Journal archives for September 2022

September 01, 2022

Discoid Grindelia squarrosa back to Grindelia nuda again

Grindelia nuda is a rayless (eradiate/discoid) species of Grindelia with blunt or rounded leaf teeth terminated with glands, defined initially by Wood(1878) based on a collection in what is now Oklahoma. For much of its history, it has been treated as a variety of Grindelia squarrosa (Gray 1884; Steyermark 1934; Correll and Johnston 1970) and briefly again as G. nuda (Nesom 1990; Diggs et al 1999) until is was synonomized with Grindelia squarrosa in the Flora of North America by Strother and Wetter(2006). Plants of the World Online (POWO), which iNaturalist uses as its main resource for botanical names, followed this synonomy until some unspecified time in the last couple of years (perhaps following a change in the September 2021 release of the World Checklist of Vascular Plants) when it accepted Grindelia nuda as a valid species again, referencing Powell and Worthington's Flowering Plants of Trans-Pecos Texas and Adjacent Areas. There has been a fair amount of resistance to some of the taxonomy of Strother and Wetter in at least one comprehensive treatment (Bartoli and Tortosa 2012) and a number of regional floras (Moore 2012; Ackerfield 2015; Powell and Worthington 2018), but that is a broader discussion.

On iNaturalist, G. nuda was never synonomized with G. squarrosa due to flagging in 2016 to maintain it as an accepted name. Despite that, following the FNA and POWO, I (and maybe others) identified most G. nuda specimens up to this point as G. squarrosa. As a result, there are at least several hundred specimens (based on research grade specimens of G. squarrosa in Texas) that will need to be reidentified as G. nuda at some point. In Texas, this should be fairly straightforward since G. nuda is the only rayless (eradiate/discoid) species in the state except for the rare G. oolepis in South Texas. However, it will be a manual process as there are a few actual G. squarrosa in northeast Texas. POWO, following Powell and Worthington (which follows Nesom 1990), recognizes two varieties of G. nuda, var. nuda and var. aphanactis. These appear to be distinguished mostly by leaf morphology (specifically the length to width ratio), and might be difficult to differentiate in the field. However, Nesom indicated that var. nuda occurs mostly to the east in Texas, Oklahoma, Kansas and southeast Colorado while var. aphanactis occurs to the west mostly in New Mexico, southern Colorado, and Arizona. He also recognized a zone of intermediacy in areas of west Texas. It is also worth noting that genetic evidence in Moore et al(2012) indicates that the two may be separate species, despite their great morphological similarity, so it is plausible that the two varieties may be separated in the future.

Heads from above (Burnet, Williamson, and Kimble counties in Texas)

Head profile

Leaves, typically cauline mid-stem

Observations used in this post

Burnet county : 62455288
Williamson county: 8003651
Kimble county: 97271324


Ackerfield, J. 2015. Flora of Colorado. BRIT Press.
Bartoli, A. and R.D. Tortosa. 2012. Revision of the North American species of Grindelia (Asteraceae). Ann. Missouri Bot. Gard. 98: 447–513.
Correll, D.S. & M.C. Johnston. 1970. Manual of the Vascular Plants of Texas. Texas Research Foundation, Renner, Texas.
Diggs, G. M., Lipscomb, B. L., O'Kennon, B., Mahler, W. F., & Shinners, L. H. 1999. Shinners & Mahler's Illustrated Flora of North Central Texas. Botanical Research Institute of Texas.
Gray, A. 1884. Synoptical Flora of North America 1(2): 118.
Moore, A.J. 2012, Grindelia, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on August 30, 2022.
Moore, A.J., Bartoli, A., Tortosa, R. D., & B.G. Baldwin. 2012. Phylogeny, biography, and chromosome evolution of the amphitropical genus Grindelia (Asteraceae) inferred from nuclear ribosomal and chloroplast sequence data. Taxon 61(1): 211-230.
Nesom, G. L. 1990. Studies in the systematics of Mexican and Texan Grindelia (Asteraceae: Astereae). Phytologia 68: 303–332.
POWO. 2022. Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; Accessed 30 August 2022.
Powell, A.M. & Worthington, R.D. 2018. Flowering plants of Trans-Pecos Texas and adjacent areas: 1-1444. BRIT Press.
Steyermark, J. A. 1934. Studies in Grindelia. II. A monograph of the North American species of the genus Grindelia. Ann. Missouri Bot. Gard. 21: 433–608.
Strother, J. L. and M. Wetter. Grindelia. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 20+ vols. New York and Oxford. Vol. 20.
Wood, A. 1878. Grindelia nuda. Botanical Gazette 3(6): 50. 1878.


All photos used in this post are the property of Ryan McDaniel, all rights reserved.


0.1 - September 1, 2022 - Initial.
Posted on September 01, 2022 05:52 PM by rymcdaniel rymcdaniel | 18 comments | Leave a comment

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