Sunday, July 17, 2016

What’s your pleasure? South Pass City or Miner’s Delight?

In 1868, a gold rush hit the southern Wind River Mountains. Hundreds of men infected by gold fever poured into the gulches, staking claims. They were followed by merchants, freighters, saloon keepers, brewers, and ladies of the night. Towns sprang up within weeks—tents, wooden shacks, hotels, stores, saloons, dance halls and jails. Soon the Carissa was processing ore, followed by the King Solomon, Hoosier Boy, Irish Jew, Mary Ellen and many others, on the order of 1500 mines and lodes in all. Regional population peaked at 1500-2000 in 1869. But just five years later, Wyoming’s largest gold rush (small by Western standards) was done. The dreamers went elsewhere. By 1880, the towns were all but abandoned.

Yet South Pass City still looks a lot like it did at the height of the boom. Wooden buildings line the dirt street. A saloon draws folks in for cold drinks on hot summer days. A woman slaves over a wood stove, baking cookies to sell. The dance hall does a brisk business (in entrance fees). But … something’s not right. The buildings are freshly-painted and well-kept; there are no burned remains anywhere. I walked the smooth clean dirt street, breathing fresh mountain air. I didn’t have to dodge ruts and horse manure, swat flies, or breathe dust. And it was quiet—no groaning wagons squealed and screeched down the steep grades into the gulch; no one yelled at the mules. No gun shots. The jail was empty.
At the Smith-Sherlock Company Store, I bought an ice cold pepsi, and learned that for the last fifty years, the State and volunteers have been resurrecting and maintaining South Pass City as a Historical Site. They restored or rebuilt the old buildings, complete with furnishings of the day (a booklet available at the dance hall provides details). On summer weekends and holidays, volunteers bring South Pass City to life, selling cold sas’sprilla at the saloon, and baking cookies. Just imagine a large dose of chaos and grime added in, and you can experience South Pass City as it was at its heyday.
There were five hotels in town at the peak of the rush, “with accommodations both rude and refined.”
Twenty saloons did business during the gold rush years. The Carissa was a late-comer, built in 1890 to slake the thirst of those attempting to revive the Carissa Mine and set off another boom (it fizzled).
This printing press started out in Cheyenne in early 1869, moved to Laramie in the spring, and by fall had settled in South Pass City. Nathan Baker published the South Pass News twice a week, at 15¢ a copy (source).
The Exchange (above and below) began as a bank, but became another of the town's saloons.
The Exchange was popular for its a card room.

In a gulch about eight miles northeast of South Pass City lies another boom town—Miner’s Delight. This one looks very different. There are no bright colors; in fact, little paint remains. Buildings sit slightly askew. Chinking has fallen from the log walls, and windows and doors are gone. Torn wall coverings decorate the rooms, now inhabited by mice and marmots. Through the ceilings, you can see the sky. 
To visit Miner’s Delight, park at the cemetery on the ridge. After enjoying the expansive views, walk through the gate and down the trail about a half mile into the gulch.
View from Miner's Delight cemetery. Oregon-California Trail is not far below.
Trail down to Spring Creek and Miner's Delight.
Cross the footbridge at the ponds on Spring Creek (beaver returned after the town was abandoned), and follow the old main street past buildings in various states of disrepair. Aspen trees encroach on some, and have taken over the collapsed stamp mill. This was where ore was crushed to be carried to South Pass City for assay, hopefully bringing the miner his delight.
Miner's Delight had its own stamp mill.
The town was named for a lode of gold—a miner’s delight—up on the ridge to the west. Ironically, it produced the greatest wealth in the South Pass Mining District, even though the town was the smallest and most isolated. Population peaked at around 100 in 1868, but the boom ended just two years later. A few “mini-booms” followed, repopulating the town briefly. It’s hard to believe this was once a scene of intense human activity, with homes, stores, saloons and a hotel. Now it's almost dead still. An occasional bird sings, and aspen leaves flutter in the breeze.
Miner’s Delight is managed by the Bureau of Land Management, which has stabilized the buildings to keep the town frozen in a state of abandonment and decay. The effect is powerful. I walked through the empty town, carefully stepped inside the structures, ran my hands over old wall paper, and picked up abandoned tools. I could imagine building, decorating and furnishing a new abode while dreaming of getting rich—or just making a decent living, which would have been fine enough for many of these people. And I couldn't help but wonder—how did they feel when they had to abandon their hard work and dreams just a few years later?
Poles hold up walls, inside and out.
This structure was moved here when Fort Stambaugh closed in 1878. Numbers marked logs for reassembly.

