Tuesday, September 17, 2019

“gentians don't mind the first frost …”

Late summer on upper Deep Creek; Medicine Bow Mountains, Wyoming.
The wet meadow along Deep Creek was mostly dry. I walked through tall grasses and sedges topped with brown seed heads, their leaves turning yellow, and low shrubby willows with lusterless-green upturned leaves. But my feet stayed dry. Tiny ponds and mud holes were the only surface moisture. This is typical for September in the higher mountains.
Short field assistant deals with tall sedges and grasses.
What caught me by surprise were all the rich blue patches of life scattered about—a beautiful contrast!
But I shouldn't have been surprised. Pleated Gentians (Gentiana affinis) are always late bloomers. Yet I was caught off guard. It’s not that they were unexpected; they just aren’t part of the seasonal picture until I’m reminded.
Pleated Gentian, Gentiana affinis. Both flowers and buds were common. 

Gentiana is a large cosmopolitan genus, with on the order of 400 species. Most are native to the Northern Hemisphere. Many grow in montane to alpine habitats, where mountaineers love them for their showy displays on harsh sites, and their proclivity for blooming even as summer winds down.
Arctic or Whitish Gentian, Gentiana algida, “common to alpine settings in the Rocky Mountains.”
The Pleated Gentian is widespread in western North America, in moist habitats ranging from montane to alpine. Other common names include Trapper’s Gentian and Marsh Gentian (and there are probably more).

It’s odd that this gentian is designated "Pleated".  True, it does have folds or pleats between the petal lobes. But then so do all true gentians—members of the genus Gentiana (for example the Alpine Gentian above). The botanical term for this flower form is “plicate” meaning folded, like the pleats of a curtain.
Larger blue lobes are petal tips; smaller ones in-between are pleats.
Ragged tips of pleats show nicely in photo of Gentiana affinis by Rolf Englestrand [cropped].
When I first tried to identify this gentian, the flowers led me astray. I assumed that the dull green covering of the buds, which “persists” when the flower opens, was sepals—the outermost whorl of flower parts, usually green. But no … that green tissue is part of the petals. The sepals are indeed green, but they’re tiny and hidden under leaf-like bracts.
Pleated Gentian flower bud; just the green petal tissue is visible (see flower parts below).

Gentians were a favorite of the great mountaineer, naturalist and conservationist, John Muir. He often mentioned them in descriptions of mountain meadows in the Sierra Nevada of California. Muir especially appreciated their habit of blooming so late in the season, providing much-welcomed color.
“The gentians don't mind the first frost though their petals seem so delicate; they close every night as if going to sleep, and awake fresh as ever in the morning sun-glory.” from My First Summer in the Sierra (Chapter 10)

Friday, September 13, 2019

Tree-following: Changes!!

The leaves on the trees around the Art building are still green, but looking a bit dry.
WE HAVE NEWS! The haws on the Russian Hawthorns (Crataegus ambigua) that I’m following have turned red, as you can see in the next photo. Note also the rabbit by the rabbitbrush (Ericameria) which is in its prime right now (the rabbitbrush that is).
Okay, they’re hard to see. The next photo should help (click to enlarge):
Just one cluster of haws on the East Hawthorn (labeled in previous photo).
There are more haws on the West Hawthorn, scattered about.
Rabbit (left) and Rabbitbrush (right).
Many insects were visiting the rabbitbrush flowers. This is just a small sampling, and the photos are fuzzy because everybody was really zipping around. It’s wonderful to see so much activity in Laramie this time of year (mild September so far).
Bee, center of photo.
Not a bee I believe (but I'm NO entomologist).
Above and below—same butterfly, two views.
The fairy(?) castle now leans terribly. Maybe water from the torrential thunderstorm last week undermined it. Or maybe the fairies had a crazy wild party!
After greeting the Woman at the Entrance, who has a bloodshot left eye for some reason (that fairy party?), I took a peek inside the Art building: not much in the way of exhibits, though Agri[culture] is back, with new photos.
My fave.

This is my September report for our monthly virtual tree-following gathering, kindly hosted by The Squirrelbasket. More news from followers here. To join in the fun, check this post for information and encouragement!

Sunday, September 8, 2019

Communicating Earth Science: Stromatolite Stroll

Stromatolites showing off their arched layers.
As I mentioned a few posts back, I’ve been writing geology/history articles for our local paper, the Laramie Boomerang. Finding topics is easy; there’s no shortage of interesting features nearby. And telling their stories to the general public is doable and rewarding—if done right. But that’s the challenge.

