Questions on the Mt. Cuba Coneflower Trials and Pollinators

2/1/2021

I've written and erased a version of this post several times the last week trying to get the ideas down right -- this is a complex topic. Ultimately, I just want to ask questions and express some concerns I've not seen addressed elsewhere in my professional circle and see where it leads us (hopefully, somewhere helpful).

I'll say two things first: 1) I'd rather see a garden of coneflower cultivars than lawn or daylilies and 2) I have intense respect for the work Mt. Cuba does. We'd be in the dark without Mt. Cuba, yet this trial is just one preliminary, necessary step forward and not a final clear-cut answer.

If you don't know, the Echinacea trial evaluated coneflowers in the mid-Atlantic based primarily on garden performance -- how the plants grew, looked, and lasted. However, one issue regarding pollinators really stands out to me: the trial noted the number of adult pollinators visiting the blooms of cultivars, and used this to say which would be of best value to adult pollinators. This doesn't fly (pun intended) for a few reasons:

1) What species were visiting the blooms and how were they using the blooms? Until we have these answers we can't even begin to understand value or benefit or what's occurring in the ecosystem. There are nuances to nectar and pollen use, as well as life cycles and habits of various pollinator species, that help us get a much more complete picture of what's going on. I'd also like to know what pollinator species were showing floral fidelity.

2) What is the chemical and nutritional make up of the nectar and pollen? What amino acids (nectar) are being provided and what's the protein content (pollen)? Sure, it may very well be a cultivar is providing something a straight species can't -- or vice versa. There's also the nuance of these things being affected by climate, ecoregion, etc.

3) What's happening to UV markings on petals that plants use to communicate with adult pollinators? What about aromas? What about electromagnetic fields?

4) Tallamy's study a few years back on woody cultivar larval hosts indicated that changes to leaf color (leaf color effects larval host ability), specifically purple, greatly reduces larvae -- whereas variegation doesn't. Dr. Annie White looked at adult pollinators and flowers (species and cultivars) on herbaceous perennials and found mixed results on her preliminary study, but species plants had the edge. We know double-flowered coneflowers are terrible. However, I still wonder if, by selecting over and over for one trait (bloom color), we're creating a loss of genetic diversity that may translate into increased chances for something to be amiss in the foliage for larvae.

There's still so much we don't understand, especially on a region by region basis. Certainly, I also don't want to see these cultivars placed anywhere near remnant ecosystems that harbor straight species Echinacea, either (which would be my house). To fully understand the above issues will require a significant amount of resources we probably won't ever have; but I think it's as problematic for folks to say something like "see, when we manipulate plants it's all good and may even be better for wildlife" as it is for someone like me to say "we should always use straight species natives no matter what everywhere, every time, period."

And I still believe we can't have this conversation without also considering how we manipulate plants for commercial gain and / or to please the aesthetic desire of one dominate species, along with the messy ethical implications behind human supremacy that readily colonizes plant culture. But I wrote a book on that.

32 Comments

Amanda nugent

2/6/2021 08:06:37 am

This is such an important area of study! Now that I know the importance of host plants that has become my biggest area of focus in my garden practices, but sometimes it so hard to find straight species. I wish there was some way to really know of a cultivar was ok or not. Thank you for sharing!

Benjamin Vogt

2/6/2021 09:42:57 am

There's certainly going to be genetic variation (local ecotype) even in straight species natives, so there's always this variability and diversity -- which helps plant evolve and adapt. That being said, I really haven't found it hard to find non cultivars: so many mom and pop natives in every state, and there's Izel Native Plants, which works with native wholesalers in the eastern half of the country to get native plugs to you.

Cecilia

2/10/2021 08:32:45 am

Amanda, you might look into the wintersow method of seed starting, the one that uses milk jugs and other reused containers to start seeds outdoors. It's ideally suited to native plants and I've used it with great success for several years. Native plant seeds are not hard to get, either from seed companies like Prairie Moon or Everwilde Farms, or from local groups like WildOnes. There are FB page and websites to help you learn to winter sow. And it's fun!