So, what’s your pleasure? Would you rather whoop it up on the main street of a booming gold rush town? … or listen to ghosts celebrate and lament the human condition in the peacefulness of aspen groves? I recommend both. Fortunately, South Pass City is not your typical tourist town. Visitation is generally light; there's not much to buy. If you need more excitement, head down into the gulch during Gold Rush Days.
Try your hand at gold-rush-style poker! (source).

For a more mystical experience, stroll through the towns after sunset. And listen carefully.
“Impossible, you say, impossible to believe several thousand people once lived here? People digging, pounding, shoveling, building, dreaming of gold, always gold. Others carousing, fighting and laughing. But go back again, late at night. Leave your car and walk away into a dark side street. And then listen to what you hear when the wind dies.” —Joyce Spita (1980)
Saloon keeper and State Senator "Cocktail Jimmy" Kime was the longest permanent resident of Miner's Delight. In fact, it appears he never left!


Humstone, M. 2004. Miner’s Delight interpretive plan. University of Wyoming. PDF

Lindmier, T., and Georgen, C. 2004. South Pass City; Wyoming’s city of gold. Virginia Beach, VA: Donning Company Publishers.

Spita, Joyce. 1980. A quick history of South Pass City, Atlantic City: Wyoming ghost towns. Colorado Springs, CO: Little London Press.

South Pass City State Historic Site walking guide. Available at the dance hall, with entrance fee. (PDF)

Monday, July 11, 2016

Should there be trees where once there were none—even though once (as now) there were many?

Cottonwoods, boxelders and willows along the Laramie River at Fort Laramie, on a hot day in 2016.

In southeast Wyoming, on the Laramie River just above the confluence with the North Platte, Fort Laramie still rises from the prairie. From its beginnings in the 1830s as a private fur-trading post, until the US military abandoned it in 1890, it was the most important outpost on the Northern Plains. Trappers, traders, Indians, emigrants, gold miners, soldiers and settlers all came here—for commerce, supplies, advice, news, negotiations, peace-making and war. For many, it was their only connection to the civilized but hostile world back East.
In 1849, the US Government bought the property from the American Fur Company to establish a US Army post, in part to make clear to Britain and Mexico that this was United States territory. The most important mission was protecting the tens of thousands of west-bound travelers who passed through each year on the Oregon/California Trail—probably the largest single land migration in history.

Most emigrants had “jumped off” at the Missouri River, and had been on the trail for over a month when they reached Fort Laramie. They averaged on the order of just 15 miles per day in the sweltering heat of the Great Plains, breathing dust churned up into great clouds by hooves, wagon wheels and human feet. The Fort was a welcome layover—a place to rest and fatten livestock, wash clothes, and repair wagons. It was one of the few places on the long journey to buy supplies.
Fort Laramie was about a third of the way from the Missouri River to the coast (source).
In the early 1850s, some 50,000 travelers were arriving at Fort Laramie each year! The total between 1841 and 1866 may have been 350,000, or as high as 500,000. These numbers speak to how difficult and dangerous life was for many people in the early days of our country. More than a few had lost everything to events beyond their control. What else could they do but leave, in hopes of something better? We were fortunate to have the huge sparsely-populated West and all it promised.
Immigration—ever the hopeful path to a better life. Painting by Alfred Jacob Miller (wikimedia).

My first visit to Fort Laramie was in July 1999, to prepare a vegetation map for the National Historic Site. It was hot! One afternoon while surveying open rolling country covered in sagebrush and grass, we came upon deep wagon ruts. They were overgrown but still obvious—remains of the Oregon Trail. Standing in the broiling sun, I looked down on the Laramie River several miles away, and was struck by how blessed and inviting its lush green gallery forests must have appeared to early travelers.

But I was wrong. There were no trees along the river at Fort Laramie during the great migration, no shade to soothe weary souls. They had been cut down years earlier, for buildings and fuel.

