The Phantom Plant

Sunk to the ankles in a mossy cushion, I looked up from marking a tally in my notebook.  Although the backdrop of cedar and spruce appeared typical in every respect, I was struck by just how extraordinary this particular swamp really was. Around me were the lavender blossoms of a plant only slightly more plentiful than Bigfoot: the mysterious western Jacob’s ladder.

My work as an ecologist for the Minnesota Biological Survey program of the DNR has taken me to some fantastic spots, but never have I felt as fortunate as when mingling with these legendary flowers. When first discovered in 1944, this patch of western Jacob’s ladder was considered a peculiar eastern outlier of a species that’s fairly common out West. But for decades afterward no one could find it again, and it faded into a phantom among our flora. Only the long hours of a former colleague, sleuthing through old documents and slogging through swamps, made it possible for me to relish the scene where I stood. The efforts of other scientists and naturalists turned up five more Midwestern populations of this oddity. And a different kind of work—genetic analysis—now suggests these lonely eastern outliers are in fact a species all their own, one of the rarest in the country.

Enchanted Swamplands

With lush carpets of moss, as saturated with color as with water, conifer swamps can feel enchanted. Yes, some are tangled with brush and pocked with pools of bottomless sludge. But where the brush thins out and the moss billows in waves, I half-expect to glimpse a fairy slipping into a hummock hole.

I have poked around conifer swamps for days upon days without ever spotting a fairy or a pot of gold. Frequently though, I revel in a treasury of spritely flowers. Orchids often abound—not in the acidic, almost sterile bogs of pure black spruce, but where the water carries more nutrients. These rich swamps are among my top targets when searching for new rare plant records.

After hours of scrambling over cedar logs and twisting through alder stems, it is a delight when my eyes fall upon a few delicate, yellow petals of Lapland buttercup. Or the purple-veined pouch of a ram’s head lady’s-slipper. I have even discovered new locations of bog adder’s mouth, a tiny, green orchid that barely peeks above the moss. But not the elusive western Jacob’s ladder. Only by monitoring known populations have I snagged the chance to behold those lavender blossoms.

The Sharp-Eyed Botanist

The story of the western Jacob’s ladder in Minnesota goes back to one of the state’s premier botanists. Around the time Olga Lakela began teaching college biology in Duluth in the 1930s, a Philadelphia botanist named Edgar Wherry was developing an identification key for the Jacob’s ladder genus, Polemonium. He mentioned to Lakela an unverified report of a Polemonium from a Midwestern swamp, and suggested she watch out for more of it. Several years later while she viewed a color film taken by a Hibbing wildflower enthusiast, Lakela must have jumped from her seat when the camera zoomed in to some spires of lavender in a cedar swamp.

Guided to the site the following July, in 1944, she collected some plants and sent pressed specimens to Wherry. He confirmed them as western Jacob’s ladder, Polemonium occidentale, known from the mountain West. Based on differences in leaf size and floral architecture, he described her collection as a new subspecies, calling it P. occidentale subsp. lacustre. The only other wild Polemonium in Minnesota is spreading Jacob’s ladder, a resident of the state’s southeastern forests.

With Lakela’s discovery, western Jacob’s ladder joined a handful of other western species with a separate, outlying population near the Great Lakes. Some, dwelling on cliffs or the rocky Superior shore, are among the rarest of Minnesota’s plants. Others, like thimbleberry, are quite common. Unlike other outliers, however, a tinge of doubt clung to western Jacob’s ladder like a burr to your bootlace.

In Search of a Phantom

Wherry assumed Lakela’s plants grew naturally, but some botanists questioned their origin, perhaps because they were found not far off a road. Even one of Lakela’s students noted that a specimen he collected could have come from human introduction. Years passed. Lakela retired and moved to Florida. People occasionally looked for her Jacob’s ladder, without success, and no one reported any new locations. When this happens to a plant or an animal, suspicion builds that it’s not out there at all. As memory fades, it becomes a phantom.

So, nearly 40 years later, when two budding botanists discovered some Jacob’s ladder in a Wisconsin cedar swamp, it is not surprising they struggled to explain such an apparition. They speculated the plants might have originated from seeds carried on the boots of foresters who had fought fires out West, casting doubt on Wherry’s determination of a separate subspecies. Despite the skepticism, a new population in a distant swamp actually rekindled interest, and the U.S. Fish and Wildlife Service decided to evaluate the subspecies for possible protection under the Endangered Species Act.

