Hypoxis Experiment Succeeds – in the Ecosystem

Yellow stargrass (Hypoxis hirsuta) is a conservative prairie and savanna species. Once ubiquitous, it is now largely limited to remnant ecosystems. When we planted over 150 mature, dormant roots (corms) in Somme Prairie Grove in 2013, our expectations were modest. Experience taught us that small, conservative species like Hypoxis often fail to thrive in restoration.

There is reason to believe that some little, obscure species may have outsize influence on overall ecosystem function (see Endnote 1). If so, Hypoxis may be one of those key species. 

Our original hypotheses included the hope that, if our transplants of this "high quality" species could survive in a degraded restoration area, in time they would self-seed into their surroundings. For seven years, this hypothesis seemed not to have been borne out. 

In 2022, we have learned of Hypoxis:

• It matured to flowering from seed after 8 growing seasons. 
• It reproduced best among diverse, not-rank, conservative associates.
• Reproduction often occurred many feet away from the original plant, indicating it happened by seed, not from corm division.
• In rank vegetation, many planted corms survived and flowered but did not reproduce.
• Individual Hypoxis plants can thrive for at least 15 years.

We will briefly discuss below why some of these lessons in the ecosystem, side-by-side with others, could add up to something “big.” We will also argue that this sort of “messy” approach to ecosystem research can sometimes be more useful to day-to-day conservation than more "hard scientific” efforts. 

A higher-quality portion of “Transect L” in 2022. Yellow flags mark where Hypoxis had been planted on each side of the path - and this year the centers of the fifteen plots that we searched for new plants.

But first, the sweet facts.

• 2013: we inoculated much of Somme Prairie Grove with mature corms of Hypoxis. For more details on the beginning of this experiment, click here. 
• 2019: we located 148 of those plants, where we planted them, in transects, many along footpaths, ten meters apart. But we found no evidence of reproduction, either vegetative or from seed.
• 2020: we rechecked 10 plots and found five additional original plants in bloom, but still with no reproduction.
• 2022: we re-sampled those 10 plus another 5 plots and found that 13 of them now "all at once" showed blooming reproduction, with from 1 to 15 new plants each.

Since seed is being dispersed from these plants every year, we therefore have reasons to expect that this formerly-ubiquitous, conservative prairie and savanna species (see Endnote 2) will reproduce massively, in years and decades ahead. It’s another step in understanding ecosystem recovery. 

Perhaps these “discoveries” shouldn’t have been a surprise. But they feel glorious. It’s so good to know new details … with numbers … and to consider the implications. 

Below are the 2019 and 2020 results of our first monitoring. 

Table 1. 

Survival and Reproduction among Planted Hypoxis Corms -

Six and Seven Years After Planting

A portion of Transect L – 10 plots. (In 2020, we only seem to have bothered to monitor ten plots; for more plots monitored later, see Table 2, below.)

Plot	2019 orig	2019 repro	2020 orig	2020 repro
1	1	0	2	0
2	0	0	2	0
3	1	0	2	0
4	2	0	2	0
5	2	0	2	0
6	1	0	1	0
7	2	0	1	0
8	1	0	1	0
9	0	0	1	0
10	2	0	2	0
T	12	0	16	0

In four plots, there were one or two more Hypoxis in 2020 than in 2019. At Plot 7, there was one fewer. It’s clear that some plants survived that had not been found in 2019 (probably not flowering) when we conducted our first follow-up survey. 

A minor lesson here seems to be that not every plant blooms every year (or perhaps just not when we're sampling). For our monitoring, we only recorded blooming plants. It’s not easy to find a little grass-like plant among all the others when it’s not blooming. Some of us wasted time trying. Not worth it. We have stuff to do. 