The most recent article (below) was especially difficult, for it was about stromatolites. Ours are some of the most spectacular in the world, yet few locals know what a stromatolite is—much less that we have famous ones nearby. Adding to the challenge, their story is long, two billion years in fact. Finally, the Boomerang guarantees publication of only one photo!! This is a serious obstacle in explaining Earth Science, where a picture is indeed worth a thousand words. So I’ve added a few more for this post, including the cartoon at the head.

Most importantly, a many many thanks to Professor Emeritus and stromatolite expert Don Boyd! Don reviewed and edited my draft under most adverse conditions. First, the deadline was bumped up by a month, giving us only ten days for review and revision. Then the day after receiving the draft, Don broke his hip. That was Tuesday. On Thursday, he had it replaced. Physical therapy started Monday. But he continued editing, and we made the Wednesday deadline with a half day to spare. Don has a reputation for “being tough” and he certainly lived up to it (I suppose I should mention that he’s 92). His determination to stay active, physically and mentally, has made him a terrific role model for me!


Our Spectacular Stromatolites (Say what??)
by Hollis Marriott, Contributing History Columnist
Laramie Boomerang, September 1, 2019—“Laramie’s Living History”

“Big Daddy”—a humongous stromatolite now visible in cross-section, having been planed and polished by glacial ice. Medicine Bow Mountains, Wyoming.
High in the Medicine Bow Mountains west of Laramie, near the base of the Snowy Range, lie spectacular finely-layered rounded rock structures reminiscent of cabbage. These are stromatolites—in fact, some of the most spectacular stromatolites on Earth. They’re two billion years old, are now more than 10,000 feet above where they formed (sea level), and in some cases are true monsters (15+ ft. across!). Actually, we’re doubly lucky. Not only do we have world-famous stromatolites, there’s also a free guidebook that will lead us to the finest examples.

This is why “stromatolite” should be part of our vocabulary. The word is easy to say: “stroe MAT toe light.” And its Greek roots are appropriate: “stroma” means layer, “lithos” means rock. Stromatolites consist of thin layers of sediment cemented with calcium carbonate (the mineral that comprises seashells)—and thereby turned to rock.

It was geologist Ernst Kalkowsky who coined the term in 1908, for some unusual rock structures he discovered in the Harz Mountains of Germany. “The new term ‘Stromatolite’ is proposed for limestones with unique organization and structures … a fine, more or less even layered fabric,” he wrote. Furthermore the thin layers were arched, forming domes and mounds (usually sediments are deposited in horizontal layers). Kalkowsky suggested that stromatolites were biological—made by primitive organisms.

OUR “ALGAL (?) DOMES”

In the summer of 1917, geologist Eliot Blackwelder, then at the University of Illinois, and a student assistant, spent six weeks in the Medicine Bow Mountains studying the ancient, Precambrian rocks of the high central part. A young local geologist, S.H. Knight, son of Wyoming state geologist, Wilber C. Knight, joined them for part of the season. Blackwelder noted that though the Knights had visited the range on multiple occasions, “no detailed work seems to have been attempted and the results of such examinations do not appear to have been published.” That would change, but only after fifty years had passed.

After more fieldwork in 1925, Blackwelder prepared what would become a classic paper on the Precambrian geology of the Medicine Bow Mountains, published in 1926. He devoted two pages to what he considered some of the most interesting features in the range:
“There are many concentric domes, or globes, crowded together and all resting on a common base. These domes range in size from an inch or more to as much as 10 feet in radius. Their gross anatomy is generally emphasized by alternations of [dark and light layers], of which the latter weather out in relief. A close study of these features strongly suggests that they have been built by colonial organisms, such as calcareous algae.”
"Large dome-shaped structures" from Blackwelder's 1926 report (also in photo at end of post).

Blackwelder sent photographs, including the one above, to esteemed paleontologist Charles Walcott of the Smithsonian Institution, who concluded that the odd structures were biological, probably of algal origin. But in the absence of hard evidence, Blackwelder called them “algal (?) domes” in his paper.

His caution was understandable. In Blackwelder’s day and for decades after, it was thought that stromatolites had disappeared long ago, after organisms evolved that ate the algal builders. Therefore any explanation would have to be speculative. Though common as fossils, no modern-day stromatolites were available to illustrate how the ancient ones formed.

WRONG!

In 1956, oil company employees stumbled upon an odd sight on the west coast of Australia. In the warm super-salty water of a shallow bay stood many finely layered rock domes about three feet tall—“living” stromatolites! More have been found since then, usually in extreme habitats such as hypersaline lakes, atoll lagoons, and hydrothermal vents (including Yellowstone). Now it’s possible to study how stromatolites form.
Stromatolites in Shark Bay, west coast of Australia (ours are much bigger!); source.

