Mistake? (or Experiment?): mixing wild leeks

Will these aggressive wide-leaved leeks blot out the trilliums? Professor Jones suggested, "maybe."

Given the incipient-at-best state of true ecological restoration, it can be difficult to tell the difference between a mistake and an experiment.

Perhaps this example started as ignorance, then seemed a mistake, and now is an experiment[1]?

Amateur botanist Justin Burdick might have saved us Somme stewards a lot of trouble when, in 1877, he sent a letter to Asa Gray at the Harvard College herbarium, explaining that the Midwest had two different wild leeks. But Gray’s Botany didn’t accept his suggestion. 

Somewhat paraphrasing Doug Ladd: rare natural ecosystems can’t be successfully managed by people who see the vegetation as “a green blur.”[2] You need to know the species. We mostly didn’t start out as botanists, but many of us have tried to learn plants sufficiently to be good stewards.

I’ve recently been struck by one mistake I had long made. We thought our one species of leek had two subspecies. I’d treated those two as “a green blur.” Varieties? Oh please! How much difference did it make? For Somme and the North Branch generally, we gathered seeds, dumped them into mixes, and broadcast them across the recovering (we hoped) ecosystem. 

We’ll consider what long-term difference that might make. But first, let’s review the history of whether there are two distinct types of leeks, possibly with different roles to play in the ecosystem. Our bible, Swink and Wilhelm[3], long told us that we had just one species of wild leek. Yes, there were two “varieties” or “races,” but my brain was already burdened by too many species – and resisted dealing with races. 

Embarrassingly, looking back, it turns out to be easy to tell those two apart. 

The narrow-leaved leek is the all bluish-green clump on the left.
The wide-leaved leek is the taller clump on the right with the distinctive reddish stems. 

The “narrow leek” (now called Allium burdickii) has overall narrower leaves that are green or whitish all the way to the base. 

The “wide leek” (now called Allium tricoccum), has longer, wider leaves with narrow red stems. 

These two species have many other distinct differences. For example, narrow leek blooms in early June. Wide leek blooms in July through mid-August[4]. 

Many people have never seen leek flowers. Although leeks are one of the most prominent plants in the spring flora of rich woodlands, they never seem to have flowers. Their foliage lushes up the background of our May flower shows – but then fades away and is gone. Unexpectedly then, in June, when the first leek flowers come up, they’re all by themselves. Just a flower head on a naked stalk. 

My second thoughts about leeks began with the big new Somme Woods East restoration effort in 2014. I began to notice that the leeks in the lowlands, farthest east, seeded to have those wide leaves and red stems. The leeks in the uplands (that is, up on the moraine) were those narrow-leaved bluish ones. Should we stewards, if they were naturally separated, mix these two up when we seeded?[5]

To test my concern, I checked Somme Prairie Grove (one of the planet’s first attempts at true restoration of a black-soil oak savanna) and found that the wide leek seemed to occur only where we had planted it in our seed mixes. The narrow leek was the only one in the least-degraded, most-remnant (and unplanted) areas. Oh oh! Maybe we only wanted the narrow here.

So, somewhat uneasily in 2016, for the first time we started separating the two leek “varieties” and broadcasting their seeds only in the kinds of areas where we’d found them. In Somme Woods, we restricted the narrow-leaved seeds to the high ground to the west and the wide-leaved seeds to the low ground to the east. Our new decision to treat these “varieties” differently was supported by the arrival in 2017 of the new Flora of the Chicago Region[6] – which treated the two as separate species, Allium tricoccum and Allium burdickii.

Now I looked ruefully at the mixed leeks in the beautiful Vestal Grove where so much good restoration had so long been done. Had we made a big mistake? Or did we launch an unintentional experiment? Would the wrong leek be a negative for the ecosystem, or would the competition of better adapted species drive it out? Or what?

But more angst bubbled as I now researched these varieties/species. A 1979 article by Professor Almut Jones was especially troubling [7]. She described the narrow leek as a “play well with others” kind of species – the sort we most want to restore in the early stages of a restoration. Of the wide leek, she wrote, “Populations of Allium tricoccum usually form extensive colonies. Frequently the bulbs are so densely spaced that other vegetation can hardly penetrate the stands.” By contrast, she writes, “the plants of Allium burdickii occur in scattered small clumps of from three to about a dozen individuals. The stands are integrated with and surrounded by the dense herbaceous forest vegetation prevalent at the height of spring.”

