White-flowered red trillium (update)

Trillium erectum L. is a species of flowering plant widely distributed across eastern North America. It is commonly called the red trillium based on the typical color of its petals but other petal colors are possible. In particular, two distinct taxa of white-flowered red trillium have long been known. The name Trillium erectum var. album (Michx.) Pursh has been variously applied to one or both of these taxa.

As of April 2022, Plants of the World Online (POWO) restricts the range of Trillium erectum var. album (Michx.) Pursh to eastern Tennessee and western North Carolina, citing the Flora of the Southeastern United States as an authority. The occasional white-flowered red trillium found throughout the range of the species is no longer included in POWO’s concept of the taxon. The following article explains this taxon in more detail:

Publicado el 11 de abril de 2022 a las 11:52 AM por trscavo trscavo


Thank you for clearing up this confusing taxonomy!

Anotado por tsn hace cerca de 2 años

The analysis in Flora Novae Angliae (quoted in the google doc) is spot on, and the editors at POWO agreed :-)

Anotado por trscavo hace cerca de 2 años

WOW! Very cool update!

Anotado por flowntheloop hace cerca de 2 años

So much to learn, and so little time!!

Anotado por linkmdavis hace cerca de 2 años

@trscavo - What are your thoughts about the high-elevation predominantly white- and narrow-petaled T. erectum plants in the southern Appalachians?

e.g.: https://www.inaturalist.org/observations/12669120, https://www.inaturalist.org/observations/82590100

I noticed that FSUS singles out low-elevation plants in particular for T. erectum var. album.

Anotado por ddennism hace cerca de 2 años

In Flora of North America (FNA), Frederick Case claims the white form is dominant at altitudes lower than 450 meters (1475 ft). Perhaps FSUS is getting that from FNA, I don't know, but to answer your question, yes, those observations seem to be var. album, especially if they come from local populations where the white form is dominant. The occasional white form (presumably a result of simple mutation) can occur in any population, even in the Great Smoky Mountains.

Anotado por trscavo hace cerca de 2 años

So, just to be clear, you're ultimately citing FSUS, but then disagreeing with its elevation claim?

Anotado por ddennism hace cerca de 2 años

No, I don't think I'm disagreeing with FSUS at all: "..usually at low elevations. Distribution poorly understood.."

Anotado por trscavo hace cerca de 2 años

For those interesting high elevation plants, I guess we'll have to agree to disagree in the face of incomplete (or unfinished in the case of POWO?) information.

Elevation is the only feature offered to distinguish white-petaled T. erectum var. erectum from T. erectum var. album in FSUS, so it seems pretty important to me.

Considering that FSUS itself maps var. album to regions far from the southern Appalachians, it seems like the sources you cite so authoritatively are actually in quite a bit of internal disagreement with respect to this taxon.

My advice is to move all infraspecific identifications in T. erectum to the species-level until someone does the hard work of sorting this out in a peer reviewed publication.

Anotado por ddennism hace cerca de 2 años

Thanks @ddennism for your advice. You seem to be focused on T. erectum in the southern Appalachians but that's not what this about. It's about not using T. erectum var. album outside of the southern Appalachians. Identifiers are now able to disagree with var. album outside of the southern Appalachians while citing POWO in the process. IMO that's a much better situation than before.

Anotado por trscavo hace cerca de 2 años

Only a few (obviously) mis-identified observations remain. Thanks everyone for your help!

Anotado por trscavo hace cerca de 2 años

Definitely agree with respect to using "var. album" for northern plants, and kudos, by the way, for putting all this together.

But those southern Appalachian populations are actually salient here, because they demonstrate the inappropriateness of using infraspecies taxa in T. erectum, at least as currently described in the sources you give.

Anotado por ddennism hace cerca de 2 años

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