Benefit/Significance of Adding Subspecies

Those are the theoretical differences between variety and subspecies. On a practical level, we usually ignore those differences, treat varieties and subspecies as equivalent, but those are the distinctions we’d make if we thought about them.

The species concept given there is good, it’s what we’d like to see, but in fact some closely related species are more similar to that, which leads to a proliferation of definitions as we try to pin down this rather nebulous idea.


Juncus effusus (Soft Rush, though the leaf tips are stiff and painful, just not as stiff or painful as those of some other rushes) is an interesting case, I think.

First, the species level. Juncus effusus has recently been split in North America. Four or five native species have been split out of it in the Pacific Coast states. It’s also been split at the species level in the eastern states. However, the eastern vs. western botanists have been doing this work completely independently and it’s not clear how to reconcile these species from different sides of the continent, so the Flora of North America doesn’t recognize any of them. This is sad.

Juncus effusus itself has three major subspecies that I know about. Juncus effusus ssp. effusus is native to Europe. Juncus effusus ssp. solutus is native to eastern North America. Both of these have been introduced to the Pacific states & province, where J. effusus ssp. pacificus is native. Obviously, the differences matter.

These species and subspecies aren’t all that hard to tell apart if the appropriate parts are photographs. Unfortunately, the most important parts are the leaf sheath tops that are found near the base of the stems. Almost nobody photos these.


It isn’t always obvious to everyone that such differences matter. It could be a question of the degree of ecological equivalency.

I did make my statement from the position that native species belong here and introduced ones don’t, so we should know the difference and, where possible and practical, remove or at least don’t plant the introduced ones. At least, land managers should know what they’re managing, whether the species are native or not.

In the case of Juncus effusus, the three subspecies live in the same habitat or overlapping habitats. (I haven’t seen the introduced ones in wet pastured meadows where native J. effusus ssp. pacificus can thrive, but give them time.) At least one of the introduced ones is much taller than J. e. ssp. pacificus. Due to their ecological equivalence, the introduced ones may replace J. e. ssp. pacificus, at least in some wetlands.

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And I made mine from the position that they are all the same species. I question whether an invasive subspecies that is the same species as a native subspecies is equivalent to an invasive full species. At some point, we are approaching the level of metapopulations replacing other metapopulations, which has always been an ecological process.

Invasive subspecies rarely have an effect limited to their conspecifics.

From another thread, but it applies here:

The European subspecies behaves completely different than the American subspecies and replaces not only its conspecific, but creates huge monocultures replacing whole communities of native wetland plants in North America.

The thing to remember is there are many processes (e.g., extinction rates, climate change) that do occur naturally in moderation, but anthropogenic activities have sped these processes up beyond what is “natural” (outside of mass extinction events, which admittedly have also been “natural” historically).


Do american reeds not do that? Just curious.

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Correct, P. a. americanus does not usually form dense monocultures. Additionally, australis has tougher stems that take longer to degrade, so they often become denser stands with both new and old stems. Max height for americanus is like 7 feet and australis can be double that.

There is a second North American native subspecies P. a. berlandieri that I know very little about despite it being the more common of the native subspecies in my area (southeastern U.S.).


Very cool how it’s one species and behaves differently, we also have a second suspicies that is spreading, altissimus, not sure if it grows uniqely, but it’s 2 humans in height, much higher than regular australis.

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That depends. In the case of the Juncus, there are clearcut morphological differences between the subspecies. One might reasonably call them distinct species. I think those differences are worth noticing and including in management decisions. Some other subspecies blend together so much that I can’t really care.

Keep in mind that the decision to call two population different species rather than subspecies or even population within one taxon is to some extent arbitrary. I mean, the plants don’t care. Biodiversity conservation is about preserving the genetic variation, whatever we call it.


I love this, never heard it stated quite like that.

I get very worried with how much is being split these days that science will be used, once again, to support racism.

But brining it around to being about preserving diversity and not worrying so much about what exactly things are being called…happy sigh that just sounds so inclusive and friendly. This is so much better to focus on than categorical division. ^.^ I’d so much rather focus on species diversity than species division.