Deborah Schroeder

2/7/2021 07:39:48 am

I have Echinacea purpurea straight species in my garden along with a few cultivars (Ruby Star, Cheyenne Spirit, Pow Wow). There is much more insect activity at the straight species plants - it’s obvious the insects prefer this food source. The straight species is beautiful and fragrant - perplexes me as to why we need all these Echinacea cultivars. But, if the cultivars get more people interested in native plants, that is a good thing. A ‘Fragrant Angel’ Echinacea cultivar is much, much better than an eco-dead lily.

Benjamin

2/7/2021 08:26:01 am

Someone will have to prove to me that cultivars are a gateway to straight species. What's going to motivate you to seek out a "lesser" straight species and stop collecting plants like decorator plates? Maybe they can help with getting folks to consider ecosystem function and larger conservation issues, I don't know, but couldn't ANY plant do that? I think cultivars are rife with human privilege and being exploited by a capitalist society that sees value in nature only as a source of extraction -- for energy or for pleasure, and for one species.

Francis Groeters

2/7/2021 12:05:52 pm

Humans are inquisitive, creative, and yes acquisitive. Sometimes those traits result in computer screens to read web blogs and sometimes they give us orange coneflowers. Acquisitiveness of course is pretty high on the list of traits favored by evolution - all species, one way or another, are designed to exploit their environment. Hedonism is simply an extension of the acquisitiveness favored by natural selection. Good luck eliminating the hedonism that prompts people to value decorator plates, orange coneflowers, computers, web blogs and on-line classes - it’s the result of a few hundred thousand years of evolution. But using the web to inform people that Echinacea ‘Kismet Orange’ is a darn good plant for pollinators (as Mt Cuba has done) and the orange coneflower they should be planting if they so desire one - that’s taking advantage of hedonism rather than simply ranting about it.

Benjamin

2/7/2021 12:20:34 pm

Francis -- Thanks for the well wishes. I'm well on my way with my book, A New Garden Ethic, and the next one forthcoming in 2022, Prairie Up. We all have to contribute our voice and find our calling -- I have found mine, especially through the study of reconciliation ecology, deep ecology, and ecofeminism. Be well.

Francis Groeters

2/7/2021 10:17:22 am

You are obviously a very thoughtful person, so I’m not surprised at your response to the Mt Cuba trials, but I’m afraid you are guilty of over-thinking.
The trial provides a simple metric of pollinator attractiveness of different Echinacea cultivars. That’s it. Yes there are 7000 unanswered questions. But so what? That doesn’t diminish the value of the trial and so your comment that “this doesn’t fly” is flat out incorrect.
It’s sort of analogous to the concept of “fitness” in evolutionary biology. Count the number of offspring produced - that’s all that matters. Yes, there are a myriad of underlying reasons why one individual produces more offspring than another, but they don’t matter. Other than as a purely academic exercise.
The fact that straight species Echinacea purpurea is #2 in attractiveness is a good indication that the metric used in the trial is a good one. What the study allows us to do is pick cultivars that are close to E. purpurea in their attractiveness to pollinators. Should a gardener plant Echinacea ‘Sunrise’ to attract pollinators? Heck no - it’s at the bottom of the list. ‘Ruby Star’? Heck yes. It’s about the same as straight species. Which shouldn’t be surprising since it really isn’t very far removed from being a straight species.

Benjamin

2/7/2021 11:56:15 am

Francis -- Thank you for adding your perspective! I appreciate it. Sure, I may be overthinking it, or I could simply be asking us to think one study does not prove a rule without replication -- especially when it's a regional study and has way more to consider. We could simply shrug and say, "works for me" and happily move on, or we can keep pushing as natural inquiry would ask of us. So while part of me wants to yes, absolutely to you, the researcher and critical thinker in me wants to know more -- which is why this study is so beneficial; it starts a deeper conversation we need to have in a time of mass extinction and climate change caused by a dominate species. (We haven't even touched on the ethical implications that end my original post, and that are delved into in my book.)

Francis Groeters

2/7/2021 12:09:43 pm

You draw conclusions based on the data you have on hand. That's all you can do. When more data becomes available those conclusions can be modified. But to suggest that no action be taken or conclusions drawn because all information is not available is pointless.

