Heads up: Some or all of the identifications affected by this split may have been replaced with identifications of Viburnum. This happens when we can't automatically assign an identification to one of the output taxa. Review identifications of Viburnum nudum 153200

Taxonomic Split 113929 (Committed on 08-29-2022)

Discuss at https://www.inaturalist.org/flags/585997

Viburnum nudum and V. cassinoides are accepted as separate species in Plants of the World Online, as well a most of the relatively up-to-date regional sources such as VASCAN, Flora of the Chicago Region 2017, and Weakley 2022. V. nitidum has been an available separate taxon on iNat since April 2019.


In Spriggs et al. 2019 (https://academic.oup.com/sysbio/article/68/2/187/5232147),

The view is widespread that plant species are often difficult to delimit due to hybridization, polyploidy, asexual reproduction, and phenotypic plasticity (e.g., Levin 1979). At the outset, the V. nudum complex appeared to be a classic case of such difficulties. However, it turned out to be surprisingly straightforward, and this offers hope that the confluence of molecular, morphological, geographical, and ecological data, along the lines demonstrated here, will prove to be the rule in plants rather than the exception.

Our molecular analyses have clearly identified three distinct lineages, one of which (V. nudum) is highly divergent from the other two. The morphological differences among the three clades are minor, but V. nudum can be distinguished with considerable confidence based on morphology alone. The more recently diverged V. nitidum and V. cassinoides are not so clearly separated based on morphological traits, but molecular evidence indicates that these two clades are isolated by more than geographic distance, and they appear to have maintained their separation through significant geographic movements during glacial cycles. Based on all of the available evidence we hypothesize that these three lineages are evolving independently, and we therefore, recognize them as separate species.


[V. cassinoides] often has wide, ovate leaves with crenate margins and displays of pink (immature) and black (mature) fruits. In the South, V. nudum and V. nitidum are broadly sympatric, and can co-occur in close proximity. Viburnum nudum leaves tend to be larger (20–30 cm2)⁠, thicker, rounder, and more acute or obtuse (as opposed to acuminate) than they are in V. nitidum (blade size 10–18 cm2)⁠. In addition, V. nudum often has in-rolled leaf margins and its leaves frequently dry darker on herbarium specimens. The main stalk of the flat-topped umbel-like inflorescence tends to be longer in V. nudum (33–44 mm) than it is in V. nitidum (16–29 mm). Finally, in late July and August, V. nudum fruits are often pale green to white, whereas the fruits are pink or black in sympatric V. nitidum populations. Viburnum nudum fruits ultimately mature to a dark blue or black color, but we have never observed the prolonged phase of bright pink that is, typical in both V. nitidum and V. cassinoides.

In August 2022, the subspecies of V. nudum were elevated to species on iNaturalist:

This species split completes the taxon changes required to update this taxonomy, narrowing the concept of V. nudum on iNaturalist from sensu lato (southern and northern) to sensu stricto (principally southern).

In areas where the atlases do not overlap, V. nudum IDs will be auto-reassigned to either V. nudum or V. cassinoides. In areas where the atlases overlap, the V. nudum IDs will be bumped to their common ancestor, genus Viburnum.

POWO (Citation)
Added by bouteloua on August 28, 2022 02:38 PM | Committed by bouteloua on August 29, 2022
split into


Posted by bouteloua almost 2 years ago

I spent a considerable amount of time going through and identifying these, and I was almost done going through all of them and now all of my identifications have been changed. Is there any way to revert to all of my previous IDs? There are many observations that were actually V. nudum (common landscaping plant) that have been changed to V. cassinoides, and many of the V. nudum from the east coast of North Carolina up through to around NYC which have been incorrectly changed to V. cassinoides.

Posted by bpagnier almost 2 years ago

Hm, this is very strange. When I created the atlas for V. nudum, it followed the sources I listed on the atlas, which went significantly further up the east coast up to NY, CT, and RH. However, several states were removed from the atlas and do not have a username listed as affiliated with their removal. I didnt make any changes to the atlases today before pressing commit (8/29).

I checked the atlases multiple times including immediately before committing the change.

I wonder if this could at all be related to iNat rebuilding after the downtime, and I am thinking that this taxon change may need to be reverted to fix all the incorrect V. cassinoides IDs and so that this can be investigated. @kueda @loarie

Posted by bouteloua almost 2 years ago

do you have an example of an observation that was ID'd at Viburnum nudum that had a different outcome than you were expecting? If so I can investigate

Posted by loarie almost 2 years ago

It's just frustrating because I thought the taxon swap was completed two weeks ago so I had spent that amount of time correcting observations, and now a lot of correctly ID'd observations at V. nudum var. nudum from northern states are now V. cassinoides

a couple examples:

The same has happened with observations along the east coast where the natural range extends:

a lot of the states I had already corrected, but suddenly all of the V. nudum are pushed back to genus.

As frustrating as it all is it seems people have already began correcting their observations again so it would probably be best just to leave it be. Just seems to be quite a step back from where we were at.

Posted by bpagnier almost 2 years ago

(deleted comment - I was out in the field and haven't fully investigated - in progress)

Posted by bouteloua almost 2 years ago

Ok - sorry for the false alarm Scott (was squinting at my phone in the sun tryna figure out what went wrong before people spent a bunch of effort trying to manually fix things).

The atlas for V. nudum is indeed completely changed from how I had set it up as (why?), but when I went through IDs in places where the atlases previously overlapped but currently do not, I'm not seeing anything unexpected. The V. nudum IDs were bumped to genus as expected. At least, so far from looking through. For example. WV was one of many states somehow removed from the V. nudum atlas, but the IDs there were bumped to genus as planned: https://www.inaturalist.org/observations/83545799

And Blake's examples are outside of the V. nudum sensu stricto range documented in the NY Flora Atlas, which is what I used for the atlasing here on iNat.

Taxon splits / atlasing never performs well for plants that are in cultivation outside of their natural range, and I'm not sure how much discussion has happened around potential resolutions to that. (should atlases represent captive/cultivated "ranges" too? how would curators know, what sources would be used? should taxon splits exclude captive/cultivated observations? etc)

Posted by bouteloua almost 2 years ago

@bpagnier - I'm really sorry that a lot of your identifying efforts have to be redone. Part of why it's really important to do a set of related taxon changes at the same time rather than piecemeal.

Posted by bouteloua almost 2 years ago

re: why the atlases changed: I haven't looked into this carefully, but I think I've also seen what you're referring to which is that the split moves listed taxa around which changes the atlases. Currently listed taxa are quite complex particularly in how they interact with observations, so I wouldn't be surprised if the way a split changes IDs changes obs in a way that changes listed taxa. I also agree that that shouldn't happen though. I made an issue to look into this deeper https://github.com/inaturalist/inaturalist/issues/3505 if anyone could provide (a) a screen shot of an atlas presplit, (b) a split, and (c) a screen shot of an atlas altered by the split post split, that would be hugely helpful in reproducing this

Posted by loarie almost 2 years ago

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