Question re source(s) for variety descriptions for Symphyotrichum lateriflorum

I wanted to ask a question to see if the Symphyotrichum people (or more) know a source or sources that I can use for the descriptions given for the varieties of S. lateriflorum. I have found taxons, distribution information, but no descriptions – what makes them different from the species. (I also found in FNA that the taxon has work to be done on it: “[m]uch genetic and phenotypic variation is encountered within the complex; a thorough study is needed before a coherent taxonomy can be achieved.” So I wonder if this means there really is no answer to my question.)

Here’s what I have so far and have added to the Wikipedia article in its own section, but when I do update it to include a better description of the species itself, I’d like to include what makes the varieties.


S. lateriflorum species is divided into the following infraspecies:[1][6]

  • S. lateriflorum var. angustifolium (Wiegand) G.L.Nesom – narrow-leaved calico aster, present in Ontario, Canada, as well as the U.S. region of New England except Rhode Island, and in the states of Indiana, Kentucky, Michigan, New Jersey, New York, and Wisconsin.[7] NatureServe lists it as possibly imperiled (S2) in Kentucky.[7]

  • S. lateriflorum var. flagellare (Shinners) G.L.Nesom – present in Oklahoma and Texas.[8]

  • S. lateriflorum var. horizontale (Desf.) G.L.Nesom – present in all U.S. states east of the Mississippi River excluding Indiana, Ohio, Virginia, South Carolina, and Louisiana.[9] Also present west of the Mississippi in Minnesota, Missouri, and Arkansas.[9] NatureServe lists it as imperiled (S2) in New Jersey.[9]

  • S. lateriflorum var. lateriflorum (L.) Á.Löve & D.Löve – calico aster.[10] Range is in the same provinces and states as the parent species as shown in the Distribution section of this article. NatureServe lists it as critically imperiled (S1) in Nebraska and Kansas.[10]

  • S. lateriflorum var. spatelliforme (E.S.Burgess) G.L.Nesom – present only in Florida.[11]

  • S. lateriflorum var. tenuipes (Wiegand) G.L.Nesom – slender-stalked calico aster.[12] Present in North America only in the Canadian provinces of Nova Scotia, Quebec, and Prince Edward Island, and in the U.S. states of Maine, Michigan, New Hampshire, New York, and Vermont.[13]

According to Flora of North America, “[m]uch genetic and phenotypic variation is encountered within the complex; a thorough study is needed before a coherent taxonomy can be achieved.”[3]

Additionally, there was a variety previously defined but now considered a non-accepted synonym of the species itself - S. lateriflorum var. hirsuticaule. I read somewhere not too long ago that it was a misidentification, I think by Lindley who originally defined it, and that it was S. lateriflorum with perhaps a few different but not distinct characteristics. I can’t for the life of me find where I read that, but I know it was online somewhere. It may have been in a scanned image of a book or on a website itself.

Finally, what would make a var. lateriflorum different from simply the species? Is that technically the variety for all the individuals that would not fall into the other varieties so that eventually, if the IDs on iNat could be sorted out into varieties, would all S. lateriflorum not in another variety go in that one?

I hope I explained myself at least semi-clearly. That was multiple questions. :roll_eyes:

Elizabeth Ballard


A brief excursion into plant taxonomy may be helpful here. To be validly published, the name of a new taxon must be accompanied by a description or diagnosis explaining what differentiates it from other taxa. The first description, and other accompanying data such as distribution, synonyms, etc., are called the “protologue” for that taxon. Sometimes, especially in older literature, the description may be less than informative, and a flora like FNA may be preferable in distinguishing the taxon from its relatives.

The name(s) of people following the scientific name of a taxon are the authorities–the people who described it. When you see one name in parentheses, followed by a second, the first authority initially described the taxon and wrote the diagnosis, and the second authority transferred their name to a different taxonomic rank, a different genus, etc. All of these varieties (except one, which we’ll come to) were transferred to Symphyotrichum by Guy Nesom; all were presumably originally described under Aster. To try to find some of these protologues, we can go to IPNI, although its coverage of sub-specific taxa isn’t always complete. If we search Aster lateriflorus we can find most of the original varieties, although some require more clicking through (e.g. S. lateriflorum var. spatelliforme started out as Aster spatelliformis E.S.Burgess). Most of these taxa have a link to “BHL”, the Biodiversity Heritage Library, which hosts a huge quantity of OCR’d scans of public-domain biodiversity and taxonomic literature. Clicking that will bring you to the original description for most, although var. flagellare was originally described in 1953 and that article does not appear to be in BHL.

