Phytoneuron

Nesom, G.L 2010. Sectional name for the group including Ehgeron radicatus (Asteraceae: Astereae). Phytoneuron 2010-18:
1-2. Mailed 13 May 2010.

SECTIONAL NAME FOR THE GROUP INCLUDING ERIGERON RADICATUS
(ASTERACEAE: ASTEREAE)

GuyL. Nesom
2925 Hartwood Drive
Fort Worth, TX 76109
www.guynesom.com

ABSTRACT

Erigeron sect. Radicati (Rydb.) Nesom (of 2008) was without a clear taxonomic position as
published— it is ketotypified here by E. nematophyllus and becomes a synonym of Erigeron sect.
Wyomingia (of 1947). Engeros* sect. Radicatiformes Nesom, sect. nov. (type: E. radicatus) is
described here to include the five species placed in error within sect. Radicati in 2008.

In a classification of the Conyzinae (Nesom 2008), the combination Erigeron sect. Radicati
(Rydb.) Nesom was formalized, based on Erigeron [unranked] Radicati Rydberg (1906), as the name
for a group including E. radicatus Hook, as well as E. lackschewitzii, E. ochroleucus, E. parryi, and
E. rydbergii. Erigeron radicatus, however, does not occur in Colorado, and it was not among the five
species of Rydberg's Radicati group in his Flora of Colorado (1906), although Rydberg later (1917)
included E. radicatus in that group and probably had earlier intended to imply its membership there.

In any case, Rydberg's "Radicati group" of 1906 cannot stand as the basionym of a name for
the 2008 group, because none of the species in the 1906 group were in the 2008 group — all were in
different sections.

Rydberg's Radicati:

Erigeron engelmannih E. vetensis (syns = E. gianduiosus, E. viscidus) — in sect. Stenactis, 2008

Erigeron leiomerus — in sect. Scopulincola, 2008

Erigeron nematophyllus — in sect. Wyomingia, 2008

Erigeron peasei (= E. flagellaris) — in sect. Olygotrichium, 2008

Erigeron ursinus — sect. Rhizonexus, 2008

Thus, because of the superfluous and rejected type citation, Erigeron sect. Radicati is valid and
legitimate but, without a lectotype species, it lacks a cleai taxonomic position.

The situation is clarified and rectified here by described a new section, correctly typified, for
the group of 2008 and by providing a lectotype for Erigeron sect. Radicati

Erigeron sect. Radicatiformes Nesom, sect. nov. TYPE: Erigeron radicatus Hook.

Caudice multicipitaii, radice palari, cauiibus simplicibus capitulis l(-3), foliis oblanceolatis
vel spatulatis abaxialiter glabris vel glabratis, et acheniis 1.8-2.8 mm in longitudine distinctus.

Species included: E. lackschewitzii Nesom &. Weber, E. ochroleucus Nutt, E. parryi Canby
& Rose, E. radicatus Hook., audi?, rydbergii Cronq.

Erigeron sect. Radicati (Rydb.) Nesom, Lundellia 11: 26. 2008. Erigeron [unranked] Radicati
Rydb., Fl. Colorado 359. 1906, in clave. Lectotype (designated here): Erigeron
nematophyllus Rydb, With this lectotypification Erigeron sect. Radicati becomes a synonym
of Erigeron sect. Wyomingia (A. Nels.) Cronq., as delimited in Nesom (2008).

ACKNOWLEDGEMENTS

I'm grateful to Kanchi Gandhi for pointing out the problem in typification with my original
elevation in rank of Rydberg's Radicati group.

LITERATURE CITED

Nesom, G.L. 2008. Classification of subtribe Conyzinae (Asteraceae: Astereae). Lundellia 11: 8-38.
Rydberg, P. A 1906. Flora of Colorado. Colorado State Agric. Expt. Station Bull. 100: 1-448.
Rydberg, P. A 1917. Flora of the Rocky Mountains and Adjacent Plains. Steinman & Foltz.
Lancaster, Pennsylvania.