My misguided historical imaginings fell apart last week, when I returned to the Fort and saw this photo:
Crow delegation at the Fort Laramie council site in 1868 (from park interpretive sign).
Fort Laramie was an important council site. Indians set up camp on a large flat area east of the Laramie River, and prominent tribal leaders—Smoke, Red Cloud, Man Afraid of His Horses, Spotted Tail—met and negotiated with representatives of the US Government. Today, an interpretive sign near the river explains: “The ridgeline in this image [above] can still be seen if one looks east across the Laramie River.” But one has to look carefully to spot any landmarks, as the council site is now largely hidden from view by trees.
Should trees blocking the historical view be cut down? (arrows mark points on ridge visible in old photo)
In the absence of trees, what was used for fuel? I asked the friendly historian at the Visitor Center, who explained that the Army had a timber reservation on Laramie Peak 50 miles to the west; there was a lumber mill nearby. Soldiers were detailed to cut wood, and haul milled lumber and firewood back to the Fort. Though it was nice to get away—tedium and boredom being the biggest problems at Fort Laramie—it was dangerous. Lieutenant Levi P. Robinson met his end on a wood-cutting detail, killed by Indians. (Though there were skirmishes nearby, the fort itself was never attacked, being large and well-defended.)

When the Army closed Fort Laramie in 1890, trees were returning to the river. A century later, with cottonwood groves well established, a debate arose: if there were no trees during the historical period of interest, do today’s interfere with re-creation of those times?
Fort Laramie in 1875, viewed from across the tree-less Laramie River (source).
Fort Laramie in 1889, a year before it was abandoned. Trees line part of the river (source).
Fort Laramie in 2009, with cottonwoods, boxelders and willows along the river (Google Earth).
In 1980, historian Merrill J. Mattes argued in defense of historical accuracy:
“… need to have proper understanding and respect for the Fort's historic setting as well as its buildings. Over the decades the persistent efforts to plant parade ground trees which never existed during the "period of maximum importance," and to defend the post-1890 cottonwood grove along the river from any historical vista clearing … suggest that Park Service planners and managers have never been overly concerned with the sanctity of the historical setting.” (Mattes 1980; italics added).
I have to admit, the "cottonwood grove along the river” definitely confused my interpretation of the historical setting! It was more harsh than I had imagined. Perhaps some trees could be cleared to restore the historical view of the council site, but I think it would be fine to leave the rest. Last week, with temperatures in the 90s, I happily took a break in the shade of cottonwood trees along the river. It didn’t diminish at all my appreciation for how tough those early travelers were!

During our mapping project in 1999, we often took our lunch break in the saloon, cooled by an electric fan. “I’ll have a cold sas’sprilla” I’d say, pounding my fist on the bar in true Western style. Did soldiers and emigrants at Fort Laramie really have the option of an ice cold drink in the sweltering heat of midday? Most likely not, but I was sure glad we did!
On my return visit last week, I again headed over to the saloon, pounded my fist on the bar, and said, “I’ll have a cold sas’sprilla.” The bartender obliged. It was just as refreshing as I remembered.

Fort Laramie National Historic Site is open year-round, no charge. Dogs are allowed on leash (outside). Summer days are hot, but maybe that’s the best time to visit if you want the real emigrant experience (peak visitation back then was late May to early July).

• • •

This is my contribution to the July gathering of tree-followers, kindly hosted by The Squirrelbasket. In lieu of following a specific tree (too much work and travel), I’m posting about trees, at least for a few more months.


Buck, R. 2015. The Oregon Trail. Highly recommended (The New York Times agrees).

Mattes, MJ. 1980. Fort Laramie park history 1834-1977. National Park Service. Last updated 2003; available here.

National Park Service. 2014. Fort Laramie brochure. Available at the park.

Old photos, drawings and other images of Fort Laramie are available here (no charge for non-commercial use). Unfortunately there’s little information about the scenes and sources.

Wednesday, July 6, 2016

Yermo--a flamboyant and mysterious rare plant

Wyoming high desert with red indian paintbrush, blue larkspur, and lots of yellow flowers (in foreground; click on image to view). But where's yermo?

I walked slowly, zig-zagging uphill, scanning the ground, checking everything yellow—yellow flax, yellow wild buckwheat, various DYCs (damn yellow composites). But no yermo. Had I missed it? Was my attention flagging in the heat and wind? “Go slow, look carefully” I said, and wandered back downslope but further north. Still nothing. Uphill again. Near the top I stopped ... and burst out laughing. There it was—spectacular! Yermo can't be overlooked.
Yermo’s astonishing flamboyance.
Few Wyoming rare plants are as showy as yermo. It really stands out in the high desert setting, where aridity and wind favor low profile plants. Yermo is tall by local standards—up to a foot in height. The leaves are large, soft and fairly green, while most of its neighbors have dull tough drab little leaves, often covered in hair to keep precious moisture from evaporating.
Yermo in the ‘hood.
Yermo isn’t totally without desert adaptations. Up close, one sees the leaves are leathery and look a bit waxy. It has a substantial taproot that surely helps during hard times.
Yermo xanthocephalus, from the original description of the species (Dorn 1991).
In 1991, Bob Dorn, who knows the Wyoming flora well (he wrote Vascular Plants of Wyoming), was searching for a rare Phlox when he “encountered a very unusual plant”—as he wrote in his description of the new species (Dorn 1991). In fact, Yermo xanthocephalus wasn’t just a new species; it was unusual enough to be a new genus!

