1. Amphiachyris dracunculoides (DC.) Nutt. (syn.: Brachyris dracunculoides DC., Gutierrezia dracunculoides (DC.) S.F. Blake, Xanthocephalum amoenum Shinners var. intermedium Shinners) (N-Am.) – An exceptional and ephemeral alien. Recorded once but in abundance (several 100’s) on gravelly soil near a porcelain factory in Vorst (Laakdal) in 1990.
This record was originally ascribed to Schkuhria abrotanoides (D’hose & De Langhe 1991). Indeed, the general appearance of Amphiachyris dracunculoides is somewhat similar to that of species of Schkuhria (erect, distally branched annuals with numerous inconspicuous capitulae) but they are not even remotely related. Amphiachyris belongs to the tribe Astereae while Schkuhria pertains to tribe Heliantheae. Amphiachyris has a strong terpenoid smell and the involucre is glandular-resinous.
The mode of introduction of Amphiachyris dracunculoides in Vorst remains obscure. It was recently also recorded in a gravel pit in northeastern France (ephemeral).
Selected literature: D’hose & De Langhe (1991; sub Schkuhria abrotanoides).
Literature
D’hose R. & De Langhe J.-E. (1991) Nieuwe groeiplaatsen van zeldzame planten in België. XIX. Belg. J. Bot. 124(2): 115-118.
Lane M.A. (1979) Taxonomy of the genus Amphiachyris (Asteraceae: Astereae). Syst. Bot. 4: 178-189.
Nesom G.L. (2006) Amphiachyris. In: Flora of North America Editorial Committee (eds.), Flora of North America, vol. 20. Oxford University Press, New York-Oxford: 87-88.
Nesom G.L. (2007) Notes on the disarticulation of Xylothamia (Asteraceae: Astereae). J. Bot. Res. Inst. Texas 1:145-148.
Suh Y. & Simpson B.B. (1990) Phylogenetic Analysis of Chloroplast DNA in North American Gutierrezia and Related Genera (Asteraceae: Astereae). Syst. Bot. 15(4): 660-670.
Urbatsch L.E., Roberts R.P. & Karaman V. (2003) Phylogenetic evaluation of Xylothamia, Gundlachia, and related genera (Asteraceae, Astereae) based on ETS and ITS nrDNA sequence data. Am. J. Bot. 90(4): 634-649.