We monitored again this year, 2022. Why bother? It happened that, while walking the trails, looking for other things, I got the impression that I was seeing more Hypoxis than previously. We then monitored Transect L (the only transect for which I could quickly find the prior data). Of the 15 plots we quickly located, we only bothered to have monitored 10 in 2020. Does this all seem sloppy? Yes, it does. But we actually believe it most productive for us to work in this sometimes-sloppy way – to be discussed in more detail in a later post, “Is This Science?” 

If Table 1 was the set-up, Table 2 is the punch line. “Suddenly” – nine years after the corms were planted – reproduction was up from 0 to 63. These “new” plants have likely been slowly growing to maturity over the years, without wanting to use what resources they’d amassed in their growing corms for flowers and seeds. The fact that so many plants were now flowering for the first time suggests that there were no other nearby plants spreading seeds here. That is, these new plants came from first seeds produced by the originals that were planted in 2013.

New Hypoxis in bloom along the transect

Below, for the full 15 plots of Transect L, are the 2019 results compared to 2022. For more details about the plantings, transects, and plots, see Endnote 4.   

Table 2. Survival and Reproduction among Planted Hypoxis Corms -

Nine Years Later

Transect L – 15 plots

2019 and 2022 Reproduction and Structure

Plot	2019 orig	2019  repro	2022 orig	2022 repro	Structure
1	1	0	1	0	Rank
2	0	0	2	2	Rank
3	1	0	2	1	Mostly Rank
4	2	0	1	1	Mostly Rank
5	2	0	1	3	Diverse
6	1	0	2	6	Diverse
7	2	0	1	12	Diverse, short, sparce
8	1	0	2	5	Mixed
9	0	0	2	2	Rank
10	2	0	2	15	Diverse, low
11	0	0	2	0	Rank
12	1	0	2	2	Mixed
13	0	0	1	1	Rank
14	1	0	2	4	Mixed
15	-	-	2	9	Diverse
T	14	0	25	63

 

Lessons from Table 2: 

• The numbers of surviving original transplants, located by their flowers, continues to increase.
• Most reproduction occurred in five plots (6, 7, 8, 10, and 15). That is, 47 out of 63 new plants were in those five plots. Or 74% of the reproduction was in 33% of the plots.
• The plots showing most reproduction were the more diverse and characterized by shorter and more conservative plants.  
• One possible implication of this study is that, if we have Hypoxis seed to sow, we might not want to waste it in rank new restoration areas. 

The plots in which we counted the new plants were ten meters long and eight meters wide. That is, these plots were centered on the original transplants and extended five meters in both directions for approximately four meters on either side of the path – a distance in which we could easily see those bright little yellow flowers. Thus each plot was 80 meters square.

We first tried to assess the habitat quality in the 15 plots by various objective means, none of which seemed practical. Thus the assessments above are a matter of judgment. The following photos and captions may provide a sense of how I made the judgements. The captions list conservatives present as well as the diversity that includes somewhat-conservative species. 

Transplant surviving in a Rank and Non-diverse plot shown below:

Rank. A solid stand of mountain mint is also heavily dominated by dense big bluestem grass. (Notice the short lengths of stems, sectioned by voles last summer, that cover the ground in this spring photo). By mid-summer, such areas may be too dark for Hypoxis to do well. Over time, with burning, such areas may become diverse as a result of broadcast seed ... or just seed that blows in from nearby diverse areas. 

New plant in diverse plot:

Here the young Hypoxis grows among conservative prairie violet, leadplant, and wild quinine along with rattlesnake master, compass plant, Culver’s root, hairy green sedge (Cx hirsutella), big bluestem, and others.

New plants in diverse plot:

Hypoxis reproducing among conservative violet wood sorrel, small skullcap, and Leiberg’s panic grass along with rattlesnake master, woodland sunflower, gray dogwood, heath aster, and others. 

New plants, in a diverse area, broader view:

 At least 14 Hypoxis recruits blooming among diverse shooting star, prairie dropseed, rattlesnake master, woodland sunflower, Carolina rose, tall coreopsis, and others. 