I now remembered that the place where I’d first been struck by and learned tricoccum was just such a monoculture. It was on the new Somme East trail. This stand-out patch attracted all the photographers every spring, because the leeks were so lush, so early in spring. No one payed so close attention that they knew whether little else would grow there as the season progressed. Did we have to worry about this thuggery happening at Vestal Grove and the other under-restoration areas at Somme?

Wide-leaved leek - so dense that little else survives. Had we planted a pest?

Narrow-leaved leek “plays well with others.” Here its bluish leaves are scattered in a rich community with white trillium and geranium (starting to flower) and leaves of hepatica, early meadow rue, trout lily, wood anemone, elm-leaved goldenrod, Short's aster, and many sedges.  

Is the narrow-leaved leek more typical of diversity and quality? Are they an evolutionary adventure where one species divided into two for some reason. What can we learn from their differences?

In 1953, Hanes[8] compared the habitats of the two types this way: “The species (tricoccum) is found generally in marshy habitats whereas the variety (burdickii) prefers upland woods.” Hmmm. In this region, we don’t find leeks in marshy habitats.  

The Flora of the Chicago Region by Wilhelm and Rericha (W&R) was published in 2017. W&R characterized both leeks as species of mesic habitats[9], and as to their quality, the W&R judgement seems quite the opposite of what concerned us in the Jones paper. W&R gave narrow leek a fairly high-quality coefficient of 7 – but the wide leek rated an impressive 9. As we study plants, assessments change. The 1994 Swink & Wilhelm (S&W) had rated narrow a 6 and wide a 7 – so W&R is upgrading them both.)   

The often-elusive goal of true restoration is a community with diverse conservative species – including many species with “Coefficients of Conservatism” in the 6 to 10 range. Do either of these leek species help or hinder the recovery of such ecosystem health? Our concern about the “thug potential” of the wide leek is not allayed by W&R’s 9 rating. We’re trying to learn to restore highly degraded oak woodlands at a time when few or no very high quality ones still exist. Do W&R’s rating of 9 for the wide-leaved reflect its ecology in Michigan and Indiana, where it grows in non-fire-dependent and otherwise very different beech-maple forests? Did Jones find the wide-leaved to be a "thug" because it crowded out all else in degenerating oak woodlands in the absence of burns? The great John Curtis[10] had pointed out as early as 1959 that, under fire suppression, not only maples but also such oak-woods conservatives as trillium, bellwort, and blue cohosh could wipe out the original diversity of oak woodlands. 

The 1994 S&W had seen wide leek as common “especially in our eastern sector (Indiana and Michigan). They listed associates like sugar maple, beech, Dutchman’s breeches and squirrel corn – but no oaks. They characterized narrow leek as “even more common” – with associates including white oak.

The 2017 W&R finds both species sometimes associated with bur and white oak – and with each other. Is it possible that the wide is increasing and replacing the narrow (and other spring flora) during the current degrading of most sites because of decreasing light – as the much-shadier maples replace the less-dense-canopied oaks?

The scientific sampling at many sites that has been going on for decades could help answer such questions (if the sampling distinguished between the two varieties or species). It will be interesting to re-look at previous sampling and study future results under various conditions. Anyone have sampling results that would help clarify any of this?

As for the Somme area, when I double-checked as I wrote this paper, I found yet more surprises. The nearby Chipilly Woods (which until recently had many much higher quality areas) seems to have only the narrow. But in another high quality woods, McDonnald Woods, two moraines to the east of us, Jim Steffen reports large amounts of both, especially the wide leek[11].

Another surprise: The best quality remnant in Somme Woods is between a horse trail and Dundee Road, where decades of cutting brush (for no ecological reason – just to keep the horse trail open and prevent trees from growing out over the road) maintained a bit more light. Here such quality species as hepatica, shining bedstraw, two trilliums, Penn sedge, elm-leaved and zigzag goldenrods, and many others thrive densely together. But this area, in the lowland to the east of the moraine, is where I’d come to expect the wide leek. When I checked for this report, it has the narrow leek only. Indeed, when I kept my eyes open for it, I found no wide leeks anywhere except for two patches of less than an acre each – in the hundreds of acres of potential Somme habitat. The two patches were both fairly close to the decayed foundations of a long-abandoned pioneers’ house. Is it possible that the settlers brought along and planted the wide leeks from farther east? They taste better and are easier to harvest.

I hadn’t considered the narrow leek to be an especially conservative plant, but when I checked, I now found that it hugged the edges of that horse trail closely, with many other conservative species. Back even a few feet from the trail edge, under ancient bur and white oaks, but now in the gloom of invading young maples, the flora survivors consisted almost entirely of carpets of trout lily, spring beauty, and false mermaid. As I searched back and forth to test my hypothesis that the leek now closely hugged the trail, I was surprised to discover yet another, nearly disappeared house foundation. And here were numerous leeks – of both kinds. Another puzzle. 