Benjamin

2/7/2021 12:17:49 pm

Francis -- You seem to be drawing those same conclusions, just from a different angle. Maybe we both need to be more careful here? Still, I don't think anyone can say that a coneflower (no matter a species, selection, or hybrid) is beneficial to pollinators simply by counting how many total adults are visiting -- that is a very, very narrow proof of concept and quite reductive. The study Mt. Cuba did is a solid beginning point, and to acknowledge that reality does not diminish it: science is built on replication and exploring new facets, asking questions and building upon those questions,. In fact, all human endeavor is that.

Francis Groeters

2/7/2021 12:40:25 pm

"I don't think anyone can say that a coneflower (no matter a species, selection, or hybrid) is beneficial to pollinators simply by counting how many total adults are visiting". Really?????? You are letting the pollinators themselves inform you what they consider valuable. You'd prefer that Mt Cuba measured protein content of the pollen? Then you'd be claiming that they need to see if the differences in protein content translate into actual pollinator visits. No, you're wrong here. Sure it's possible that pollinator visits don't translate one-to-one into reproductive success. But that becomes your burden to demonstrate. Until you can do that you go with Occam's Razor. The simplest explanation holds. Pollinator visit counts are a good metric for pollinator value of the plants.

Benjamin

2/7/2021 01:10:14 pm

I don't think I'm wrong. They did not count the insect SPECIES using the coneflowers, so we have no idea who's using the flowers and how and when. And this is still just one facet of what's occurring. Saying X number of flying things visited a plant is not a scientific conclusion I'd get behind on any level; it's like saying because 100 people are eating at restaurant X and 80 are eating at restaurant Y, than the former must be better. Why are they going there? What is the quality of the food? Etc etc etc.

Francis Groeters

2/7/2021 04:53:14 pm

The data in the Mt Cuba study are internally consistent. One would expect double coneflowers to receive few pollinator visits. They indeed receive few. One would expect straight species E. purpurea to be among the most visited. It indeed is. This internal consistency suggests the results of the study are broadly trustworthy and I believe the study is useful in helping gardeners choose cultivars to include in their landscape that are attractive - certainly in a relative sense - to pollinators.

It would be surprising if floral visitation is not a good proxy measure for plant value for pollinators. Sure some plants try to fool pollinators into visiting but provide no reward - orchids are a well-known example. But generally speaking, bees and other pollinators simply don’t spend time visiting flowers that provide them with little or no reward.

That is a fundamental fact that you need to explain away - and it’s not obvious to me how any of the 4 reasons you provided to doubt the study do so.

Benjamin

2/7/2021 05:10:55 pm

You're totally ignoring everything I've laid out that needs further research by defending your point of view with abstract qualifiers like "it would be surprising" and "generally." My kid would eat cake every night for dinner if I let him -- it tastes great but isn't as good for him as fruit and vegetables. If we don't know anything about the nectar and pollen, we do not have a complete picture. I also did not say the study wasn't useful, but I have said many, many times now that it is a helpful starting point to get us going. We don't have any clear answer yet -- I might suggest picking up books by Heather Holm or exploring the research of Jarrod Fowler to see the critical nuances of pollinator interaction that the Mt. Cuba study is missing. And we're STILL just talking about adult insects here: not bugs, not larvae, and we're not gaining any new insight about what native vs. exotic bees are using the plants and how. This is really, really important and another study will need to be done and then replicated.

Francis Groeters

2/7/2021 05:31:53 pm

I’m ignoring everything that you’ve laid out because it’s all irrelevant. Let me give you an example. When Rhus glabra is blooming it attracts a greater diversity of insects than any other plant that I’ve ever observed. I’ve never identified a single species that is visiting the flowers. I’ve never analyzed the nutritional content of the pollen or nectar. What would be the relevance of those things or floral UV markings or electormagnetic fields to drawing the conclusion that Rhus glabra is a great pollinator plant based on floral visitation?

The Mt Cuba study says that there are a few cultivars of Echinacea purpurea that are as attractive to pollinators as the straight species and that there are a whole bunch that aren’t. It’s a simple observation that you seem to be desperate to obfuscate. Not sure why.

Benjamin

2/7/2021 05:34:24 pm

You're a hoot, Francis. Thanks for the conversation. I guess we'll have to agree to disagree here.

