Note on Arrhenechthites haplogyna (Asteraceae)

Arrhenechthites haplogyna (F. Mueller) Mattfeld was originally described as Senecio haplogynus F. Mueller (Trans. Roy. Soc. Victoria 1, 1899: 14), based on rather poor material collected by Sir William MacGregor from Mount Knutsford. Von Mueller remarks that the species could be placed both in Senecio or Erechthites, basing himself on the statement by Bentham and Hooker in the Genera Plantarum 2 (1873) 208, ‘that occasionally some solely pistillate flowers occur in species of Senecio, hence the only characteristic which separates Erechthites from Senecio, is unreliable, and therefore the present plant may be placed in either genus’. Mattfeld (Bot. Jahrb. 69, 1938: 292) creates a new genus, Arrhenechthites, and moves Senecio haplogynus into this genus, after originally having it placed in Erechthites (Bot. Jahrb. 62, 1929: 442). The grounds on which Arrhenechthites is distinguished in the first place from Erechthites, and secondly from Senecio, are rather flimsy but distinct. From both Arrhenechthites differs in having all marginal florets fertile but having sterile ovaries in the disk florets. The genus Erechthites differs from Senecio by having style arms with a crown of divergent hairs surrounding an appendage of fused papillose hairs. In Senecio this same crown of divergent hairs is present but the tips of the style arms are truncate or bluntly appendaged. Applying these data to von Muellers species it is clear that it is a species of Arrhenechthites and not a Senecio.