Fleshy Groundsel, Yellow-tops, Annual Yellow-top.

Annuals to c. 0.5 m high, glaucous, glabrous. Leaves to 10 cm long, with l: w ratio c. 15–20, undivided; base attenuate, without auricles; margin entire. Capitula 1 or few per stem, ecalyculate; involucre 8–16 mm long, c. 5–9 mm diam., with secondary capitula often much smaller; bracts c. 13, all or mostly fused except at apices, finally split into 3 or 4 sections. Florets numerous; ligulate florets 7–11; ligule 12–20 mm long, 4–6-veined; disc florets with corolla limb much shorter than tube. Achenes obloid, 4–7 mm long, ribbed, with papillose hairs obscuring much of surface; l:w ratio of hairs c. 20; ray achenes sometimes underdeveloped. Pappus persistent, 10–30 mm long; bristles smooth, rather stout proximally.

Flowers most of year.

n = 20, M.E. Lawrence, Australian Journal of Botany 28: 153 (1980).

Native.

Occurs from Carnarvon, Western Australia, through southern Northern Territory east to Blackall in central Queensland, and south to the Whyalla area, South Australia, western New South Wales and as far south as the Big Desert area in northwestern Victoria.

Grows in various soils in river beds, plains, dunes and saline swamp margins, in herbfield, shrubland and woodland.

W.A.: c. 56 km W of Docker River on road to Giles Weather Station, 11 Aug. 1986, K. Menkhorst s.n. (MEL, PERTH).

N.T.: c. 16 km WNW of Santa Teresa Mission, M. Lazarides 5732 (CANB, DNA).

S.A.: E side of road, 75 km N of Glendampo on Stuart Highway, J.R. Shelley 27 & R. McCullough (AD, CANB, MEL, PERTH).

Qld: on Birdsville Road, 5 km W of Betoota, K.A. Williams 78171 (AD, BRI).

N.S.W.: 8.5 km SE of Fort Grey campsite turnoff en route to Tibooburra in Sturt National Park, R.G. Coveny 13498 et al. (AD, BRI, CANB, MEL, NSW).

Vic.: 400 m S of Meridian Gate, Wyperfeld National Park, 24 Aug. 1983, D.C. Cheal (MEL).

An unusual species with several apparently unique features, although it is similar to several other radiate Australian taxa of arid or semiarid regions. Also superficially similar to members of the southern African genus Othonna, in which it was placed in 1986. Closest affinity is with Senecio conferruminatus based on involucre morphology. It possibly also has affinity to S. gypsicola, based on fusion of involucral bracts, and to S. platylepis, based on achene morphology. Readily recognised by the involucre of fused bracts, the absence of calycular bracteoles, the large achenes with an indumentum of long hairs, and the very long, basally-stout pappus bristles. Style branches are long and their apex has a crown of rather long clear narrowly triangular papillae. Capitulum size varies considerably on individuals with later-developing capitula often much smaller. This feature also occurs in S. conferruminatus.

Another similarity between S. gregorii and S. conferruminatus, which distinguishes them from the other members of the Magnificus group, is the morphology of the corolla of the disc florets. The limb is markedly shorter than the tube and the balusterform (flared) base of the tube is elongate. In contrast, the base is not elongate in other species, the limb in S. magnificus and S. megaglossus is longer than the tube, and in most other species it is c. as long as the tube. Senecio gypsicola is an exception, in that the limb in this species is commonly slightly shorter than the tube.

K.A.W. Williams, Native Plants of Queensland 3rd edn, 1: 258–259 (1984); J.P. Jessop & H.R. Toelken (eds), Flora of South Australia 4th edn, 3: 1595, fig. 725E (1986); N.G. Walsh & T.J. Entwisle (eds), Flora of Victoria 4: 946, fig. 193a (1999); I.R. Thompson, Muelleria 20: 114, fig. 1a; 116, fig. 3 (2004); F. Kutsche et al., Field Guide to the Plants of Outback South Australia 2nd edn: 214 (2023).

Kutsche, F., Lay, B., Croft, T. & Kellermann, J. (2023). Field Guide to the Plants of Outback South Australia 2nd revised edn. (State Herbarium of South Australia: Adelaide).

Lawrence, M.E. & Belcher, R.O. (1986). Senecio, in Jessop, J.P. & Toelken, H.R. (eds), Flora of South Australia 4th edn, 3: 1591–1605.

Thompson, I.R. (2015). Senecio, in Wilson, A.J.G. (ed.), Flora of Australia 37: 209–307. (Australian Biological Resources Study: Canberra).

Flora of Australia Volume 37 (2015).