The "Wild and Crazy" Foxglove Returns

 

 

Too many so-called ecological studies are superficial to the point of uselessness because they focus on one to three species, for one to three years, on one to three acres. The ecosystem doesn’t work that way.

Stuart Pimm

 

We reported on the eared false foxglove in 2012 following a mere two decades of study. One hundred years ago, you had to “ride the crazy train” to find this easy-come/easy-go annual plant, as we then explained. Our study of how to facilitate this plant's recovery continues, and year by year we learn. 

Here's a key element of our thinking: we're not doing this one species at a time. We facilitate certain needy and possibly important species within the flow of life among Somme's nearly 500 plant species as the formerly lost but now recovering, black soil savanna ecosystem changes radically – on the road to recovery, we hope. 

 

In 2012 we had quoted the Center for Plant Conservation on the plant then called Tomanthera auriculata and now called Agalinis auriculata:

 

This species globally has “About 40-50 known occurrences, most with populations of only 25-250 individuals. The largest populations were found in Arkansas, Mississippi, and Missouri. Recently discovered in Kentucky. Presumed extirpated in Michigan, New Jersey and Texas.”

 

Today there are more populations known, in part because people plant this false foxglove in prairie restorations. Is this hemi-parasite sustainable in its restored and original populations for the long term? 

The eared false foxglove is now found in 17 states, although it is imperiled in 15 of those 

and gone entirely from 4 others. At best, it is considered merely "vulnerable" in 2 states 

and secure in none. Map by NatureServe. 

 

We first noticed plants at Somme in 1998 after broadcasting seeds from an original nearby population some years earlier. Then, we have no records, probably meaning we found none, until 2003 when 31 plants appeared near where we'd first found them. We caged some after we noticed deer eating them. Then we noticed that voles were sneaking inside the deer-exclusion cages and cutting down the foxgloves to get their seeds. In 2004, eighteen plants bloomed, but only one survived the deer and voles. 

Dense areas of tall goldenrod and saw-tooth sunflower grew nearby. As we'd found these species sometimes inhibited more conservative vegetation, we began cutting them in hopes of expanding habitat for the foxglove, which seemed to work. We began a program of facilitating grown of the foxglove population by caging, scything, seed harvest, and seed broadcast to see if we could give this new species a better chance of finding niches at Somme.  

Our early monitoring is summarized in the graph below, showing modest numbers during this species’ 16-year long, iffy incubation period in the prairies and savannas of Somme Prairie Grove. Would it survive here? And then in 2011 – apparent success – at least for the short term:

 

Indeed, for three years after that report, numbers remained high. We stopped giving this species “intensive care” and didn't monitor it at all in 2016 and 2017. But when we counted in 2018, we found 54 plants. In 2019 we counted only 20.

 

Perhaps we should have felt fine about those low numbers, as they were in the range of what the Centers for Plant Conservation cited for the size of most populations. But as an “introduced” or “restored” population, it deserved a more skeptical look – especially for this kind of plant. As an annual, this false foxglove has to start over from seed every year, while growing in an ecosystem of highly-competitive perennials, densely packed. 

 

Another troubling sign – we noticed that most of the Somme plants predominantly grew in immature, temporary habitats – the very opposite of what we are working towards at Somme. Yes, perhaps this wild and crazy species has always depended on “disturbances” – but to survive here it would need to find niches in the kinds of disturbances that occur within relatively stable communities. Given where we had been finding most foxgloves, our big numbers did not indicate that it had found those niches yet.

 

Here four foxglove plants grow among slender mountain mint, sweet black-eyed Susan, slender gerardia, gray dogwood, foxglove beardtongue, saw-tooth sunflower, yellow wood sorrel, a few thin whisps of an oval sedge (perhaps Carex tenera), willow herb, Kentucky bluegrass, and a deer-eaten cream gentian. These low- and mid-conservative species comprise an attractive proto-savanna assemblage, but not a long-term stable community. With additional fire, time, and seeding it could develop into a quality prairie or savanna herb community. 

 

Here, five foxglove plants are growing with spotted Joe Pye weed, saw-tooth sunflower, sneezeweed, grass-leaved goldenrod, and narrow-leaved mountain mint. This is an even poorer-quality restoration at this point. No grasses or sedges. Few shorter-statured plants. No conservatives. Far from relatively stable. Our experience has been that such areas increase in quality over time, with regular burning and seed broadcast. If that happens here, will the resulting habitat continue to work for the eared false foxglove? 