First though, let’s be clear: stromatolites themselves are not alive. They are structures built by resident organisms and the accumulation of sediment. Ancient ones, like those in the Medicine Bow Mountains, are fossilized stromatolites, with little or no organic material remaining.

The most abundant inhabitants of modern-day stromatolites are bacteria, specifically cyanobacteria. Like plants, they photosynthesize—convert sunshine to energy. Cyanobacteria are quite primitive, and were among the earliest forms of life on Earth. These were the builders of the Medicine Bow stromatolites.

Stromatolite construction begins when cyanobacteria form a thin sticky mat—a biofilm—on the floor of a shallow body of water. Sand and silt periodically wash in and settle on the floor, covering the biofilm. When the sediment gets too thick for sunlight to penetrate, the cyanobacteria move up to colonize a new surface.

This happens repeatedly, producing a stack of thin alternating layers: biological, sedimentary, biological, sedimentary, etc. Cyanobacteria occupy the upper surfaces, basking in sunshine. Meanwhile, the layers are cemented with calcium carbonate, either from the water or the bacteria (or maybe both, we’re still learning). Without this cement, stromatolites wouldn’t survive a hundred years, much less two billion.

WYOMING BY THE SEA

Two billion years ago, Wyoming was located on the coast of a much smaller North America. Our stromatolites stood in warm shallow saltwater; in the absence of predators, resident cyanobacteria flourished in the sunshine. But these good times were not to last.

About 1.75 billion years ago, the coast was subjected to continental collision—goodbye ocean!—accompanied by mountain-building, which tilted the horizontal stromatolite-bearing rock layers to near vertical. Then 60 million years ago, there was more deformation when the Medicine Bow Mountains were pushed up during creation of the Rocky Mountains. This was followed by tens of millions of years of erosion culminating in scraping, planing, and polishing by glacial ice until just recently (about 11,000 years ago).

Now these relics of a subtropical ocean lie far from any coast, over ten thousand feet above sea level, and covered in snow for half the year—a graphic example of the dramatic change possible with the immensity of geologic time.

Actually, given all that has happened, it’s quite remarkable that the stromatolites of the Medicine Bows have survived. That they remain largely intact and recognizable is a stroke of good fortune for us— we can stroll among ancient stromatolites, ponder the passage of two billion years, and imagine a very different world. But to find this world, we need a guide.

NOW YOU CAN SEE FOR YOURSELF

In the mid 1960s, fifty years after he worked with Eliot Blackwelder in the Medicine Bow Mountains, Samuel H. “Doc” Knight—by then a highly-respected geologist, beloved teacher, and professor emeritus at the University of Wyoming (UW)—finally found time to study the local stromatolites:
“The writer has visited many of the stromatolite occurrences with student groups during the past forty years. Only recently, upon his retirement, did the opportunity present itself to undertake a detailed study of the occurrence and character of these stromatolites.”

One of many detailed illustrations in Knight's 1968 paper. Added arrow points to stromatolite in Blackwelder's paper and last photo of this post.
Knight spent six months in the field, over the course of three seasons, assisted by his grandson David Keefer. They mapped, measured, described, drew, and photographed 150 stromatolite-bearing outcrops.  Knight’s pioneering paper, Precambrian stromatolites, bioherms and reefs in the lower half of the Nash Formation (1968), drew international attention. As a result, the UW Department of Geology and Geophysics and the UW Geological Museum fielded numerous inquiries: “Where are the stromatolites in the Medicine Bow Mountains? How do we get there?” After forty years of this, it was clear that an updated publication was needed.

Professors Donald W. Boyd of UW (who was introduced to the Medicine Bow stromatolites by Doc Knight, in 1956), and David R. Lageson of Montana State University devoted themselves to the task. They relocated, photographed, and took GPS waypoints for many of the stromatolites described by Knight, and developed a walking tour that includes some of the best examples. Their Self-guided walking tour of Paleoproterozoic stromatolites in the Medicine Bow Mountains—“an illustrated field guide to some of the world’s best stromatolite outcrops”—was published in 2014 by the Wyoming State Geological Survey. It’s available free online.

The guide includes information about stromatolites in general, as well as those of the Medicine Bows. This is followed by the walking tour, and directions to other sites. While much of the text is technical, the introductory material, map, photos, and GPS coordinates will be useful to anyone who wants to stroll among our stromatolites, and contemplate the immense changes in the Earth that they represent.