Ah! Now I see. If what I said were applied to humans, it could seem racist and anti-immigrant. I do not mean either of those. My concern is preserving biodiversity. I figure if each of us preserve the diversity around us, it will all be taken care of. So I want to preserve, for example, Juncus effusus ssp. pacificus from possible competition with other variations currently called subspecies of J. effusus.

Unfortunately, among humans, racism is its own force, independent of how biologists might want to name human groups. And if we consider human groups as different subspecies (which would be hard to justify, genetically, because the deepest divisions are within, not between, what we like to call certain races), we humans are undergoing “desubspeciation,” to parallel Dr. Barkworth’s term “despeciation” for the merging together of formerly distinct plant species. My own extended family is multiracial. (Besides the diversity in the current generations, my maternal grandmother is of Sami descent. Linnaeus lumped the Sami and two mytical human groups together in his species “Homo monstrosus.” So it goes.)

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I think Christensen’s list was prescriptive rather than descriptive—something he wished the community of plant taxonomists would agree with, not something the community of plant taxonomists did agree with. Different authors have proposed different criteria for when a taxon should be recognized as a form, variety, or subspecies, but I do not believe there is any general agreement, past or present.

If all three ranks are used, they are ordered from most to least inclusive as follows: subspecies, variety, form. That is the only distinction between them on which there is consensus. In practice, if only one rank is used I think people typically use a very pragmatic rule: try to keep all the infraspecific taxa in a genus (or tribe or family, as applicable) at the same rank because having a mixture of different ranks is annoying. For instance, in some work I was involved in, we moved a few names at varietal rank to subspecific rank because taxonomists working in Brassicaceae are mostly using the subspecific rank—no biological reason, just making the bookkeeping a little easier.


I think there is a consensus in the field of invasive species biology that invasive subspecies or varieties that belong to a species with native subspecies or varieties can be just as ecologically problematic as invasive species.


Humans are self-introduced outside of the region they evolved in, if we really cared much about own diversity, then big influx of out-of-Africa people can affect greatly our (as species) biodiversity, as genetically African continent is the most diverse one. Hopefully we don’t have another species looking after us, after all the problem of introduced species means so much only because most ecosystems are very much degraded, so people try to create a balance from whati is left. But we know many huge events when species got to a new place and replaced life that was there, before humans helped them. It is a normal process, but in normal situation any loss results in new biodiversity, now we can’t predict anything clear.

Every species, other than narrow endemics, is self-introduced outside the region it evolved in. I would go further and say that every species evolved originally as a narrow endemic.

I actually haven’t read most of the thread because I have Feelings™ haha. I did not mean to appear to accuse you of such, I simply wanted to comment about how much I loved the wording of what I quoted amongst a topic that can be…sometimes a scary road I feel like. :) My post was meant to be happy, becuase I do love how you described that bit I quoted and it gives me hope.

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Sorry. Actually, I wasn’t hurt by your post. (I have my own problems with understanding nuances of interactions among people – there are reasons I work with plants.) Because of your post I gained some insight into how mine could have been misinterpreted. That was good. I probably explained too much.

I did feel that what I’d written connected with you, communicated with you. That made me happy, and gave me something to remember when such an issue comes up again.


There was an old Charlie Brown cartoon
If I was a dog you would call me a mongrel.

Maternal - English, Irish, bit of French Hugenot, emigrant from Latvia, immigrants to Vancouver and California, Irish-Kenyan cousin.
Paternal - New Zealand, former East and West Germany, family originally Welsh, cousin with an Islander partner.
And my husband is Swiss.
But I was born in Cape Town. Living here among my fynbos with endemics, invasives, and …

Meanwhile - fascinating to follow taxonomists (relevant because it WAS a ssp). Having found African coromandel on Inat I was delighted to discover it in life at Kirstenbosch yesterday! (no camera)

PS someone who can needs to tackle the distribution map - many needing ‘planted in a garden so Not Wild’. I will sort them as I trip over them.

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