The one exception here is S. lateriflorum var. lateriflorum. This is what’s called an “autonym”. Whenever anyone describes a new variety, subspecies, etc. of a particular species, their diagnosis has to differentiate it from the “normal” or “typical” material of that species; in particular, from the “type specimen”, a particular specimen (I’m glossing over a lot here) designated in the original species description. Individuals that resemble the original type specimen of the species rather than the specimen of the new variety would be assigned to the autonym at the varietal level. Nowadays autonyms are considered to be implicitly created whenever the diagnosis of the new sub-taxon is made; the authorities given there are really for the species, not the variety.

All this said, these varieties were all described by different individuals at different times. While Nesom presumably saw them as more or less compatible (he didn’t transfer every variety of Aster lateriflorus to Symphyotrichum), the Flora of North America caution is correct; without examining the range of variation in the species as a whole, it’s not clear that the current set of varieties is the most natural or correct way to divide up the species.


That’s a great response from @choess!
I’ll add that the autonym variety of a species doesn’t necessarily have to be most common or widespread variety (it really is more about which was described first and the arcane rules of botanical nomenclature). For example, I’ve done work on Lupinus lepidus, which has several varieties across the western US. The autonym variety, Lupinus lepidus var. lepidus, only occurs in Washington’s Puget Trough and Oregon’s Willamette Valley and is (in my opinion) imperiled. The much more common variety is L. lepidus var. lobbii, which is widespread at high elevations in the Cascades, Sierras, and other areas.
I’ll also say that, while the rules of nomenclature are quite ridged, the rules of taxonomy are nonexistent. In many ways each person is their own taxonomist. The names of all the Symphyotrichum lateriflorum varieties do exist, but it’s up to each person whether they recognize whether S. lateriflorum even has varieties. There is no official taxonomic decision maker that says yes or no to that question.
Okay, I’m being a little mischievous here. The above is true, but of course most people rely on some expert opinion. Taxonomic opinion also changes as more evidence emerges. Guy Nesom is an excellent taxonomist, but he’s definitely “a splitter” (probably accounting for why he chose to move all those varieties from Aster to Symphyotrichum, after Á. Löve & D. Löve already did the same for the species). Brouillet et al., who wrote the key for FNA, certainly saw all the same variation in the species that Nesom did, but chose to be more conservative, and not recognize those varieties. Their taxonomy only recognizes the species S. lateriflorum, and they need more evidence before they recognize all the varieties.
I guess that’s a very long way of saying that if you’re uncertain which variety an observation belongs to, don’t feel bad about just calling it S. lateriflorum without any variety.
I’m sorry I didn’t answer your actual question about how to tell the varieties apart. Since FNA doesn’t recognize them, you’ll probably have to cobble together floras from across the range of the species (if they recognize the varieties), or dive into the original literature (I often use Tropicos for finding where a name was first published).


@choess and @kweitemier, you have both “wowed” me. Thank you so much! This is very helpful. I’ve read each of your replies twice now and am so thankful that you have taken the time to respond thoughtfully and with such detail. I love iNat. I have learned so much in the past (has it only been?) 3 months since I joined.

What you have shared probably will cause me to pose additional questions. :)

I look forward to others’ replies, too.


Here are some thoughts, questions, ponderings…

Quoting @choess:

Incredibly! Thank you.

What does it mean when the first name in parentheses is followed by “ex” then another name still within the parentheses? For example, Symphyotrichum lateriflorum var. hirsuticaule (Lindley ex de Candolle) G. L. Nesom.

It has taken me until now to realize that I can use the data within Phytologia for this species from the BHL to then find the source for the original description. This will ease my frustration, assuming I can find those sources.

Perhaps I will luck upon it elsewhere.

This makes sense!

Which leads in to something I quote from @kweitemier.

Quoting @kweitemier:

With this in mind, it seems that I should be more conservative with the Wikipedia article and specify that Nesom recognized the varieties, but Brouillet, et. al., do not, and provide appropriate references. Good info.

Ahhhhh… it’s good to know which came first. Thank you. I mean, it would make sense that the move by Á. Löve & D. Löve came first, but your saying this makes it sink in.