Yermo translates to “wilderness” or “wasteland”—an uninhabited place; xanthocephalus means “yellow head.” Thus the official common name is desert yellowhead, but "yermo" is used just as often, if not more.

Yermo is a member of the sunflower or daisy family, the Asteraceae. Like all members, it has composite heads of flowers. In this case there are just 4-6 flowers per head.
Five heads with just a few flowers each (the two lower heads haven't opened yet).
The distinctive keeled yellow bracts that enclose each small head are more obvious in bud.
Rosettes of leaves are young plants. Hopefully they'll produce flowering stalks in some future year.
There aren’t many yermo plants in the world. All of them grow in a tiny area of high desert, on the order of 35 square miles, in central Wyoming. For almost 20 years, botanists thought yermo was restricted to a single site. “We have searched far and wide for additional plants,” wrote Scott and Scott in 2009, “especially at sites with similar geological, geomorphological, and climatological characteristics, with no avail.” But then …

In 2010, a new population was discovered, on an escarpment “that had been intensively surveyed for many miles” except for a gap of about a mile and a half (Heidel et al. 2011). Plants will do that—defy human analysis and prediction. They may be completely absent from what we’ve identified as potential habitat, and then when we’re about to give up, we find them where they "shouldn’t be!”
Yermo mid photo, growing where no one looked until 2010.
Prior to 2010, many botanists visited yermo, and carefully studied its habitat. It was described as level to gently-sloping sparsely-vegetated outwash at the base of eroded slopes. Plants were more dense in concave areas or depressions, possibly sites of snow accumulation. Compared with adjacent sagebrush areas, yermo soils were slightly finer, more alkaline, and less able to retain moisture.
Original yermo site, where it grows on sparsely-vegetated outwash (click on image to view). WYNDD photo.
Everyone assumed yermo was an extreme habitat specialist. If there were more populations, they would be on similar sites. But yermo fooled the botanists. In 2010, it was found about five miles from the original population, not on sparsely-vegetated outwash but rather on the upper slopes of an escarpment, with bluebunch wheatgrass and junegrass, diverse forbs, and low shrubs. When I visited this site, I estimated vegetative cover to be 25-50%—not sparse. In addition, soil analysis has shown that the two sites differ significantly for at least 9 of 17 parameters measured (Heidel et al. 2011). Obviously we need to be more openminded.

The original population contains on the order of 10,000 plants—with several areas of concentration, scattered plants in between, and outliers. The second population contains 400 plants, in seven small isolated patches. Do these represent dispersal events? Is yermo spreading and colonizing new habitat?

In addition to its unusual robustness and limited inconsistent distribution, yermo is odd in another way. Many of our rare plants are difficult to distinguish from their close relatives; the South Pass rockcress, which I wrote about recently, is a prime example. But not yermo. Not only is it easy to recognize, it looks like nothing else! We have few clues as to its close relatives; we can only speculate.

Discoverer Bob Dorn considers yermo most closely related to several eastern North American species. He suggested it’s a relic of warmer wetter times when this part of Wyoming was forested—about 20 million years ago. That's when the sediments and ash that make up the rocks where yermo grows were deposited. With climate change—drying and cooling—forests retreated eastward, replaced by grassland and then desert. But it’s unlikely that yermo has been around that long. For one thing, diverse environments have intervened over the last 20 million years, including periglacial permafrost during Pleistocene times. Generally, there’s no reason to associate the age of a species with the age of the rock where it grows.

Still, yermo may be a relic species, just more recent. Equally possible, given how little we know, it may be a truly “new” species—the product of recent catastrophic evolution. Plants can make evolutionary leaps, for example through hybridization or genome duplication (multiple times even!). The resulting new species may look quite different from the parents.

