Purple Groundsel

Senecio elegans L.

Family: - Asteraceae

Names:

Senecio is from the Latin senex meaning old man and refers to the beard like pappus on the seed.
Elegans refers to the elegant flower.
Purple Groundsel refers to the purple colour of the flower and its membership of the Groundsel or Senecio genus.

Other Names:

Purple Ragwort.

Summary:

An short, erect, leafy, annual daisy of coastal sand dunes with clusters of deep pink to bright purple flowers with yellow centres from spring to summer. The outer florets have radiating petal-like blades while the inner florets are tubular. It has toothed to deeply dissected leaves. The tiny fruits are topped by many silky bristles.
Originating from South Africa, Purple Groundsel is now a weed in sand dunes along the south coast.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Alternate.
Stipules - None.
Petiole - None.
Blade - Stem clasping, toothed to deeply dissected, variable shape, usually 50-100 mm long by 15-50 mm wide. Hairy.

Stems:

Stout, erect, 300-1000 mm tall, ribbed, somewhat woody. Sparsely hairy.

Flower head:

Loose clusters (corymbs) of "flowers" with bell shaped bases that are 10-15 mm diameter. Branches 20-150 mm long.
12-15 main bracts, 5-10 mm long with many (10-20) small black tipped ones at the base.

Flowers:

12-17 purple to pink "petals" with a yellow centre.
Disk florets - tiny, tubular, bisexual, 5 toothed.
Ray florets - female, in a single row with large purple "petals" (rays).
Ovary -
Style branches flat topped, threadlike.
Petals - Rays are purple to pink, 15-20 mm long.
Stamens -
Anthers - Obtuse to shortly tailed

Fruit:

Achene, 2 mm long. Cylindrical, striped.

Seeds:

Seed has white silky 6-8 mm long, non persistent bristles on top that fall off easily.

Roots:

Taproot.

Key Characters:

Erect leafy annual.
Flowers heads corymbose.
Flower heads heterogamous-radiate,
Involucre bracts free, in 1 row with an outer calyx of very small black tipped bracts at their base
Receptacle naked.
Outer florets in a single row, ligulate, female.
Disk florets bisexual and more numerous than female florets.
Ligules purple, spreading and conspicuous.
Style branches truncate with a tuft of collecting hairs above the stigmatic lines.
Pappus silky.
Adapted from John Black and Gwen Harden.

Biology:

Life cycle:

Annual.

Physiology:

Tolerant of salt spray.

Reproduction:

By seed.

Flowering times:

Spring and early summer on the south coast of WA.
Summer in SA.
Summer in NSW.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread by wind blown seed.

Origin and History:

South Africa.

Distribution:

ACT, NSW, SA, TAS, VIC, WA
In WA it is on coastal dune areas from Ledge Point (north of Perth) to Two Peoples Bay (east of Albany).
Lord Howe Island, New Zealand, USA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate coastal.

Soil:

Sands.

Plant Associations:

Coastal scrub.

Significance:

Beneficial:

Ornamental.

Detrimental:

Weed of coastal sand dunes.

Toxicity:

None reported but other members of this genus cause liver problems.

Legislation:

None.

Management and Control:

Mowing, grazing or Spray Grazing with 2,4-D amine usually provides adequate control in pastures.

Thresholds:

Eradication strategies:

Hand pulling the plants in spring before flowering for a few years should provide control. Flowering plants need to be bagged and burnt as seed will mature on nutrient reserves within the stems.
Lontrel®750 at 200 g/ha applied before stem elongation in late spring provides reasonably selective control in coastal heath and bushland. For hand spraying use 4 g Lontrel®750 in 10 L water.
Small infestations can be treated with 100 mL Tordon®75-D in 10 L water which will control the plants and leave a soil residue for control of later emerging seedlings.
Cultivation and grazing provides reasonable control but is not generally appropriate in the dunes where it most often occurs.
New infestations in bushland tend to establish after disturbance or fire.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Bushy Groundsel (Senecio cunninghamii)
Cape Ivy (Senecio angulatus)
Cape Ivy (Senecio mikanioides)
Common Groundsel. (Senecio vulgaris)
Commonwealth weed (Senecio bipinnatisectus)
Cotton Fireweed (Senecio quadridentatus)
Feathery Groundsel (Senecio anethifolius)
Fireweed (Senecio lautus)
Fireweed Groundsel (Senecio linearifolius)
Fleshy Groundsel (Senecio gregorii)
Hispid Fireweed (Senecio hispidulus)
Holly-leaved Senecio (Senecio glastifolius) has toothed leaves, is usually larger, up to 2 m tall and more shrubby. It may have more “petals”. There are 12-22 petals on S. glastifolius and 12-17 on S. elegans.
Mountain Fireweed (Senecio gunnii)
Ragwort (Senecio jacobaea)
Slender Groundsel (Senecio glossanthus)
Squarrose Fireweed (Senecio squarrosus)
Tall Groundsel (Senecio runcinifolius)
Tall Yellowtop (Senecio magnificus)
Senecio daltonii
Senecio madagascariensis
Senecio megaglossus
Senecio tamoides

Plants of similar appearance:

Holly-leaved Senecio (Senecio glastifolius) is a perennial and much taller with toothed rather than lobed leaves and the bracts under the flower don't have a tiny dark tip.
Nearly all our native species of Senecio have yellow flowers, except Senecio leucoglossus which has white to pale purple flowers.

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P885.

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 3. P312. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P104. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #919.5.

Moore, J.H. and Wheeler, J.R. (2002). Southern Weeds and their Control. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.