Francis Groeters

2/8/2021 08:31:06 am

Here’s a study in the Journal of Applied Entomology: Bee visitation rates to cultivated sunflowers increase with the amount and accessibility of nectar sugars (https://onlinelibrary.wiley.com/doi/abs/10.1111/jen.12375). They found that “Both wild bee and honey bee visits significantly increased with nectar sugar amount and decreased with corolla length, but appeared unaffected by nectar sugar composition.”
Oh look, here’s another study in the Journal of Economic Entomology: Effect of nectar composition and nectar concentration on honey bee (Hymenoptera: Apidae) visitations to hybrid onion flowers (https://pubmed.ncbi.nlm.nih.gov/10985033/. They found that “The average amount of nectar produced by both the umbels and the individual florets was significantly positively correlated with the number of bee visits. Our results suggest that selection for flowers with high nectar production may lead to a higher rate of pollination of the onion seed crop”

I could go on an on. Pollinators visit flowers that provide rewards and avoid flowers that don’t. It’s a fundamental tenet which underlies Pollination Ecology and Foraging Behavior. For a lengthy but accessible lay treatment of the topic I suggest Bernd Heinrich’s Bumblebee Economics.

The most parsimonious interpretation of the Mt Cuba Study, as I stated above, is that there are a few cultivars of Echinacea purpurea that are as attractive to pollinators as straight species Echinacea purpurea and that there are a whole bunch that aren’t. The information is useful in guiding cultivar choice by gardeners who want to support pollinators. Hand-waving about electromagnetic fields simply obfuscates the value of that information.

Benjamin Vogt

2/8/2021 09:03:26 am

Francis -- First, thank you for the links. I'll disregard the honey bee study since they are not a conservation issue. Similarly, I could link to studies (or just say read A New Garden Ethic or my next book, where many of the studies are referenced), but I'm not sure where that would get us because I'm not going to convince you at this point, and you're not going to convince me (and I don't need to convince you). Second, I'll be even less open to your perspective if you maintain a snarky, passive-aggressive tone. I'd prefer to have a productive, empowering, constructive, professional conversation with you -- as do those reading our exchange. Finally, it really would be useful to explore how plants (and their flowers) communicate with pollinators -- that's not obfuscation, just inquiry and the scientific method, which propels us further. I'm beginning to wonder what more is at play here (do you have an investment in this study? Why are the original perspectives so triggering?). Regardless, we can't simply keep going round and round. You're welcome to have the last word if you like.

Francis Groeters

2/8/2021 09:20:19 am

Benjamin - I think your blog is an important one and it has great influence. So when I saw you post that the Mt Cuba study “simply doesn’t fly” then engage in over the top/irrelevant hand-waving as the reason it “doesn’t fly” I was prompted to respond. The study has clear value. That’s what you should have concentrated on and the take home message to your readers should have been that the study can be used to make appropriate choices of Echinacea cultivars if they choose to plant cultivars rather than the straight species. Since you seem to have an anathema toward cultivars it’s not surprising that you tried to find a way to suggest that the results of the study can’t be trusted. That’s being intellectually dishonest. That’s my last word.

James McGee

2/8/2021 05:51:44 pm

What I don’t understand is why either of you care if someone buys and plants the newest Echinacea cultivar on the market. I’m sure you both know how these cultivars are created. Millions of Echinacea are planted in a field and one or two will end up with some anomaly that is different (compact growth, double flowers, more fragrance, different flower color, etc.) This anomaly makes the cultivar interesting to collectors. These collectors buy a cultivar, usually several, for a very high price. After being planted in the garden, unless they are sterile, the Echinacea cultivars produce seeds. The seeds grow. Then the expensive Echinacea cultivars are overtaken by the wild type genetics through natural selection. The only way to prevent this is through continuous diligent work. The seed heads, or any seedlings that grow, must be removed. Anyone who has grown Echinacea cultivars knows this problem. Echinacea tends to only live for several years. Since most gardens typically get neglected, the domestication is lost and if anything remains it is the wild type. The only issue I see is people are spending lots of money on cultivars that won’t last very long. You can tell people to not waste their money, but good luck stopping them.