I’m now less worried about the wide leek in Vestal Grove. I found a few plants of it apparently growing spontaneously in an area I was sure we hadn't planted. Perhaps we didn’t introduce it; perhaps it was there all along. I am, however, no less interested in watching how it interacts with the other species over time. In Somme Woods, should we continue to limit planting the seeds of the two leek species to areas where they already occur? If an area is too degraded to have any surviving leeks or much else, should we plant only the works-well-with-others narrow leek? Or should be plant both and watch them fight it out? Or try to replicate the distribution we found when we started? Or forget about special treatment for the watched leeks and focus our limited decision-making capacities on other questions? This is how good restoration works. We know that we have to make the best decisions we can without knowing all the facts we wished we had. We'll reflect, seek input, discuss, alter plans if needed, and carry on. 

One wrinkle we’ll probably never fully understand is the complex of impacts by previous forest preserve land managers, foragers (and planters?) of medicinal and edible plants, farmers that managed the land before the preserves bought it, and native peoples who managed it before them. We’d like to know more. But we don’t need to wait before we proceed with the best stewardship we can.

The real fundamental challenge is to save nature – to preserve the ongoing life of the communities and species that are making their “last stands” here. Millions of years of evolution have continuity here. If the losses of diversity can be reversed for the full suite of plant species, that’s enough to give us some confidence – as we continue to restore as best we can sustainable natural conditions for the plants, invertebrates, fungi, bacteria, algae, and so much of the ecosystem that the planet may turn out to need. So much resource and potential. So much beauty and mystery. 

Special bonus: Author’s Messages

Message to people thinking about maybe becoming stewards

You are very much needed. You can do a lot of good without being an expert. You can learn as much as you want, as you go. You can also quickly become expert in a few specialties and add to the science that conservation depends on. (The ongoing recovery at Somme is a great opportunity for many people to learn and contribute – and we could use so many more hands and minds.)

Message to advocates

Please help us get the message out. A hideous extinction event is under way, right here, now. The ongoing losses at so many sites are so sad, despite many good (and some not so good) increasing efforts recently. 

Message to all stewards

Your mission is noble (without the despotic sense). Your mission is holy (in the best senses). Your mission preserves and restores beauty, health, and the future possibilities for the human and biotic communities of the Earth. Creation thanks you.

Message to dedicated, committed staff

Your mission is noble and holy. Thank you for your work and what you have to put up with, as you preserve and restore beauty, health, and the future possibilities for the human and biotic communities of the Earth. Creation thanks you.

Message to just good, honest staff

Even if you don’t quite get the conservation passion, and perhaps your next job will be in sales, or hospitality, or as a poet … your good work is appreciated. 

Endnotes

[1]Restoration takes many forms, and is not easy to understand. Restoring health to a somewhat degraded remnant is very different than starting with a corn field. Similarly, original high-quality natural areas are so much richer than "from-scratch" restorations. There’s almost no comparison. Or, if one was to compare, to quote Jerry Sullivan from memory, as best I can, “If the natural area was Einstein, the restoration would be some sort of Frankenstein monster, staggering down the street with wires hanging out of its neck.” Since Jerry published that line (apropos of Mayor Daley’s claim that he could with impunity tear down and re-build a natural forest to make way for a new airport, saying, “This is Chicago; we can do anything.”), some restorations have advanced toward the somewhat better. But there’s still “no comparison” in most cases. 

And, sadly, there's no such thing as a remnant high-quality prairie or oak woodland that's large enough for animal populations and most ecological processes. So we start most of our best conservation initiatives by including both remnant and to-be-restored components. 

Should the challenging state of our ignorance of the whole ecosystem make stewards pessimistic about their restoration efforts? I'll argue, no. True ecosystem restoration is very hard, but to strive for it is to strive for the same kind of “miracle” that resulted in antibiotics, the wheel, and the computer. Ecosystem conservation and restoration can be planet-changing. Success or failure will ultimately make the difference in whether humanity is to live (or die) on a planet of weeds and cockroaches – or whether we can, given our other mistakes and over-indulgences, learn to save most species in ways that retain potential and health of the Earth. 