Between what the two of you have said, I may be able to get what I need. And, in the end, I may find that I don’t need it at all.

Elizabeth Ballard


Interestingly, Haines’ Flora Novae Angliae does not recognize the varieties of Symphyotrichum lateriflorum, and instead only includes their names as synonyms. It does, however, list hybrids of S. lateriflorum with S. dumosum and S. puniceum. I’ve never knowingly seen an individual of this species I felt could fairly be considered a variety, as the natural variability I see seems to correspond mostly to site conditions, light availability, etc… I would certainly be curious to know other’s experiences with these varieties.

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The preposition “ex”, “out of”, is used in situations where one author invented a name but either did not publish it, or did not supply all the necessary elements for a valid publication. In botany, the author before “ex” is the one who coined the name, and the author after is the one who validly published it. (In zoological nomenclature, which is Like This, Only Different, the order is reversed, according to Wikipedia, which would seem to fit better with the preposition.)

In your example, the original name on which other combinations were based (the “basionym”) is Aster hirsuticaulis; its protologue was written by de Candolle, and in it he attributes the name to “Lindl. adn. mss.”, “Lindley’s manuscript notes”. So Lindley coined the name in an unpublished manuscript, but the first valid publication was by de Candolle.


I would as well! :)

Excellent info. Okay, so then G.L. Nesom moved var. hirsuticaulis to Symphyotrichum along with the other 5. At some point, someone decided that var. hirsuticaulis was a misidentification of the species itself (probably a very hairy specimen). I read this, recently, probably in September. I don’t know where. I can’t find it again. It’s interesting that we have a trail in the official name of who coined it, but not really one who got rid of it… other than to dig and hope for the best. Or do we?

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The species we now call Symphyotrichum lateriflorus (L.) Á. Löve & D. Löve was first officially described by Linnaeus as Solidago lateriflora L. on May 1, 1753.*

In 1836, Augustin de Candolle formally described the new species Aster hirsuticaulis Lindl. ex DC., based on John Lindley’s manuscript.

In 1889, Nathaniel Britton decided that Solidago lateriflora should really be a part of Aster, and so made the new combination Aster lateriflorus (L.) Britton.

In 1894, Thomas Porter determined that A. hirsuticaulis didn’t warrant being its own species, and was instead a variety of A. lateriflorus. He created the name Aster lateriflorus var. hirsuticaulis (Lindl. ex DC.) Porter.

It wasn’t until 1982 that Áskell and Doris Löve recognized A. lateriflorus as being a part of the genus Symphyotrichum, creating the name Symphyotrichum lateriflorum (L.) Á. Löve & D. Löve. Oddly, this was officially published as part of a long list of chromosome counts. I guess this implies to me that the Löves weren’t positively asserting that there were no varieties of S. lateriflorum, but rather they weren’t thinking about it (they were too busy counting chromosomes!).

Finally, in 1994 Guy Nesom did a big review of Aster sensu lato (that is, Aster in the broad sense, including all the genera that have been split off from it). There he wanted to still recognize these varieties of S. lateriflorum, and officially created new name combinations, including Symphyotrichum lateriflorum var. hirsuticaule (DC.) G.L. Nesom.

I don’t know who decided to stop using var. hirsuticaule, because to stop using a name is not an official nomenclatural act.** You simply just don’t use it (and presumably try to convince people that the idea that these things that have been called different names are really the same thing is a brilliant and well-researched opinion). The disused name still exists, so if someone later decides to recognize it, there’s nothing stopping them.

The botanical literature is basically drowning in names that officially exist, but aren’t recognized as being unique. Usually when someone publishes a monograph they will give the correct name*** of a species followed by a list of all the other names that technically exist but are synonyms.

*This date, and Linnaeus’ Species Plantarum, mark the official beginning of botanical nomenclature. Any plant names written before then don’t have official status. I’m uncertain whether Species Plantarum was actually published on this date, but it has been set as the cutoff.

**Well, there is actually a way to banish a name, usually if there’s a lot of confusion or conflicting names, but this requires a vote of the whole botanical taxonomic conference.