Francis Groeters

2/8/2021 06:46:12 pm

It’s true that some cultivars of many different species of plant arise spontaneously in commercial growers production stock or in homeowner’s gardens. But many are specifically created through hybridization and/or careful breeding programs. In the case of Echinacea, orange, red and yellow cultivars were created by intentional hybridizing of E. purpurea and E. paradoxa. I’ve found E. paradoxa to be a short-lived species and it seems as though most of its hybrid offspring are similarly short-lived. However, many cultivars are as long lived as the species, especially ones that really aren’t very different from straight species plants like ‘Ruby Star’ and other pink/purple varieties. And breeders are also aware of the problem that cultivars are short-lived and are trying to select for greater longevity.

So, to the extent that some cultivars are relatively long lived, and perhaps becoming more so, if they are inferior to straight species plants with respect to the ecosystem services they provide (in the context of the Mt Cuba study being discussed here, the services are sustenance of pollinators) it would be better for the health of the ecosystem if only straight species plants were used by gardeners. This is the reason Benjamin is strongly opposed to cultivars and I certainly agree with him in this regard.

But we don’t live in a perfect world do we? No, we live in a world in which people, quite naturally, want to acquire unique plants that they find visually pleasing. In that reality, the primary point I was trying to make in my posts is that if people are going to plant cultivars - and as you say, good luck stopping them - the information provided by the Mt Cuba study allows gardeners who say really, really want an orange coneflower but still want to support pollinators to be able to pick a cultivar that does so.

Or consider white coneflowers. If a gardener really, really wants a white coneflower, the Mt Cuba study reveals that the best choice for doing so but maintaining a healthy ecosystem is ‘Fragrant Angel.’ Indeed it’s as attractive to pollinators as straight species E. purpurea. The variety ‘Happy Star’ only attracted about half as many pollinators. So if the goal is to get plants into gardeners hands that are both attractive and functional from an ecological perspective, the Mt Cuba study provides excellent guidance.

You make a very good point as well, that if cultivars are generally inferior to straight species with respect to vigor, longevity, attractiveness to pollinators and reproductive success, natural selection will fairly quickly eliminate their genes from the population. So why fear that they will overrun wild populations? I’m sure Benjamin has an answer to that query.

Derek Yarnell link

2/8/2021 08:51:38 pm

Frances and James, for me personally I am concerned about the proliferation of cultivars at the expense of ecologic productivity, even if most cultivars would eventually disappear. There will always be more behind them. And without a switch in consumer mindset we will never get 'caught up' on rewilding our urban and suburban spaces which is what we need to do in order to help biodiversity. I like to picture a future where we have normalized plant 'productivity' (in addition to native status), although this is a layer of complexity most gardeners may not be ready for and industry is certainly not ready to bring to the table. While I may be on a native planting spree in my own yard at the moment, I think the answer can't lie in native plants alone. The biodiversity crisis is so large we need all the allies we can get, including folks who will not chose native plants but might chose the most beneficial cultivar.

James McGee

2/9/2021 12:09:22 am

Frances, you should be nicer to Benjamin. The guy is obviously really hard on himself with all his ethics, beliefs, and such. It is no wonder he is highly critical. All that baggage he carries around must be a lot to bare.

I have grown Echinacea hybrids crossed with E. paradoxa. My E. ‘tomato soup’ and E. ‘twilight’ only lasted a few years. My E. ‘harvest moon’ and E. ‘sunset’ have lasted much longer. It is not surprising that Echinacea hybrids with E. paradoxa genetics would tend to not be long lived in my area (Chicago Region). Our flora lists lots of southern or western waifs. Most of these waifs appear along railroad tracks. However, they mostly last for only a short period before disappearing. Likewise, hybrids tend to be unstable. Occasionally, there are hybrid swarms that appear stable when both parents are present. A good example is Gentiana alba and Gentiana andrewsii hybrids. However, this is more the exception than the rule. The seedlings from Echinacea hybrids that have grown in my garden may maintain some of the traits of the parents like flower size or growth form. However, of all the seedlings that have grown around my Echinacea paradoxa hybrids only one did not have the typical color of wild type E. purpurea.

My experience has been that the Mount Cuba trials are extremely useful in selecting cultivars. Their earlier results convinced me to try E. ‘pica bella’ in my garden. This cultivar has become my favorite purple coneflower. It is the shape that makes it so great for a garden rather than an unusual color. I grew E. ‘fragrant angel’ for years before I accidentally dug it up and gave it away thinking it was an unwanted seedling. I can attest that the flowers of E. ‘fragrant angel’ are large and fragrant which is probably what makes them attractive to pollinators. However, as often is the case with larger-than-normal flower size the cost is having less flowers and a plant that is not as vigorous as other selections. In the end, my experience has been that I must continually remove seedlings that grow so the expensive hybrids I purchased do not get overtaken by plants with the flower color of wild type E. purpurea.