Natural communities have evolved over millions of years to be “relatively stable.” They are characterized by highly-competitive, diverse, conservative plant species. They are now rare in the tallgrass region (and most of the temperate world). When, for biodiversity conservation, a formerly extirpated species is restored to a site, there’s a good chance that it could fail because of missing symbiotic pollinators, fungi, bacteria, and other associates. 

Somme Prairie Grove has the potential advantage that it’s partially original savanna and prairie remnants. Some crucial invertebrates, fungi, and other species may be surviving in small numbers. We found that when we broadcast seeds of the federal Endangered prairie white-fringed orchid, the fungus that it totally depends on was still here. A study by U.S. Fish & Wildlife found that very fungus in the restored plants' roots at Somme. Similarly, when we started restoring structure and quality to savanna with fire, thinning, and seeding, entomologist Ron Panzer found the formerly undetectable Edwards Hairstreak butterfly – a savanna specialist – to become the commonest hairstreak on the site. According to Dr. Panzer, it had likely been surviving here in small numbers and responded to restored habitat. 

 

Panzer’s research also found that larger, merely good-quality areas retained populations of remnant-dependent insects that no longer survived in some smaller sites that had been judged to be high-quality on the basis of conservative plants. Are the false foxgloves and other restored species here reestablishing relations with needed fungi or bacteria? We’d like to know.

 

Two periods of intensive care have both worked well for this species at Somme – but principally on the largely bare ground of young plantings. We broadcast vastly more seed in 2022 and 2023 than ever before – mostly in fair to good recovering communities. Thus, we expect to learn a lot more in 2024. 

 

The restoration of the Somme Prairie Grove black-soil savannas is testing a hypothesis. The number of plant species is up from about 250 when we started to about 500 now. How many of those species are here for the long term? Will these methods restore a substantial, high-quality, diverse, conservative community that has otherwise been lost? And might various now-rare species turn out to play a substantial roles? Or not? 

 

In areas with hundreds of big plants, cages somewhat protected some, but hundreds of other uncaged plants fared just fine last year. 

Some might argue that the eared false foxglove doesn’t even belong in the Somme savannas. Many modern sources refer to it as a prairie species. But one possible reason for that is that there’s so little savanna left to study. The standard old floras – Fernald (1950) and Gleason (1952) – both list its habitats as prairies and open woods. Like savannas, open woodlands aren’t what they used to be, but if a species lived in both prairies and woods, it seems likely that it inhabited the savannas too. Wilhelm and Rericha (2017) give today’s habitat only as prairie, but the prairie associates listed include slender gerardia, Canada rye, tall coreopsis, and cream gentian – species that may be less characteristic of prairie than of savanna. 

 

Ecologist Ken Klick with the Lake County Forest Preserves prepared a list of species that “may become extinct within Lake County Forest Preserves within the next decade.” The list included glade mallow (Napea dioica), bearded wheat grass (Elymus trachycaulus), Seneca snakeroot (Polygala senega), and awnless graceful sedge (Carex formosa) – all species that have dramatically increased in Somme’s savanna areas. Because of the way patches of shade and sun vary dynamically in savanna – as trees grow, blow down, burn, and die – it could be that savannas offer special advantages as annual species look for niches where they fit.  

 

Klick expressed concern that some of these species may depend on the restoration of natural conditions that are not today part of most natural areas management regimes. We hope that our “savanna restoration” experiments at Somme might help answer the questions Klick raised and inform biodiversity conservation efforts generally. 

 

As Reed Noss wrote in 1996, “If you think protecting species is hard, just wait until we try to protect whole ecosystems.” Many such efforts are now under way. Some fail. Some seem to be heading towards successes. We can learn from both.

 

References

 

Carter, Dan. Good discussions about similar issues in Wisconsin can be found at: https://prairiebotanist.com/ 

 

Fernald, M. L. Gray’s Manual of Botany. 1950

 

Gleason, H. A. The New Britton and Brown Illustrated Flora 1952 

 

NatureServe info is at: https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.148670/Agalinis_auriculata

Noss, Reed, Ecosystems as conservation targets. 1996. Trends in Ecology & Evolution 11(8):351

 

Ron Panzer, personal communication, 1992

 

Stuart Pimm, personal communication, 1995

Our previous report on this species at Somme can be found here. 

A good overall conservation summary for this false foxglove can be found at: https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=PDSCR01130

 

 

ENDNOTES

 

Endnote 1.

