Content Author Object Flagger Flag Created Reason Resolved by Resolution
Hairy Beggarticks (Bidens pilosa) durling Tue, 07 May 2019 18:47:55 +0000

Distinction between B. piles and B. alba. See comments.


committed taxon change


It appears that there is some confusion between B. pilosa and B. alba. Images and ranges for these species according to POWO and Atlas of Florida Plants indicate that many of the species identified as B. pilosa should be identified as B. alba.

B. pilosa

B. alba

Posted by durling about 3 years ago (Flag)
Posted by durling about 3 years ago (Flag)

The rival taxonomies are certainly frustrating. I have chosen to ID based on iNat’s preference as noted above until consensus is reached or iNat changes its preference.

Posted by ryancooke about 3 years ago (Flag)

According to the above posting, iNat previously used The Plant List as the tie breaker for resolving rival taxonomies on the site. However, as of last August they made a change to using Plants of the World online as the default.

The merger of B. alba into B. pilosa appears to have been made based on the previous default to The Plant List. It would then seem that a change should be made to split based on the new default authority.

Posted by ryancooke about 3 years ago (Flag)

@loarie With over 6600 observations impacted, this seems like a good candidate for you to weigh in on.

Posted by ryancooke about 3 years ago (Flag)

ryan that post is a bit old - iNat now uses the TaxonFramework system
for describing external sources and managing deviations
For vascular plants, POWO is the external source:
but disruptive changes should be discussed first and we can always deviate from POWO.

Posted by loarie about 3 years ago (Flag)

Nevertheless, there appears to be a problem with Bidens pilosa. It appears that POWO and the Plant List do not agree on its taxonomy. Images and ranges for these species in POWO indicate that many of the species identified as Bidens pilosa should be identified as Bidens alba. Also, note that Bidens pilosa var. alba ( does not appear in POWO and the Plant List. Bidens pilosa var. albus is listed as synonymous with Bidens alba.

As @ryancooke pointed out, it appears that Bidens alba was lumped into B. pilosa back in 2017 based on The Plant List. @japlaca

The question here is, what authority do we want to align with?

Posted by durling almost 3 years ago (Flag)

Clinging in.
In Mexico, CONABIO chooses to maintain the Bidens pilosa complex as separate species:
B. alba: Up to 8 ligules that are notably longer than wide. Relatively short external (green) bracts. See
B. pilosa: Absent or reduced ligules. At least some fruits with three awns instead of two. See
B. odorata: 5 ligules that are barely longer than wide. Longer external bracts. See
See also:

Posted by bodofzt over 2 years ago (Flag)

At present one cannot identify a plant in iNaturalist as Bidens alba, iNaturalist will automatically submerge a Bidens alba identification in Bidens pilosa. PoWO has these as distinct species. PoWO is the authority, these should be split, although how to handle the split escapes me as the introduced ranges include the other species.
If nothing else, Bidens alba should be resurrected so that plants can be identified to Bidens alba. For now perhaps the only option is to ID to Bidens pilosa ssp. alba.

Posted by danaleeling over 2 years ago (Flag)

Hi there,
I recently made some new observations of this Spanish needle species in Broward County, Florida, USA.
Noting the problems with the species classification, I've for now just listed them under the "Bidens" genus.
Has there been any update on this issue?

Posted by glennmagusharvey about 2 years ago (Flag)

Bidens alba has now been added to POWO, so I've added it to our collection.

Posted by kitty12 almost 2 years ago (Flag)

Soooo... Gotta change all false Bidens pilosa swaps back to Bidens alba. :-/

Posted by bodofzt almost 2 years ago (Flag)

@kitty12 before Bidens alba is activated, a taxon split should be drafted for Bidens pilosa split into a new Bidens pilosa taxon + Bidens alba (and any other species formerly considered part of it on iNat).

Posted by bouteloua almost 2 years ago (Flag)

Yikes - it looks like a lot of stuff has already been added.

Posted by kitty12 almost 2 years ago (Flag)

Sorry if that was done too precipitously.

Posted by kitty12 almost 2 years ago (Flag)

With over 12,000 observations this is going to be one of those disruptive changes @loarie mentioned above. Are they all going to be dumped back into Bidens for people to sort from there?

Posted by ryancooke almost 2 years ago (Flag)

if B. pilosa (sensu lato) is split and there's no way to separate observations of B. pelosa (sensu tricot) and B. alba by range (ie atlases), then yes they will all get rolled back to Bidens and have to be manually re ID'd to species.

Posted by loarie almost 2 years ago (Flag)

Range is overlapping, so we'll have to organize an ID-swapping marathon or something.

Posted by bodofzt almost 2 years ago (Flag)

yep, after the split

Posted by bouteloua almost 2 years ago (Flag)

okey dokey, guess I'll do it.

@loarie, when you get a chance can you take a look at this and hit commit when it makes sense to as far as affecting the iNat infrastructure?

(see other flag I just made for B. odorata:

Posted by bouteloua over 1 year ago (Flag)

Sounds great. I'll definitely help with the ID-swapping marathon when/if needed.

Posted by durling over 1 year ago (Flag)

I suspect I can only help for those few observations on Pohnpei where we have herbarium sheets to back up our identifications.

Posted by danaleeling over 1 year ago (Flag)

Hello everybody. Have it an overlap of this two species in South America?

Posted by regisrafael over 1 year ago (Flag)

Here in SE Asai Bidens sp is a common and major invasive species. My understanding is that the majority of it here is B. pilosa not B. alba, but if anyone has better info it would be appreciated.

Posted by earthknight over 1 year ago (Flag)

According to the Atlas of Florida Plants, B. pilosa does occur as an introduced species here in Florida, USA: Yet, every B. pilosa observation in FL was changed to B. alba. I fully support the move to change Florida observations of B. pilosa to B. alba, but I question whether B. pilosa has truly not made it to FL. I would greatly appreciate any input on this!

Posted by aliandbrice over 1 year ago (Flag)

@jayhorn - Can you confirm or deny that B. pilosa is present in FL?

Posted by aliandbrice over 1 year ago (Flag)

re Asia, from the Nov 2020 Kong Kong bioblitz, I got the impression that much of the Bidens being id'd as pilosa there were maybe alba instead; herbarium ref appears consistent with that?

Posted by lotteryd about 1 year ago (Flag)

Yes, much of the Asia B. pilosa was actualy B. alba.

Posted by aliandbrice about 1 year ago (Flag)

Weren't both B. pilosa and alba already existing as separate taxa on iNat? I'm not sure why this taxon adjustment was needed if so.

Posted by silversea_starsong 8 months ago (Flag)

@lotteryd - according to that link both B. pilosa and B. alba are widely naturalized in the region.

B. pilosa: Locality: Naturalized and widely distributed in Hong Kong. H. C. Tang 2357; Y. S. Lau 85; S. Y. Hu 5293 (CUHK).
Distribution: S to C, E to SW China; widely distributed in Asia and tropical America.

B. alba: Locality: Naturalized and widely distributed in Hong Kong. Y. S. Lau 3191; Y. W. Lam 21.; S. Y. Hu & Y. C. Kong 050 (CUHK).
Distribution: Native to tropical America, widely naturalized in the tropics.

The CABI database indicates that B. pilosa has a wider distribution.

B. alba:

B. pilosa:

Posted by earthknight 8 months ago (Flag)

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