Another problem with the Echinacea hybrids is the plants that have yellow, orange, or red flowers can change to have purple flowers. Sucking insects can transfer genes between plants. To prevent this, I try to keep the different cultivars separate from each other by a good distance in the garden. However, this is difficult considering the seedlings from yellow, orange or red cultivars are almost all the color of wild type E. purpurea. I know that eventually the color that makes these cultivars desirable will be lost, and I will only have wild type color flowers.

Francis Groeters

2/9/2021 07:02:00 am

Point taken James. Occasionally in the midst of arguments one gets a little too strident in defense of their position.

Benjamin - my apologies for morphing into Cujo the killer blog poster. Let's bury the hatchet. And let me acknowledge Benjamin that your basic criticism that there are other things that we would like to know about Echinacea cultivars is a good one. For example, another major system service that plants provide is seeds for birds and seed-eating insects. How do cultivars do in this regard? In fact I’m going to write to Mt Cuba and suggest that any further study of Echinacea or other genera of plants include measurements of seed set.

James - one skepticism for you - “Sucking insects can transfer genes between plants.” Don’t think so. I know of no evidence that true bugs (insects with sucking mouthparts) are capable of gene transfer. Yes, they transfer disease organisms. One reason for example that it’s recommended that wild raspberries are removed from home raspberry plantings else aphids will transfer detrimental viruses from wild plants to garden ones. And yes, geneticists engineer viruses to carry a particular gene and insert it into a target organism, so perhaps that’s where you get the thought that true bugs can change coneflower flower color by transferring genes. However, I know of no evidence that viruses on their own can take up portions of their host genome and transfer those genes into another plant host. Do you have a reference to a scientific study demonstrating this?

James McGee

2/9/2021 12:03:51 pm

The necessity to plant Echinacea cultivars away from each other was told to me by staff at Platt Hill Nursery. This was the nursery from which I purchased my plants. They have a display garden that is nicely labelled and planted with what they sell including Echinacea cultivars. In the display garden the flower color of some of the cultivars has changed to the magneta typical of wild type Echinacea purpurea. The process by which this occurs is actually quite interesting. The entire plant of these yellow or orange coneflowers does not change flower color all at once. Sometimes, part of these plants has the flowers of the cultivar and another part of the same plant has the flower color of wild type Echinacea. Typically, the part of the plant that has the flower color of wild type Echinacea is adjacent to a magneta colored cultivar.

Sucking insects are ubiquitous. I know the genes would need some way of being transferred between plants and this seems to be the likely vector. The gene that can be transferred between bacteria and some protozoa, plants, and animals are called plasmids. There is a lot of research available on the subject that can be accessed easily by doing a keyword search on the internet. Enjoy your search.

Francis Groeters

2/11/2021 08:16:42 am

I think it’s worth mentioning that the general approach employed in the Mt Cuba Echinacea trial is a very, very accessible one for the home gardener. Observe the plants in your gardens. See which ones bees and other pollinators are visiting. Observe plants in the wild. Go to nurseries and see which plants they’re offering that pollinators are visiting. In all those situations the plants that pollinators are visiting are the ones that are providing them with floral rewards. You’re not likely to be able to measure protein content of pollen are you? Believe me, you don’t need to.

Let me give you an example of how useful this approach is. In one of our gardens we have Great Coneflower (Rudbeckia maxima) planted right next to Northern Wild Senna (Senna hebecarpa). They bloom at different times so the comparison isn’t entirely fair, but Great Coneflower is quite unpopular with bees. Hardly a one comes visiting. In contrast, when Senna is blooming the plant is humming with activity. You’d be saying “Wow - look at all those bees!!!” Want to support pollinators in your garden? It’s a no-brainer - plant Senna not Great Coneflower.

