A New Hybrid, Crepidiastrum ×semiauriculatum (Asteraceae:Lactuceae), from Okayama Prefecture, Western Japan

Abstract

A putative hybrid between Crepidiastrum denticulatum (Houtt.) J. H. Pak & Kawano and C. yoshinoi (Makino) J. H. Pak & Kawano, Crepidiastrum xsemiauriculatum N. Yamam. & H. Ikeda (Asteraceae: Lactuceae), is described from a limestone area in Okayama Prefecture, western Japan. This plant differs from the presumed parents by the semi-auriculate base of the inflorescence bracts (deeply auriculate in C. denticulatum and attenuate in C. yoshinoi), and intermediate state of several characters of the flowers and fruits: florets 6-8 per capitulum (11-15 in C. denticulatum and 5 in C. yoshinoi), ligules 8.5-9.0 mm long (7.8-8.3 mm in C. denticulatum and 9.0-9.3 mm in C. yoshinoi), and achenes 3.8-4.3 mm long (3.2-3.8 mm in C. denticulatum and 4.5-5.0 mm in C. yoshinoi).