak, while the feet of other predator birds are typically powerfully built.

Recent results from genetic sequencing have shown that our New World vultures are most closely related to storks and ibises, not hawks and falcons. Come to think of it, if you make a Wood Ibis black, and shorten its beak and legs, you pretty much have a vulture...

Vultures in Europe and Asia continue to be placed with hawks and falcons, however. Apparently Old World vultures do indeed share a recent ancestor with hawks and falcons.

This is a beautiful example of convergent evolution. Millions of years ago there was an ecological niche open for birds to fill, that of eating carrion. Since the carrion-eating "job" is done most effectively by birds who look and behave in a certain way, eventually, as Old World hawky birds evolved to fill that niche and New World storky birds did the same thing, the two unrelated groups of birds came to look and behave very similarly.

It's the same phenomenon that causes many Australian marsupial species to look like similar mammals here, though they are not at all closely related. Also it accounts for South Africa's succulent Euphorbias being so like our American cactuses. There's a good story from the NY Times on convergent evolution at www.cmnh.org/dinoarch/1998Dec/msg00381.html

*****

THIS WEEK'S MIGRATING BIRDS
n this week when both the Papaws were flowering with their musky-smelling, dark-brown blossoms and the Red Buckeyes issued their large, pyramid-shaped inflorescences of red flowers -- which looked very nice indeed against the forest's fresh, deep-dark greenness -- on Friday, April 11, I spotted the following migratory birds:

This week's new arrivals include the Eastern Wood Pewee, the Yellowthroat and the Yellow-breasted Chat -- all very common species here during the warm months but absent during the cold ones. The Eastern Wood Pewee winters from southern Central America, south; the Yellowthroat winters along the Gulf Coast south to Colombia and Venezuela, and; the Yellow-breasted Chat winters from Mexico to Panama, but sparingly along the southern US coasts.

*****

ON THE BEAUTY OF CONVERGENT EVOLUTION
Back to the vultures' convergent evolution, which I find very satisfying to think about. Again and again in nature you find very unrelated species evolving to look like one another. The reason is always the same: There's an optimum appearance and behavior for a species exploiting any specific ecological niche, so whatever ancestry you have, if you as a species decide to occupy that niche, your appearance and behavior will gradually evolve to the "optimum appearance and behavior" for that niche.

For me, the pretty part of this process is the confirmation that abstract ideals exist in nature and that, existing, they manifest themselves in the "real world." These abstract ideals are like ghosts suspended in eternity, beckoning parts of the changing world around them to come closer, to assume the character of the ideal's essence -- to become a material manifestation of their spiritual ideal.

Thus the Ghost of Carrion-eating Birds for millions of years called toward the bird world, and out of the mists stepped Old-World members of the hawk order, and New-World members of the stork order. After millennia of walking toward the Ghost of Carrion-eating Birds, the Old-World hawk volunteers and our New-World stork volunteers now look almost the same. What they look like is the ideal of the Ghost of Carrion-eating Birds, the ideal we know as the vulture.

What ghost beckons us humans forward as we evolve? What is the abstract ideal toward which we humans are walking out of the mists? What will be our final appearance and behavior?

For me, the search to an answer to those questions almost defines what it means to be a spiritual (not a religious) person. One's spiritual quest must be to glimpse the thing toward which humankind walks, and to keep consciously approaching that Holy Ghost, metamorphosing appropriately during the process.

My own journey is at an infantile stage, and I see the Ghost only at a very great distance and through profoundly disorienting mists. Yet already I can tell you two or three things I'm sure this Ghost favors.

She favors vitality over inertness. She favors evolution over inaction. She favors diversity over monotony.

These insights at first glance seem pretty general and unsexy. However, at this time when the flow of history is getting stuck in mindless conservatism, when fundamentalists deny the existence of biological evolution, and homogenizing "globalization" is the catchphrase of the times, maybe these insights are enough.