So what’s going on with the Great Coneflower? I’m not entirely sure. It’s a straight species plant, not a cultivar. We are outside it’s native range here in New York (Arkansas - Oklahoma - Texas - Louisiana are where it hails from), so my best guess is that we simply don’t have the pollinator species living here that visit the plant in its native range). Or it could be largely self-fertile - it doesn’t need to be pollinated to produce seeds so it doesn’t expend energy to produce pollen and nectar that plants that want to be cross-pollinated need to invest in to attract pollinators. I don’t notice much seed set though on our Great Coneflower so my guess is that the former explanation is more likely. In contrast our garden lies within the native range of Senna - it’s not surprising we have a whole bunch of bees that will visit it when it’s in flower.

Want to take your observations to the next level? Sure get one of Heather Holm’s books. Both books are eye-opening to a world not easily seen and they’ll help you identify the different groups of bees in your garden and you can see, for example, if a particular plant is loved mostly by members of the Andrenidae family of bees and another one by members of the Halictidae family. Great fun.

Is that information necessary though for guidance in picking plants that support pollinators in your garden? Not really. Most bee species are what is called polylectic - they feed on a wide variety of plants. Some bees are oligolectic - they specialize on plants with particular floral structures, so they visit only a few plants out of those available to them at any given time. Then there are the very rare monolectic species - they have a very tight relationship with only a single genus of plants, perhaps even just a single species. Our Great Coneflower considered above may be an example of a species that mostly has specialist bees visiting it - and as I mentioned, perhaps those bees mostly are found within the range of the species, not outside it.

Observe. Then observe some more. It's the key to understanding the world around us!

Jacky Surber link

2/7/2021 10:39:57 am

Hi Benjamin,
Thank you for taking the time to think about and write such thoughtful and though provoking posts. I don’t find it easy to clear the mental space these days to have even similar conversations with myself though the thoughts arise. I look forward to the day when more people are educated on the basic terms you use so that we can all
have a larger conversation about this. The fact that the issue is so deep will take time for use to come to terms with the answer that seems obvious. We are all struggling to understand how we are a part of nature and what that means as we as humans are having are “tampering” with evolution in a more intentional and possibly destructive way than we have for thousands of years. Of course all that implies that we are also somewhat outside of nature and apart from it and that our selections are wrong in the eyes of the rest of life here on earth. A complex topic indeed.

Benjamin

2/7/2021 12:00:04 pm

Jacky -- It's good to hear from you. I hope you are well. It's not easy to write such posts these days, as you know. You are right -- it is such a deep, complex subject, and the more folks we have coming at it from various angles the better off we'll all be (it takes a village). I believe humans are absolutely a part of nature, but we have also set ourselves unnaturally outside of it given the rapid and total erasure of species and ecosystem function across the planet. We can either garden the planet as we have been doing, or alter our course with greater consideration and respect -- once we do the latter, we'll be even more a part of nature in empowering ways that generate equality across all species. But you knew I'd say all of this! :)

Derek Yarnell link

2/7/2021 10:34:31 pm

Thanks for the update on the trials and your perspective. I enjoyed the thread between you and Francis, and find value in both your perspectives.

I would love it if the resources were available today to test all the criteria you suggest in trials, and believe we should all keep advocating for them. Until then, as limited as it may be, it is exciting to at least begin to see some investment in understanding plant productivity. I agree there is more to measuring plant productivity than pollinator interactions and look forward to continued conversations on how to arrive at some consensus on how to define and measure it.

Benjamin

2/8/2021 09:15:14 am

Yes, there's so much more to explore, and we're getting there step by step. The Mt. Cuba study is one of the first steps and is therefore important as we go on our way. I still wish this conversation could also, equally, explore the ethical ramifications of plant modification for the aesthetic desires of one dominate species, but honestly, I did that in my book A New Garden Ethic in great detail. We can't forget that, in the end, this conversation is really about human dominance over ecosystems and finding ways to justify that dominance -- which is also why I feel it elicits such strong emotional responses (that's covered in chapter 3 of A New Garden Ethic, because the emotional feelings are a totally normal, acceptable, and important response).

Derek Yarnell link

2/8/2021 10:21:46 am

Benjamin, I am almost finished your book and am really enjoying it. We are spending a lot of time thinking about the same challenges and now that I have found your blog this will not be the last time you hear from me. I look forward to staying connected.

The Deep Middle