With new federal funding, DNR ecologist Nancy Sather launched a survey in 1988, combing through 38 conifer swamps, including the one Lakela described. The original collection came from somewhere in a vast expanse of soggy cedar bisected by a road. Bleary-eyed after wandering one side of it for two full days, Sather crossed the road one evening, thinking, “If I find this plant in here, it is only going to be because I stumbled over it.” And stumble over it she did just moments later. The phantom was found. Sather encountered no new Jacob’s ladder sites in her hunt, but a curious thing happened. Just as other ecologists geared up to expand the search even further, reports of two new locations came in, one just 15 miles from Lakela’s and one 50 miles to the south. Suddenly the number of known populations doubled.

For botanists Chel Anderson and Roger Lake these reports bolstered not just their optimism for finding more plants, but also their understanding of the habitat to target. Slogging through 10,000 acres of swampland over three years at 73 meticulously selected sites across northern Minnesota and Wisconsin, they fulfilled an epic quest for this species. For all that effort, they added just one new site to the tally: a small patch less than a mile away from the Wisconsin population. They also described the extent and density of all the populations, information that today serves as a baseline for comparison. Despite fresh awareness of its scarcity, the federal government dropped our western Jacob’s ladder from consideration for protection, citing uncertainty about its standing as a subspecies.

The last population turned up in 2001 as the Minnesota Biological Survey advanced into northern Minnesota with a statewide inventory of significant natural features, including rare plants. When Bruce Carlson first noticed the leaves, he figured it must be something else, but seeing the flowers, his reaction was “I’m not worthy!” Now supervisor of the program, he calls it “a lucky, once-in-a-lifetime discovery.”

Genetic Surprises

MBS ecologists went on to explore forests and wetlands throughout northern Minnesota, with high hopes of finding more western Jacob’s ladder. But to date, we have not added a single additional site. With countless conifer swamps around the Great Lakes, why does this phantom haunt so few? Part of the explanation is that not just any conifer swamp will do. The plant has always been found near glacial gravel deposits that have some component of calcium carbonate. Rainwater picks up minerals as it seeps through the gravel, and the plants grow where this “hard” groundwater is forced back to the surface, often forming wetter openings in the conifer canopy.

But groundwater upwelling does not fully explain the rarity either. Many swamps have upwelling and no Jacob’s ladder. One suggestion is that we are seeing the last remnants of a species in slow decline over thousands of years. As the last ice cap receded 10,000-20,000 years ago, the theory goes, western alpine plants expanded north into new habitat, and some of them spread eastward along the ice front. Later, as the climate warmed, they retreated into cooler, moister refuges around the Great Lakes. Perhaps Jacob’s ladder is still retreating.

In a 2018 doctoral dissertation for the University of Wisconsin, Jeff Rose investigated Polemonium history through genetics, revealing surprises hidden in the DNA of its leaves. Comparing our Jacob’s ladder to western plants, he demonstrated that genetically they diverged from each other about 2.6 million years ago, long before the last ice age. They may have arrived in the wake of the last glacier, but not as an expansion of Polemonium occidentale. The Great Lakes plants are as genetically distinct from western Jacob’s ladder as they are from other Polemonium species. Rose says they warrant recognition as their own species.

If that result holds up to scientific peer review, we will have to stop calling them western Jacob’s ladder. How does “Great Lakes Jacob’s ladder” sound? Even more consequentially, they will switch from being a rare subspecies of a common plant to one of the rarest plants in the country. In that light, recent MBS and Wisconsin DNR estimates of population sizes are distressing. Since the 1990s at least two of the six populations have shrunk precipitously, and a third wasn’t relocated in a brief search.

The cause of the decline is unclear. All the Jacob’s ladder swamps experienced logging to some degree in the past, and at one time plants were clearly more abundant and bloomed more profusely where the canopy had been opened. As trees have grown back and shaded these openings, the Jacob’s ladder in them has certainly thinned. Limited light does not appear to explain the overall decrease, however, because the most open site has suffered the most severe reduction, while the two largest populations are chugging along just fine at the two least disturbed sites. 

Easy to See, Hard to Find

Whatever the cause, David Remucal of the University of Minnesota Landscape Arboretum has made a backup. He has stored seeds in a frozen seed bank, along with those of other rare Minnesota plants, giving us a means of restoration if that becomes necessary. In the meantime he has refined methods of propagation and plans to establish seed production beds, where experiments can pry into the biological secrets of pollination and root spread.

Growing in a wetland at the arboretum are a few small bunches of Jacob’s ladder Remucal started from seed. Accessible by boardwalk, it is by far the easiest place in the world to see the laddered leaflets and lavender flowers of this phantom plant. Minnesotans should also watch for it whenever exploring an enchanted, if soggy, conifer swamp. Thousands of acres have been searched, but thousands more have not. The discovery of a lifetime may be waiting out there.