We were also interested in whether reproduction was vegetative or by seed, and if by seed, how far the seeds would be effectively spread. The table below shows distances of new plants from the original planted corms.

Table 3. Distances of new plants from original transplants

#	2022  repro	Distances of new plants from original transplants
1	0
2	1	4”
3	2	4’, 6’
4	1	8’
5	3	2’, 7’, 7’
6	6	2”, 8”, 2’, 3’, 5’, 10’
7	5	2’, 2’, 3’, 4’, 4’
8	5	4’, 5’, 10’, 10’, 11’
9	2	3’, 6’
10	0
11	15	3”, 4,”, 5”, 10”, 1’, 1’, 2’, 2’, 2’, 3’, 3’, 4’, 5’, 5’, 6’, 9’, 10’
12	0
13	1	6”
14	4	7”, 9”, 10”, 4’
15	9	6”, 4’, 4’, 5’, 6’, 6’, 7’, 8’, 8’

Of 63 plants, only 11 are less than one foot from the originals. 52 were 2 to 10 feet away. (The seeds of this species clearly have ways to get around. It is known that the seeds of some plant species have special features that motivate ants to disperse them. No doubt others have other 'creative' ways.)

Plots 2 through 10 are in prairie-like, very open savanna. Other transects in former (and now-under-restoration) prairie areas seem to be doing similarly. Plots 13 through 15 are in shadier, but still open  savanna. Corms planted in woodland area have apparently not survived. For notes about prairie, savanna, and woodland results, see Endnote 2. For cautions about the data, see Endnote 3. 

Discussion and Possible Implications

Let’s stipulate that the biodiversity of the tallgrass region may be important. Much of the world’s food is grown here. Much good science talent is here. The genetic alleles most significant for heading off “crop pandemics” or to improve nutrition or to combat climate change may lie among the biota of our nature preserves. 

The critical gene pools are not just of plants but also of bacteria, fungi, invertebrates, and much other biota. Despite the valiant efforts of preserve staff and volunteer stewards, even some of our best and most important nature preserves are losing plant species and other biota. Insufficient resources are focused on biodiversity, and even if many times the current amount can be obtained, the need will still vastly outstrip our funding and abilities. We need to become more expert and effective. 

Many of our best areas are too small. Species will not survive vicissitudes and adapt to climate and other changes unless their numbers and acreages increase. As Dr. Ron Panzer has shown for invertebrates, it is likely that for breadth of gene pools of the biota generally – that larger and more diverse preserves would contribute much that doesn’t survive in the smallest, highest-quality areas. For that, we need wise restoration or recovery efforts. Such work will be much facilitated as our expertise in ecosystem first-aid improves. Practitioners should keep records and write up results. 

Endnotes

Endnote 1: Small 

Ecosystem “restorations” are typically pathetically inferior to millenia-old original “remnants.” In comparison, the restorations tend to look “rank” and “wrong.” “Prairie restorations” usually lack most of the plant species of original prairies. If those species are seeded in, they typically don’t survive. For example, most prairie and savanna restorations have few if any of the little species: small skullcap, prairie violet, Mead’s sedge, violet wood sorrel, and Hypoxis. Of course, many classic big species are also typically absent: prairie lily, heart-leaved Alexanders, prairie parsley, prairie white-fringed orchid, prairie gentian, etc. etc. It could be that many of the species missing are those that reproduce best in the matrix that includes the smalls. (Of course, all the conservative species may benefit in various ways from all the others.) This study of Hypoxis looks into just one little species, but it suggests implications. 

 

Endnote 2: Prairie, Savanna, and Woodland.

As we use the terms in this post, very open savanna (or “Prairie” – as it is named in our seed mixes) has no tree shade and includes all prairie plant species. 

Open savanna (as it is named in our seed mixes) has tree shade for one or a few hours a day and most prairie species, but also a substantial part of the vegetation consists of such shade-associated species as carrion flower, pale Indian plantain, meadow parsnip (Thaspium), veiny wild pea, and spreading dogbane. In these areas there tends to be a greater than normal preponderance of such prairie-and-savanna species as Culver’s root, big bluestem, wild quinine, and early goldenrod.