Maybe when genome sequencing and analysis become really cheap, we can compare the full genomes of yermo and candidate relatives and figure all this out. I sure hope so! I would love to know yermo’s story. Why is it only here? Is it rare because it’s a holdover from a different time and environment? Or is it rare because it evolved recently and hasn’t had time to spread? Who are its parents? What’s its future? Will it persist, disperse seeds, and colonize new sites for botanists to find?
In 2002, Yermo xanthocephalus was listed as a Threatened species by the US Fish and Wildlife Service due to rarity and potential threats. Discovery of the second population in 2010 did not significantly change its status.


Dorn, RD. 1991. Yermo xanthocephalus (Asteraceae: Senecioneae): A new genus and species from Wyoming. Madroño 38:198 – 201.

Heidel, B., Fertig, W., Blomquist, F., and Abbott, T. 2008. Wyoming's Threatened and Endangered Species: Yermo xanthocephalus (desert yellowhead). Wyoming Bureau of Land Management, Cheyenne, WY. In collaboration with Wyoming Natural Diversity Database.  PDF

Heidel, B., Handley, J., and Andersen, M. 2011. Distribution and habitat requirements of Yermo xanthocephalus (desert yellowhead), Fremont County, Wyoming. Report prepared for the USDI Bureau of Land Management - Wyoming State Office by the Wyoming Natural Diversity Database - University of Wyoming, Laramie, WY.  PDF

Scott, RW, and Scott, BJ. 2009. Yermo xanthocephalus Dorn, a research report. Prepared for Bureau of Land Management. Central Wyoming College Herbarium and Scott Environmental Resources, Inc. in cooperation with Wyoming Natural Diversity Database. Riverton, WY. PDF

Friday, July 1, 2016

Plants & Rocks: South Pass Rockcress, South Pass Granite

The lineup.

At the southern end of the Wind River Mountains near South Pass—where thousands of travelers on the old Oregon Trail crossed the Continental Divide “with no toilsome ascents”—granite mounds rise above rolling sagebrush grassland like irregular lumps of clay. This is a great place to hang out if you like to conjure up the far distant past, for they mark the southwest edge of North America 2.5 billion years ago.
Late Archean South Pass granite; botanist (center) and field assistant (lower right) for scale.
But that wasn’t why I was wandering around these outcrops … slowly walking, walking, walking ... staring at the ground. I was searching for plants that grow nowhere else in the world. One has to look hard to find them. They’re inconspicuous, small, drab, and have no flowers this time of year. Not that flowers would help—they’re also inconspicuous, small, and drab.
The South Pass rockcress (aka small rockcress), about 10 cm tall; drawing by Isobel Nichols (source).
Thirty years ago, the South Pass rockcress (Boechera pusilla) was one of the targets in my first rare plant survey project. It was known from a a single location, which was only vaguely specified: “in cracks and crevices of huge metamorphosed [actually igneous] rocks off Wyoming State Highway 28, 39 miles southwest of Lander,” collected in 1981.

Boechera is part of the mustard family (Brassicaceae). It’s a large genus of subtly-different species—109 in North America, and at least 25 in Wyoming (experts disagree on classification). The group is thought to be actively-evolving (source), which may explain why rockcresses are tough to identify, and why field botanists are happy to ignore them. But I couldn't.

The flowers are small, with little variation among species, so we depend on mature fruit—siliques—for identification. Those of the South Pass rockcress are relatively broad (to 2 mm) and arch downwards but not sharply so.
Boechera pusilla, with spreading-descending relatively-broad siliques (seed pods).
One also has to examine the hairs on the basal leaves, visible with a 10x hand lens (click on images below to enlarge). Are they sparse, and simple to few-branched (South Pass rockcress)? Or are they dense, and branched multiple times (other species in the area)?
Sparse simple-or-forked hairs on basal leaves of Boechera pusilla.
Dense fine dendritic hairs on basal leaves of Boechera pendulocarpa (dropseed rockcress).

These are tough decisions but unavoidable because at least four other rockcresses grow in the South Pass area. Some of them hybridize, making intermediates. It’s a mess.
[Boechera used to be part of Arabis] “The taxonomic complexity of Arabis, in the broad sense, is legendary … most of the problematic taxa come to reside in Boechera. A rare confluence of hybridization, apomixis, and polyploidy makes this one of the most difficult genera in the North American flora [emphasis added] (source).
Maybe you can imagine the agony of a young field botanist trying to find this rare rockcress among common ones. My strategy was to collect all the different rockcresses I saw, from multiple locations, and send them to the late Reed Rollins at Harvard University, the expert for the group. It was Rollins who collected the specimen from “huge metamorphosed rocks” in 1981. My collections came back from Harvard with only one labeled Boechera pusilla, the South Pass rockcress. Was it from the same location as Rollins’s 1981 specimen? We’ll never know, but in any case, this rockcress was obviously rare.