***Correct, here, is a technical term. However, whether a name is correct depends on the author’s idea of the underlying taxonomy. For example, it’s up to you whether you believe the type specimen of Aster hirsuticaulis is a different variety than the type specimen of Solidago lateriflora, but, if you do believe they are different varieties, and you believe they belong to the genus Symphyotrichum, then you must use the name Symphyotrichum lateriflorum var. hirsuticaule. Anything else is not correct.


@kweitemier I don’t know how I could ask for more than this, but after I digest it, you know that I will. Wow. :)


@kweitemier @choess and anybody else who would like to jump in…

It appears then, in November 2018, Michael Hassler classified all varieties as synonyms of the species itself ( This does not appear to be reflected in The PLANTS Database nor on NatureServe, which are the sources I was originally viewing. I still can’t find when or by whom var. hirsuticaule was “changed to” a synonym, but it appears to have been prior to Hassler doing that with the rest of the varieties of S. lateriflorum in 2018.

The ITIS, as well, does not reflect Hassler’s 2018 information (, nor does World Flora Online (

Does the Catalogue of Life’s data supercede these? Or is this one of the many things in life (or botany) that has the answer of, “It depends on who you ask”?


I think the best way to put it is that we’re now sliding over from nomenclature into taxonomy. If we think of classifying individual organisms as like putting items in a filing cabinet, nomenclature determines what labels we can put on each file, and taxonomy is about our decisions to put things in one file or another.

Nomenclature is (relatively) objective, in the sense that all botanists will usually agree on whether a given name has been validly published. However, the choice of what name to apply to which specimens is something else again. For any given name, a botanist might choose to accept that name, and the accompanying type specimen(s), and identify other individuals as belonging to that name rather than any other. Another botanist might consider that name and its type to be insufficiently different from some older name, and its type, to merit distinction and apply the second name instead.

The way in which a given botanist defines the boundaries of a taxon is called their “circumscription” of that taxon. These are, in my opinion, inherently fuzzy–no matter how clearly stated, there’s always the possibility of material turning up that will not lead to a clear result in a particular set of rules. In many cases, there’s a pretty strong consensus on what the boundaries of a taxon are, and there’s little or no difference between the circumscriptions used by different authorities. On the other hand, some circumscriptions have shifted quite a bit over time, and may vary quite dramatically depending on whether the botanist is a “lumper” or “splitter”. (Hence the terms “sensu stricto”, “s.s.”, and “sensu lato”, “s.l.”; they mean “in the strict sense”, that is, having a fairly narrow circumscription, and “in the broad sense”. You often see them used when some authorities have “lumped” several taxa under one name and others have split them.)

You’re working with sub-specific taxa, which is particularly fraught. Oftentimes, the compilers of large lists and catalogs of species, like the ones you’ve named, choose not to recognize most or all subspecies, varieties, etc. That isn’t necessarily a final judgment against the existence of distinct sub-specific units so much as a concession to their lack of time and material to critically scrutinize material within that species. In other words, sometimes people lump because they don’t have the data to confidently split.


Could DNA testing solve all these once and for all? :)

I’m not a taxonomist, but my impression is that while DNA testing answers some questions, it ends up producing many, many more puzzles!


Another example: ever wonder why such a tall, straight tree as lodgepole pine is called Pinus contorta? It is because the first specimens described scientifically were the dwarfed coastal dune population, which are indeed contorted (by seashore conditions).


No. If you accept the criterion of monophyly (that any given taxon should contain all the descendants of a common ancestor, a clade), DNA reconstruction of phylogeny can make you pretty confident that certain individuals shouldn’t be lumped together. However, clades in a phylogenetic tree can nest to an arbitrary depth. Both lumping together a pair of sister clades as one taxon and treating them as two separate taxa produce a monophyletic classification; which approach to adopt is a matter of taxonomic judgment. There’s no quantitative measurement obtained by DNA sequencing that defines a boundary between “conspecific” and “not conspecific”. (At least not for eukaryotes; with microbes things are somewhat different, see for some background.)


OP here. I just want to thank everyone again for your input. I am not finished “digesting” the info and will most likely still have more questions. I am learning to love this community. There is so much knowledge and generousity in sharing here. :)


Does anyone know if Flora of the Chicago Region (2017) recognizes the S. lateriflorum varieties?

It doesn’t, but says:

There appears to be two elements of this species in our flora. The one that is conservative to fens is yellowish-green with coriaceous leaves, and the element occurring in other habitats is darker green with more membranaceous leaves.