The Pulse of Curiosity: an exploration of an endangered aster

by Noah Hornak

To let one’s curiosity run loose can be likened to traveling on a helm-less ship succumbed to the natural chaos as it navigates you through drunken waves and shifting winds. It’s only when you relinquish control and allow passion and open-mindedness to be the driving forces that you eventually reach land safely. I believe that in order to expand one's breadth of knowledge and experience, you must often take trips like these blind to any particular destination and develop a humble trust towards curiosity. This can be said for any interest in life, but I find it especially applicable to the study of our natural world. 

This fall I was invited to monitor and study one of Illinois’s threatened woodland species, Forked Aster (Eurybia furcata, formerly Aster furcatus). Impacted heavily by habitat loss, fragmentation, fire suppression, and invasive species, this handsome white-flowered aster has declined precipitously throughout the Midwest. To make matters more dire, according to the Center for Plant Conservation, E. furcata is self-incompatible: it is an obligate out-crosser unable to produce viable seed when pollinated by genetically similar individuals. This theoretically results in “mate limitation”, a situation where over time a population dies out from lack of reproduction because it never receives pollen from a genetically distinct individual.

Eurybia furcata (Forked Aster)

At Somme Woods in Northbrook, IL, multiple populations of E. furcata can be found growing within the 265 acre Oak Woodland-Savanna matrix. The subpopulation I monitored had been tracked previously in 2017 and 2019 but had not been sampled or analyzed since then.

Having never collected monitoring data before, I was excited to study how this imperiled aster has been doing for the previous five years and to explore approaches to monitoring plant populations. As with anything we try to do for the first time, we can conceive of how we expect things to play out, but oftentimes the methods or tools we bring to the table turn out to not be as effective as we expected. Fortunately, I was joined by Stephen Packard in this process who supported me as both mentor and catalyst to help me learn his techniques about how to capture data effectively.

The Data

The transect runs down the center of a brook and starts in line with a large Northern Red Oak neighboring a Swamp White Oak of the same size. The transect follows the brook’s meandering course until reaching the finish line 146 meters to the east between two charismatically large Swamp White Oaks. Data was taken for all flowering stems within 5 meters north and south of the brook’s banks making the transect’s total area about 1,800 square meters.

Outlined in green is the transect following the middle fork of South Brook, with Dundee Road to the south.

This subpopulation of E. furcata was established through the efforts of stewards within the Chicagoland area collecting and broadcasting seed methodically along the South Brook. Care was taken to collect this seed from multiple remnant populations in order to introduce a locally adapted and genetically diverse mix into Somme Woods.

E. furcata spreads through underground rhizomes, which immediately posed a challenge when trying to determine one individual plant from another when two clonal individuals grow close together. The solution we decided to follow would be to collect data based on “clumps”, or groups of individuals which had blended together and were thus indistinguishable. Utilizing this approach we counted a total of 71 clumps, an increase from 62 found in 2019 and 49 in 2017. More clumps being formed each year suggests that the existing individuals within the population are successfully reproducing.

	2017	2019	2024
Total Clumps	49	62	71
Clumps Found on Northern Side of Brook	N/A	39	47
Clumps Found on Southern Side of Brook	N/A	23	24

Given a steady and growing increase in the total number of clumps along the brook, perhaps the population has a sufficiently wide genetic diversity of individuals resulting in successful cross-pollination by insects. This seems to be a relatively uncommon situation among other Midwestern E. furcata populations that appear to be struggling. 

	2019	2024
Total Flowering Stems	263 (N: 135, S: 128)	922 (N: 523, S: 399)
Average Flowering Stems/Clump	4.24	12.99

 Flowering Stems Data Table; N = flowering stems found on northern side of brook, S = flowering stems found on southern side of brook

Within each clump, we counted the number of flowering stems to help gauge the size and health of individual clumps. We saw a substantial increase in the number of flowering stems. In 2024, these totaled 922 with an average of 12.9 flowering stems per clump compared to a 2019 total of 263 flowering stems and an average 4.2 flowering stems per clump. This suggests that either each plant is successfully growing clonally through underground rhizomes or perhaps individuals are indeed reproducing sexually and new plants are germinating close to their parent plants.