[2]Doug Ladd has long been admired as one of the most respected of the Nature Conservancy natural area managers. He retired in 2017. He was Missouri Director of Science and Stewardship (a title I once proudly bore for Illinois). I encourage conservationists to read his parting wisdom, published: https://nature.mdc.mo.gov/sites/default/files/downloads/NANewsletter2017%20-%20web.pdf

Note that Ladd writes mostly about very high-quality natural areas. But on rich soils there are no very high quality savannas or woodlands (except possibly on Walpole Island, or some military bases?). (There are "high-quality plant communities" – but a community that is too small for most animals is not a high quality natural ecosystem.) So we restore as best we can. Assumption: if we save all the plants, the animal species will be saved as well, at least if the site is large enough. 

Superficially, Ladd is doing the opposite of restoration. Indeed, a major point of his article cited above is that ecosystems are not resilient and do not recover once they are severely compromised. He reminds us powerfully of need for the very best management for the very best areas.

[3]Swink and Wilhelm’s Plants of the Chicago Region(1994) told us that these two “varieties” were both common, with the classic wide-leaved leek being a little more conservative (C = 7), being found with such classy associates as yellow trout lily (C = 8) and large flowered trillium (C = 8). The other narrow-leaved “variety” was a tad less conservative (C = 6) with none of those classy associates, being found with merely with white trout lily (C = 5) and the red trillium (C = 5), although it did score with sharp-lobed hepatica (C = 6).   

[4]This note discusses common names and then expands on bloom dates and other differences between these species. 

Common names for plants are not “official.” You can make up your own. The scientific name is subject to many rules and is codified in books and scientific articles. As Allium burdickii was not recognized by most people as a species, it did not have a common name in wildflower books. Now that many botanists are recognizing it as a species, some apply common names. The excellent Illinois Wildflowers calls it “narrow-leaved wild leek.” The U.S. Dept. of Agriculture’s website calls it “narrowleaf wild leek.” Swink and Wilhelm gave it no common name. Wilhelm and Rericha call it “Chicago leek.” This last name is a great one, locally, as this leek appears to be the plant that the Chicago region was named after. But for a plant that can be found from Maine to the Dakotas and south to the Carolinas, the Chicago name is probably not going to win out. Some botanists continue to call Allium tricoccum“wild leek” – but then we don’t know whether they’re referring to the traditional “both species or races together” or to the new “split out” wide-leaved one only. So, that’s confusing. Also, common names have a way of simplifying, for convenience, so for now I’m going to go with “narrow” and “wide.” 

Compared to wide leek, the leaves of narrow leek emerge later, but the flowers emerge earlier and for a shorter period of time. In the Chicago region the narrow leek blooms from June 8^th to July 2^nd (25 days). The wide leek blooms from June 19^th to August 16^th (59 days) according to Wilhelm and Rericha. Flower stems are comparatively short and stand straight up for the narrow leek  – and twice as tall and angled to the side for the wide leek. 

According to Illinois Wildflowers, narrow-leaved leek has 10 - 20 flowers per head while wide-leaved has 20 - 40. According to Wilhelm and Rericha, narrow has “rarely more than 18” and wide has “30 or more.” 

[5]If you haven’t followed the Somme East initiative, you might be interested to know that it is one of the planet’s first attempts to truly restore a rich oak woodland. As may be generally true of the highly fire-dependent oak woodlands on rich soils, there are few or no “very high quality” remnants. There was no very-high ("Grade A") quality remnant part of Somme Woods. There were some smaller areas that could be high quality ("Grade B") as to the herb community, though small. Our challenge has been to drastically reduce shade and broadcast seed (locally gathered) of the hundreds of plant species (grasses, wildflowers, and shrubs) that have been lost (to grazing, shade, drainage, fragmentation, and whatever). It is our hope or “hypothesis” that sufficient original fungi, bacteria, and invertebrates are holding on such that much of the woods ecosystem may recover as a restored whole. 

[6]In Wilhelm and Rericha’s Flora of the Chicago Region, the two leeks are treated as separate species. Associate lists are somewhat different from those in Swink and Wilhelm.