Closed savanna (as it is named in our seed mixes) has much dappled shade. Here the warm-season “prairie” grasses, though present, are less the principal fuel than are oak leaves and various sedges. Characteristic species may include rue anemone, wood pea (Lathyrus ochroleucus), broad-leaved panic grass, violet bush clover, and wild columbine.

Woodland is an important community that has not to date been well considered for its significance to biodiversity conservation. Preliminarily I’d be tempted to propose that in this region, characteristic species may include Carolina vetch, upright bindweed, Hypoxis, robin's plantain, wood rush, and wood pea.  Another lesson of this experiment so far is that planted Hypoxis corms did not survive in our woodland plots. It’s likely that the problem was that these plots were in woodland restoration areas too new and rank and too dark. Hypoxis does survive in some remnant woodlands; indeed it is a major plant in the highest-quality woodland we have ever seen – the subject of a dramatic upcoming post. 

  

Endnote 3: Caution about the data

Let’s separate what we know from what we reasonably suspect. For example, we do not know as a general principle that Hypoxis reproduces flowering new adult plants after eight growing seasons. We know that this method of monitoring picked up the mature new plants in the nineth year, in these soils, among these associated species, under this burn regime, in this period of weather and climate, at this latitude and longitude. Results might be somewhat or highly different elsewhere. But we know that these results are promising for restoration of this conservative plant and provide suggestive data. 

Endnote 4: Details about the transects and plots, if you're interested

Most transects, including this one, were set up by pacing off intervals and placing a flag in the ground at every ten meters. We measured by pacing instead of a meter tape because it's quicker. Some transects followed existing paths (also for convenience), but some crossed areas without paths, starting at one easy-to-locate tree and ending at another. At each flag, the crew would plant one corm about a half-meter to the right and one to the left. Actually, they'd kneel down at the flag and dig a hole for the corm a convenient bending distance (about 0.5 meters) to the right and the left. 

We defined the plots in which we looked for reproduction as extending from a given planting point half way to the next. Thus the plots were ten meters long, centered on the planted corms. The plots extended about 4 meters to each side of the transect, as that was the distance over which we could see and count the blooming plants. We had not been confident that the transects would be easily re-located. But it did turn out to be easy, as we found no Hypoxis along these transects in 2019 and 2020 except for the lonely pair or single blooming plant at the ten meter intervals. 

A subsequent post will raise other cautions, concerns, and possibilities. 

 

Two Final Photos

Here a lone Hypoxis has emerged among the pussytoes. Low, conservative plant species (some of them hemi-parasites) will likely help maintain the diversity of the recovering prairie and savanna here. These species include Hypoxis, bastard toadflax, Penn sedge, Mead’s sedge, small skullcap, and pussytoes. 

In this area, Hypoxis was apparently planted by seed four decades ago. It is now so thick that it could be said to be the matrix that other conservative species are best seeded into for successful reproduction. This density may be more than would be seen flowering in a very high-quality prairie. More discussion on this in subsequent post. 

References

Many more details about this experiment are given in this earlier post. 

An example of dense Hypoxis in high-quality white oak woodland can be found in a fine post by Dan Carter. The site he reports on will be the subject of a future post here. 

 

Acknowledgements

Hundreds of people deserve thanks for their contributions to this work. Volunteer stewards and Cook County Forest Preserve staff have nurtured and restored Somme Prairie Grove since 1980. Sai Ramakrishna, Jeanne Dunning, and others planted the original 148 plus corms. Eriko Kojima helped find and monitor the transects in 2019 and 2022. Christos Economou, Adam Rux, Kathy Garness and Eriko Kojima contributed proofing and edits. When the word “I” is used in this post, the narrative reflects the experiences or judgements of Stephen Packard.