The difficulty in distinguishing individual plants from one another highlights an opportunity for genetic testing to paint a clearer picture. According to a 2021 study conducted by Chicago Botanic Garden researchers, E. furcata can form clonal patches of 100 or more stems (Gavin-Smyth et al. 2021). This leads me to believe much of the rise we see in flowering stems is due to individuals reproducing asexually.

By capturing location data for each clump we were able to relocate clumps that were previously recorded as well as distinguish newly found clumps that were not recorded in 2019. We found 33 new clumps had developed since 2019 with an average of 13.6 flowering stems per new clump.

	2019 - 2024
New Clumps	33 (N: 19, S: 14)
Average Flowering Stems/New Clump	13.65
Clumps Not Found	12

 N = clumps found on northern side of brook, S = clumps found on southern side of brook

There were 12 clumps present in 2019 that were not found in 2024. There are several threats to E. furcata at Somme Woods including but not limited to deer-browsing, shading out by trees and/or tall vegetation such as tall goldenrod (Solidago canadensis/altissima), and  genetic limitations. Perhaps the clumps simply died happily of old age, at the end of a natural lifespan. Recording field data is also subject to mistakes - it could simply be that we happened to miss some of them.

Deer and other herbivores like to eat the upper leaves and flowers 

Tall/Canada Goldenrod and patches of briars (Rubus spp.) can be seen shading out and outcompeting many native plants including Forked Aster

When comparing the data on individual clumps recorded in 2019 with the 2024 data, we see an increase in the number of flowering stems by an average of 9.3. The majority (33 out of the 38) of the historic clumps found increased in number of flowering stems with only 5 decreasing in flowering stems.

One metric we collected that hadn’t been done previously was the dimensions of each clump. In 2024, clumps had an average width of 0.9 meters and an average length of 1.4 meters. Being as this was the first year recording dimensions of clumps, this data will be more helpful as the population is monitored regularly. According to Center For Plant Conservation, the rhizomes can extend up to 40 cm from the parent plant; this was unbeknownst to me at the time of recording data and may be taken into account next year to help alleviate some of the problem of trying to distinguish between individuals.

	2019	2024
Average Distance From Brook (meters)	2.99 (N: 3.27, S: 2.56)	1.67 (N: 2.13, S: 0.9)

N = clumps on northern side of brook, S = clumps on southern side of brook

The brook serves as the fulcrum of the transect and so by measuring the distance from the edge of each clump to the bank of the brook, we were able to see that historically tracked clumps are expanding in the direction of the brook as well as producing new clumps nearer to the brook. In 2019, the average distance of a clump from the brook was 2.9 meters. In 2024, that average distance decreased to 1.6 meters. 

Several clumps measured in 2019 were seen to have extended closer to the bank of the brook. An obvious conclusion might be that the plants have an affinity toward the more moist soil of the brook. However taking into account another transect of E. furcata in Somme Woods where most of the plants were found growing in upland areas suggests that there are other factors that may be at play here. In previous years, only the distance from the bank was measured; with future monitoring that includes dimensions of clumps, we may learn that the clumps are also expanding away from the brook. Some other components that could be affecting the growth patterns of individuals in relation to the distance from the brook include canopy cover, associates, soil microbiome, and levels of disturbance. 

Also interesting is the difference of clumps’ distance from the brook in relation to whether the clump is growing north or south of the brook. Clumps growing north of the brook averaged 2.1 meters away from the brook while south clumps averaged 0.9 meters away from the brook. In general, the northern side of the brook tends to be more open with more dappled light reaching the vegetation, resulting from restoration thinning of large trees years ago. On the north side, there may be less pressure on individuals to grow towards the brook because there is more light available, as opposed to on the south side of the brook where many a Quercus rubra (Red Oak), Tilia americana (American Basswood) and other trees stand tall.

The southern side of the brook also tends to have sparser vegetation and larger patches of bare dirt than the northern side which essentially has a continuous strip of the threatened Carex bromoides, other sedges, and wet-mesic forbs.

“Clump” of E. furcata (Source: https://www.inaturalist.org/observations/14423647)

By collecting data on clump dimensions, we are able to determine distances between clumps. We measured an average distance of 4.06 meters between clumps with a relatively large difference between clumps located north of the brook (average distance of 2.6 meters between clumps) and south of the brook (average distance of 6.7 meters between clumps). The south side of the brook having more distance found between clumps isn’t surprising considering there simply aren’t as many plants as on the north side of the brook for the reasons hypothesized above. Looking at how this measurement changes over time in conjunction with ongoing tree thinning along the brook will be interesting to study. 