The most accessible stromatolites lie adjacent to the road into the Sugarloaf Recreation Area, just a half-mile from the Snowy Range Road (Wyoming 130). The cabbage-like structures are obvious (left photo, with Professor Boyd). It’s easiest to park at the Sugarloaf Picnic Area (pass required), and then stroll a quarter mile back to the site. For details, see “STOP #10” in the guidebook.
Guidebook author Don Boyd kneels by stromatolites along Sugarloaf Recreation Area Road. Having been tilted 90º, they’re now seen in cross-section, as “cabbages.” Arrow shows original orientation—youngest growth surface on the right.
Those who are more adventurous will want to do the walking tour, which includes the famous Big Daddy at Prospector Lake, and the wonderful Valley of Stromatolites (right photo). The tour traverses an old road, overgrown in places, and includes several cross-country options. Distance is roughly 1.5-2.0 miles, depending on options. Follow the guidebook’s detailed directions carefully, and refer to the excellent photos. For reassurance, bring a GPS-capable device. The tour starts off Forest Road 332 (dirt), which is rough and rocky in places. Snow can be late in melting. For conditions, check with the Forest Service office in Laramie.
Arrow points to famous 15-ft long compound stromatolite in the Valley of Stromatolites. Original orientation inferred from arching layers—“top” marks youngest growth surface. Blackwelder sent a photo of this "large dome-shaped structure" to Walcott at the Smithsonian, and included it in his 1926 paper.

Tuesday, September 3, 2019

Dwarf Lousewort & the Joy of Learning

On a cool bright May morning in the Egan Range of eastern Nevada, I was stopped in my tracks, stunned by what I saw. Glowing in the sunshine was a cluster of flowers that defied expectations. My brain struggled with conflicting input; there was even a moment of anguish. But as soon as I checked the plant guide, I experienced that combination of strange and familiar that brings surprise and then joy. Here growing with sagebrush and very little else, in an opening in dry pinyon-juniper woodland, were louseworts!—specifically Dwarf Louseworts, Pedicularis centranthera. (Broomrape Family, Orobanchaceae).

This was a surprise. I thought louseworts were plants of wet meadows, shady montane forests, and the subalpine zone. Furthermore, these plants had no long clusters of flowers standing well above the basal leaves. The flowering stems were so short that the flowers were nestled among the leaves. But they were typical lousewort flowers—petals united into a tube that was two-lipped at the opening, lower lip three-lobed, upper lip hood-like (called a galea, meaning shaped like a helmet).
Flowers of Dwarf Lousewort, Pedicularis centranthera., nestled in basal leaves.
Typical lousewort flower (Pedicularis bracteosa); photo source.
In addition to the Bracted Lousewort above, the following are those I'm most familiar with, all common in the mountains of southeast Wyoming:
Parrot’s Beak, P. racemosa, (Matt Lavin photo) grows in montane forests, woodlands and meadows.
Elephant Head Lousewort, P. groenlandica, is unmistakable! The galea has a “trunk” and the lateral lobes of the lower lip are enlarged to form “elephant ears” (photo source).
Elephant Heads in wet meadow, Medicine Bow Mountains, Wyoming.
But now, thanks to that joyful encounter with the Dwarf Lousewort, my concept of Pedicularis has been expanded to include pinyon-juniper habitat. In fact, this lousewort is common enough in pinyon-juniper woodland in the western United States that it’s often called Pinyon-Juniper Lousewort.
Sagebrush opening in pinyon-juniper woodland on Ward Mountain in the Egan Range.
Dwarf Lousewort prefers stony soils in pinyon-juniper woodland—tough plant! (Lesica & Fertig 2017)
But why “lousewort”? Because back when the genus was first described, by Carl Linneaus, it was thought that when cattle and sheep ate these plants, they became infested with lice. Wrong! But Linnaeus was the great namer, having invented 266 years ago the system of scientific names that we still use today, so we’re stuck with Pedicularis—from Pediculus, Latin for louse. As for the common name, though Pedicularis is sometimes called Wood Betony, Lousewort is far more common, at least in the western US (“wort” comes from the Old English “wyrt” meaning plant).

Sources

Fertig, Walter. No date. Plant of the Week: Leafy lousewort (Pedicularis racemosa). USDA Forest Service, Celebrating Wildflowers. https://www.fs.fed.us/wildflowers/plant-of-the-week/pedicularis_racemosa.shtml (accessed Sep 1, 2019).

Lesica, P and Fertig, W. 2017. Spring Wildflowers of Utah’s Red Rock Desert. Mountain Press. https://mountain-press.com/item_detail.php?item_key=767

Southwest Colorado Wildflowers. No date. Pedicularis centranthera. https://www.swcoloradowildflowers.com/Pink%20Enlarged%20Photo%20Pages/pedicularis%20centranthera.htm (accessed Sep 3, 2019).