In fact, it's rare enough to be a Category 1 candidate for Federal listing under the Endangered Species Act. To avoid listing, the Bureau of Land Management has taken steps to protect it, including closing a four-wheel-drive road to the site, and funding regular monitoring.
We don't mind that we now have to walk to see the South Pass rockcress!
Yours truly, counting South Pass rockcress plants in 1988, the first year of monitoring. WYNDD.

I returned to the single known South Pass rockcress site this year, to help with monitoring. Now I have 30 years of experience searching for rare plants, many of which are difficult to distinguish from common relatives (why is that?—another of life’s unanswered questions). It was a lot easier to recognize our target. After examining the various rockcresses at the site, I was comfortable making identifications in the field. A cheat sheet helped:
Modified from Heidel 2005.

The first step in a rare plant survey involves visiting known sites to develop a search image for the target species—a pattern that will really grab your attention. In this case it was the small cluster of green leaves below one or several stems with dangling siliques (pods). If I spotted such a cluster, I then glanced at the width and position of the siliques (relatively broad, spreading or descending). Finally I got down at plant level with my hand lens, and looked for the distinctive hairs on the basal leaves.

Armed with this search image, I went hunting. At the single known site, the South Pass rockcress grows at the base of a large outcrop of South Pass granite, in low rocky habitat with pockets of gravely soil, pretty much at ground-level (see monitoring photo above). I drove around until I found similar sites, and then slowly criss-crossed potential habitat, eyes glued to the ground. At the third site, I was stopped dead in my tracks by a cluster of green leaves below dangling siliques. The hairs on the basal leaves confirmed it—this was a new location for the South Pass rockcress!
South Pass rockcress grows among low rocks mid photo; main outcrop visible behind on right.
Microhabitat is gravely soil in pockets and crevices.
At knife-tip: cluster of green basal leaves, and three stems with drooping siliques. Not a photogenic plant!
Now the hard question—how much more is out there? How rare is the South Pass rockcress? There are many similar outcrops in the South Pass area … yet I had come up with only one specimen in all my collecting in 1986 … yet I didn’t really know what I was looking for then … and is it really restricted to just South Pass granite??! Obviously more work is needed.

The new site is exciting, but also discouraging. The population is really small, and with widely-scattered individual plants. Three of us, botanists all, went back two days later and it took us 15 minutes to find a plant. In all, we found only 11 after a thorough search of about 0.25 ha (half an acre). If this little rockcress sometimes (or often?) grows in small sparse populations, survey will be tough indeed.
Potential habitat: South Pass granite above rolling sagebrush grassland.

Finally, for the taxonomy geeks among us:
L to R: Boechera pendulocarpa, B. microphylla, B. pusilla.
Might the South Pass rockcress be a recently-evolved hybrid, rare because it hasn’t had time to disperse far? We know it’s an allotriploid (two sets of chromosomes from one parent, one from the other). Could it be the offspring of occasional crossing between the littleleaf and dropseed rockcresses? They’re common at both known sites, and …
“The sexual diploid species are relatively distinct from one another, but they hybridize wherever they come into contact [italics added]. Through apomixis and polyploidy, the hybrids become stable, self-propagating lineages. … for any pair of sexual diploid species (e.g., AA and BB), this process can yield different intermediates, including AB apomicts and both possible apomictic triploids (AAB and ABB). … Under these circumstances, even the most distinctive sexual diploid progenitors can become lost in a seemingly continuous range of morphological variability” (source).


Al-Shehbaz, IA, and Windham, MD. Boechera in the Flora of North America. (accessed 27 June 2016).

Heidel, B. 2005. Status of Boechera pusilla (small rockcress) in Wyoming. Prepared for the Bureau of Land Management. Wyoming Natural Diversity Database, Laramie, WY.

Marriott, H.J. 1986. A report on the status of Arabis pusilla, a Candidate Threatened species. Prepared for the US Fish and Wildlife Service by the Wyoming Natural Diversity Database, Laramie, WY.  Available here upon request.