 

What have we learned so far about the eared false foxglove?

 

Although this species often does well where brush was cut, in most such places it goes away after a couple of years and doesn’t come back. Bare ground where brush was cut is not a long-term habitat here. We will not for much longer be cutting dense brush at Somme Prairie Grove. It’s almost gone. 

 

If we give this false foxglove “intensive care” (caging, seed harvest, and seed broadcast), it can increase exponentially. We try not to rely too much on our limited expertise on this plant. While we broadcast some of the seed we harvest in new areas that look similar to where the foxglove has prospered, we also add some of the seed to our wet-mesic prairie and savanna seed mixes, so that it ends up in more "random" places. Often it emerges where we've planted the seed mixes in areas that "didn't look right" for this plant ... and fails to emerge in the areas that seemed "just right." 

 

Little tubular vole exclusion cages can help. Taller ones (10” to 12") work better than shorter ones (6”), but do not work all the time. Indeed, the voles sometimes climb over the top, then down to the bottom, then section stems, gradually pulling seed heads down. (Tying the seeds to the tops of cages prevents the voles from pulling them down.)

 

If we just wait for the seeds to spread, mostly they don’t spread very far.

 

We haven’t yet found this species doing well in any of the higher-quality associations at Somme. But then again, it’s a wet-mesic species, and we have very little wet-mesic high quality so far. (Recovery seems faster in our mesic and drier communities, perhaps because these burn more frequently under today's conditions.) Our goal is to establish high-quality prairie, savanna, and woodland throughout the site, as much as possible. 

 

This false foxglove does well at the edges of saw-tooth sunflower patches – not in the centers of them.

 

Two species of parasitic morning glory called dodder (Cuscuta grovonii and glomerata) seem to help the hemi-parasitic false foxglove. Dodder is a valuable "regulator species" that can dramatically set back over-dense patches of saw-tooth sunflower, slender mountain mint, and others. Where dodder thinned out such species, it seemed to leave intermixed plants of the foxglove mostly alone. 

 

A highly-respected botanical research institution, at our request, recommended scientific experiments to help us better understand our eared false foxgloves. The recommended protocols included carefully counting numbers of seeds and placing them in a wide variety of plots and transects in spots carefully chosen to represent a variety of factors. All seeds were placed in areas of relatively stable vegetation, sometimes near existing false foxglove patches in similar vegetation, but not within them. It was a lot of work, compared to what we usually do. The educational result was that not a single false foxglove emerged from any of the seeds planted for these experiments. We learned that you can’t just pick small areas for it and seed there. It could be that this species, in areas of competition, requires special conditions that we don’t recognize. Thus, we seem to find it succeeding among competitive vegetation only here and there, and only when we broadcast seed to the wind over wide areas.  

 

Endnote 2

 

What do we want to learn?

 

Does the fact that the voles seem to eat all plants of this species in many places reflect a) some artifact of the modern world, b) this species lack of adaptation to this site, or most parts of this site c) the fact that we broadcast its seeds in the wrong places?  Perhaps this foxglove doesn’t normally survive to produce seed in thriving grassland but instead in thin areas where brush recently burned back or bison trampled a lot. Such areas represent both less competition from other plants and less cover for voles.) 

 

Voles tend to get it just as the seeds start to set. Are there approaches to spraying stinky vole repellent that would work better than caging? The repellent does seem to work. Would it also repel pollinators if we spray it too early? 

 

Might this species do better in some other specialized niche – that we’re not recognizing and where we are thus not broadcasting seed?

 

Will it in time adjust and show up sporadically (perhaps in places where brush has burned back or where dodder, fungus or some other stress has reduced competing vegetation)? 

 

Does it not belong here, in the relatively stable communities we are striving to restore? Will it fade out and be gone from Somme without a lot of "horticultural" work, that would violate our current long-term goals here?  

 

Are there better approaches through which we could continue to pamper it for a while and at the same time do a better job in facilitating better adaptation to existing or emerging niches? It’s a globally rare savanna plant that could be another Somme Prairie Grove success story. Or failure story? 

 

Acknowledgements

Thanks to Christos Economou and Eriko Kojima for many helpful edits. 

Graphs by Linda Masters

Most "intensive care" work on the eared false foxglove in recent years has been done by Eriko Kojima and Sai Ramakrishna. 

 

Prescribed burns and overall supervision credit goes to the Cook County Forest Preserves staff including burn manager Steven Ochab and ecologist Anna Braum. .