[7]Jones, Almut G. (1979). A Study of Wild Leek, and the Recognition of Allium burdickii (Liliaceae). Systematic Botany. Vol. 4. No. 1, Potawatomi 29-43. More complete quotes from Jones:

“Populations of Allium tricoccum usually form extensive colonies. Frequently the bulbs are so densely spaced that other vegetation can hardly penetrate the stands. This becomes apparent about the middle of May when the leaves have died. The maroon-colored scapes and inflorescence buds do not contrast with the color of the forest floor, and the colonies give the appearance of denuded patches of ground …” 

“By contrast, the plants of Allium burdickii occur in scattered small clumps of from three to about a dozen individuals. The stands are integrated with and surrounded by dense herbaceous forest vegetation …”

“… vegetative reproduction is the more common mode of population growth and survival in Allium tricoccum… In A. burdickii, the situation is probably reversed. Seed production is at least as important as vegetative reproduction…”

Two photos above illustrate Jones' point: the narrow-leaved leek seems not to have the dominating tendencies sometimes seen with the wide-leaved. But only parts of that Somme East patch are thuggishly "monocultural." Other parts look like the photo below:

Here wide-leaved leek grows with white (large flowered) trillium, cut-leaved toothwort, and spring beauty. 

One feature of this much-talked-about patch is that it has an unusually dense population of trilliums. White trilliums tend to get badly eaten down by deer and in nearby areas are more scattered and smaller. Do the leeks somehow protect the trilliums? 

[8]The earliest academic papers I found that distinguished between the two leeks (giving credit to Justin Burdick for his initial 1877 notice) were published in 1946 (Hanes and Ownbey) and 1953 (Hanes). In 1946 the two forms were tentatively called merely Race A and Race B. By 1953 Hanes was bravely calling narrow leak a named variety (Allium tricoccum var. Burdickii). It wasn’t until her 1979 article that Jones took the final plunge and proposed the narrow-leaved leek as a separate species.

A species can divide into two for many complexes of reasons. Usually subpopulations need to be separated geographically for such "speciation" to proceed. But both species of leeks occur over most of the range of the species. In this case, it appears that a key component in the history was the genetic isolation of two populations by flowering dates. Perhaps the wide-leaved individuals adapted more to shade from trees in denser maple and beech forests. Perhaps the narrow-leaved adapted to lower light levels from dense herb-layer vegetation (in the thinner canopies of fire-dependent oak forests and savannas). Perhaps totally other limitations and opportunities ruled. This species would be fun to study in depth.

[9]If you have patience for yet more detail on the wetness issue, the Somme “signature patch” of wide leeks is indeed in a wetter area than where we typically find the narrow ones. But the other species present are species of mesic habitats (e.g. toothwort and white trillium), certainly not “marshy.” W&R support Chase to the degree that, although they characterize wide leek as a "mesic" species, they place narrow leek in "dry-mesic to mesic." To make it more complicated, parts of Somme Woods east of the moraine are definitely well-drained enough to be called mesic, and the other patch of wide leek occupies one of these drier, clearly mesic areas. Thus, we may have been falsely seeing the difference between the two as “up on the drier moraine” (narrow leek) and “down on the moister relative flats” (wide leek). The W&R characterization is in keeping with the comment by Chase that “If both grow in the same locality the variety occupies the higher ground.” The “variety” – of course – is burdickii.

[10]Curtis, John. The Vegetation of Wisconsin. 1959. On page 148, Curtis described the death of an oak forest: "Due to complete fire protection ... the mesic trees began to spread out, basswood going first ... followed by an almost solid wall of young sugar maples. ... groundlayer ... oak plants gradually died out. ... unusual combinations of dominance because of the lack of competition. Thus the heart of the maple island had high densities of blue cohosh (Caulophyllum thalictroides), bellwort (Uvularia grandiflora), and Gleason's trillium (Trillium gleasoni), which rarely attain such proportions in a typical mesic forest." Are those monocultures of wide leek a temporary component of some such successional process (perhaps in most current cases "artificial succession" rather than "natural succession")? 

[11]Jim Steffen, long time manager of the Chicago Botanic Garden’s fine MacDonald Woods, reports that: “We have always had both tricoccum and A. t. burdickii.  Generally it seems like the tricoccum occurs in large dense patches while the burdickii is more scattered with fewer individuals.  I would say the tricoccum is much more abundant here than burdickii.  I would also say that burdickii seems to be somewhat drier growing than tricoccum.  Burdickii flowers about two weeks earlier than tricoccum.  I think they both occur in similar wooded habitats although burdickii might have a preference for more open canopy, but that could be my imagination.  Our largest patch of tricoccum (perhaps 3 acres or more) is in a mesic site dominated by white and red oak along with Isopyrum, Caulophyllum, and Menispermum.” Those last three species are false rue anemone, blue cohosh, (which we do not find at Somme) and moonseed. 



Last photo and end:

Wild leek flower cluster, with daddy longlegs. Having 23 flowers (and long, angled, red-based stem - not visible in this photo) it seems to be the wide-leaved leek. This photo by Lisa Culp Musgrave.