Senecio (ragwort) is the largest genus of flowering plants, with about 2000 species worldwide. There are 17 in Western Australia, six of them probably naturalised. For correct identification, see specialist texts. S. diaschides is an erect perennial to 1.2m, with few branches below the inflorescence, that consists of heads with yellow disc florets only. It is an aggressive coloniser of disturbed forest roadsides between Harvey and Pemberton. Flowers in spring. A native of eastern Australia, it may also be native here. S. elegans is a low-growing coastal species with stunning magenta ray florets. Itis found from Busselton to Albany and is originally from South Africa.

Senecio elegans , PH

S. glastifolius is an erect, much-branched small shrub to 1 m, with dentate oblong leaves and purple ray florets on long stalks. It is originally from South Africa and is found in banksia woodlands in the Albany area.

S. glastifolius , GK

S. jacobaea (ragwort) DP is an erect, hairless biennial to 1.5m, branching above to display the golden-rayed flower heads. Known from paddocks near Walpole. Native to Europe.

S. jacobaea , APB

S. lautus (variable groundsel) is a native yellow daisy, found throughout most of Australia; highly variable in leaf shape, stature and in the habitats in which it occurs. Around Perth and Rockingham, a particular form with lanceolate, slightly serrated leaves, behaves as a weed of road verges and pastures (where it tends to be left alone by grazing animals). The plants are usually unbranched, to about 40cm. The ray florets are 5-10mm long. Flowers in spring.

S. lautus, RC

S. tamoides (Canary creeper) is a bushy climber with large clusters of sweet-scented, yellow flowers. It has bright green, squarish, somewhat succulent leaves. It grows from offcuts and has been found on wasteland, associated with dumped garden rubbish, in Perth and along the south coast from Denmark to Ravensthorpe. Native to South Africa.

S. lautus, RC

S. vulgaris (groundsel) is an erect annual with irregularly lobed leaves and groups of small, nodding, cylindrical flower heads without ray florets. A common weed in summer-irrigated vegetable crops in the Swan Coastal Plain areas, also an occasional weed of gardens and disturbed areas from Perth to the Fitzgerald River National Park. Native of Europe.

S. vulgaris , PM

Sigesbeckia orientalis (Indian weed) is an upright, slightly hairy annual with opposite toothed leaves and small, yellow, daisy-like heads in the leaf axils. Found in forested areas between Perth and Albany, and in the Pilbara. A cosmopolitan plant.

Sigesbeckia orientalis , GK

Silybum marianum (variegated thistle) DP is an annual or biennial that first forms a rosette of leaves then sends up sparsely branched stems up to 2m. The large leaves are convoluted with prickly margins, and white patches on the upper surface give them a variegated appearance. The solitary, purple heads are surrounded by long spiny bracts. Flowers in late spring and early summer. An agricultural and forestry weed, commonly found in the lower south-west and also near Northampton. Native to southern Europe.

Silybum marianum , RK