Senecio interpositus
I.Thomps.Ascending or erect annual to 1.0 m high; stems sparsely appressed-cottony or ± glabrous. Leaves pseudopetiolate, attenuate at base; mid-stem leaves very narrow-elliptic, 6–12 cm long, to 15 mm wide, entire or more often coarse-dentate to lobate with remotely denticulate or dentate margins; upper leaves attenuate, very narrow-elliptic, or linear to narrow-linear; upper surface ± glabrous (in NSW plants) or sparsely appressed-cottony; lower surface ± glabrous. Inflorescences usually with 8–60 capitula; capitula non-radiate; involucre cylindric, 5.0–6.5 mm long, glabrous or cobwebby; bracts usually 11–14; bracteoles present; florets 25–50, all bisexual (not in Victorian plants) or bisexual and female. Cypselas cylindric or oblong-ellipsoid, 2.5–3.0 mm long, tan or dark brown, glabrous (in NSW plants) or papillose-hairy scattered in lines; pappus of slender hairs, 5–6 mm long, deciduous. Flowers summer–autumn.
NIS, HNF, VAlp. Also Qld, NSW, ACT. Rare in peaty clay soils sub-alpine swampy flats or grassland and in woodland at altitudes over 900 m throughout the alps.
This species is distinguished from other disciform species by the lower proportion of female florets in the capitula (up to c. 50% in this species compared to 70–80% in other disciform species). This feature as well as the reflexed phyllary apices at anthesis demonstrate a possible close relationship with the discoid species, Senecio georgianus and S. helichrysoides (Thompson 2004a).