Looking Forward

Some things I’d like to do next year when monitoring this population again to provide more accurate and supplemental data are: 

●      Collect data on number of plants that set seed 

●      Make note of associate species composition to look at how Eurybia competes with different associates 

●      Make note of number of non-flowering stems 

●      Visit South Brook after spring thaw to gain a better understanding of the hydrology of the brook

●      Participate in other E. furcata transect measurements within Somme Woods and other sites to compare how others are collecting their data and making calls about how to differentiate clumps from one another 

●      Use GIS and GPS device to accurately capture location data of clumps 

●      Make note of data collected amongst areas thinned and where Rubus patches are cleared and treated to gauge restoration effect on Eurybia 

Final Thoughts

I kick myself in the butt for neglecting to pay much attention in what science classes I took throughout school. Having a strong foundation of knowledge for me to reference would be very helpful in my restoration practices and studies such as this monitoring. Yet I’m not sure I would have retained much of what my science teacher taught me about phenotypic plasticity or genetic drift even had I aced all those tests and studied hard because I lacked a convincing motive to want to learn these things. 

Nowadays I find myself wanting to learn as much as I can about the natural world and all its processes and constituents. Since counting that first Eurybia patch along South Brook, my brain has bombarded me with many questions, some of which I’ve answered and others that leave me wanting to explore further. For instance, the concept of self-incompatible breeding systems and how an individual can prevent germination of pollen deposited from a different individual sharing a common S-allele. Stuff like this is still racking my brain and has humbly brought to my attention through stumbling through scientific papers my need for the foundational understanding of genetics. I’ve since been working my way through YouTube lectures and methodically reading a cell biology and genetics textbook.

Recently, I’ve been welcomed among the Somme Woods volunteer stewards to help manage the same area of the E. furcata transect. This has granted me a lot to think about in terms of how to restore this habitat and what role forked aster plays in a biodiverse woodland system. Being a part of a learning community such as the one at Somme Woods and many more across the Chicagoland area is invaluable for someone with an itch of curiosity and wanting to play a part in restoring our natural areas. 

I hope for this to be a call for others to give way to your curiosities and allow them the space and energy they need to bring about fruitful experiences and new found knowledge. There will always be many more questions than answers but by many of us making efforts to expand our scope of focus and periodically budget energy towards different domains and fields, I believe our collective understanding of ecology will be strengthened.

This is not to say that hyper-focused study is not important. It’s what has pushed the pinnacles of scientific discovery forward. However, there is value in developing a holistic view from which we look upon the world. There’s always a time and place where the scope of one’s studies will fluctuate between a level of fixation in one specific arena and one of a broader stroke where a vantage point of a bigger picture is needed. Anecdotally speaking, the more I embrace and ride out this natural fluidity of successive ideas and topics, the more I sense my curiosity being satisfied, yet continually growing with time, and providing me with new perspectives and foundational grounds from which to stand on. 

I’ve always marveled at the people whom I’ve met or read about who can reassuringly be labeled “naturalists”. Removing the romanticism attached with the idea of a “naturalist”, these are the people who have seemed to cultivate true wisdom through taking the pursuit of curiosity to its fullest extent and who have the ability to not only look at things on an organismal biologic scale but who take a step back and understand phenomena on a grander, more eco-systematic method. This kind of understanding only comes from constantly asking questions and purposefully seeking to put oneself in situations of uncertainty conducive to learning opportunities. 

Simply put, I believe we need more curious “naturalists” in this world. Everyone possesses these traits albeit across a wide gradient and perhaps what I’m trying to get at is: I both encourage and plea that more of us give weight to our curiosities and give ourselves permission to explore different avenues and dimensions of this world and to continually challenge baselines of knowledge by embracing new opportunities as they are presented without being afraid of changing courses from time to time as you never know what discoveries and experiences will come out of it.

References

Gavin-Smyth N, Kramer AT, Urbina-Casanova R, Vitt P, Fant JB (2021) Genetic rescue reduces mate limitation in a threatened, clonal, and self-incompatible plant species.Restoration Ecology, 29, e13458