September 21, 2020

Plant genus Lasiopogon Cass. (Asteraceae: Gnaphalieae) new to North America

This is one of the many reasons I love iNaturalist.

About 4 years ago I started noticing some unusual "Gnaphalium palustre" observations from southern Arizona (plus one so far from southern California). I gave them that identification as a "best fit," but with reservations often expressed in the comments.

Seeing another one yesterday was my last straw, and I decided to pull out all stops to see if a better name could be found for these plants. It was increasingly apparent that these plants are not Gnaphalium palustre, nor anything else known in the Arizona or California floras.

So what was my first go-to for doing further research? Why, iNaturalist of course! Using the Compare feature on the most recent observation, I first looked through all the Asteraceae tribe Gnaphalieae observed or listed for North America, doing Google image searches for taxa that didn't have photos in iNaturalist. (And of course, also taking the iNaturalist photos with the appropriate grain of salt too.) Nothing else in North America was close to a match.

Next, knowing where Gnaphalieae tend to be more diverse, I did the same search in Australia. Still nothing. Next was Africa. Bingo! Some iNaturalist photos associated with Lasiopogon observations from southern Africa showed exactly the same distinctive head apices I had been noticing in the North American observations, and the rest of the plants were matching also.

The relevant North American observations are now here -- if the page comes up blank, wait a few moments for it to populate. It's using a special URL that slows it down. (Caution all, when adding identifications, it's easy to accidentally add the fly genus Lasiopogon instead of the plant genus!)

@ngb
@tonyrebelo
@botaneek
@fragmansapir
@kai_schablewski

can you have a look through the observations linked in the paragraph above, and see if it's possible to identify the species for any of them? Based on existing geographic range, the most likely candidate for introduction to North America would be Lasiopogon muscoides. The RG Lasiopogon observations on iNaturalist, however, seem to show two different things under this name, one with shorter, fuzzier, and denser leaves than the other (the other looking more like the North American plants). And there is also a Lasiopogon brachypterus observation looking pretty similar to the North American plants.

At least judging from the records on SEINet and the California Consortium, no North American specimens have yet been identified as Lasiopogon. [UPDATE 2020-10-15: two specimens have now been uncovered at ASU.] Considering that, plus the fact that iNaturalist observations didn't start showing up until about 4 years ago, and that they are concentrated in disturbed habitats around the Phoenix and Tucson metro areas, suggests that this might be a fairly recent introduction (and possibly the first in the Western Hemisphere). If so, it has already spread pretty rapidly. But there could also be older records that have been fooling North American plant taxonomists until now.

In any case, there are likely Lasiopogon specimens in Arizona and other herbaria at this point that are misidentified as Gnaphalium or other Gnaphalieae. And there are likely more iNat observations of it waiting to be surfaced, most likely here, and possibly a few here and here. Heads up @aspidoscelis @dhwilken @gentilcore @jrebman @rojosmojo @sabra2 @stevejones -- and please @ tag (in a comment below) any other inatters who work with regional herbaria, or could help identify Lasiopogon to species level.

Posted on September 21, 2020 00:16 by jdmore jdmore | 18 comments | Leave a comment

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