Senecio is from the Latin senex meaning old man and refers to the beard like pappus on the seed.
Cotton Fireweed refers to cotton woolly appearance of the plant and fireweed refers to the large stands that often establish after burning.
Erect, bushy, white woolly, many stemmed annual to short lived perennial herb with long slender leaves and branched, yellow flowered heads on top.
Petiole - None.
Blade - Silver grey, parallel sided to narrowly oval, 15-200 mm long by 2-14 mm wide, sometimes has tiny teeth or lumps towards the tip which may be hidden by the in-rolled edge. Sometimes has small parallel sided clasping lobes where leaf joins stem. Edges usually rolled in. Tip pointed. White woolly hairs on the underside of the leaves.
Stem leaves - Upper leaves sometimes with stem clasping lobes.
Silver grey, erect, striped, 300-800 mm tall. Usually many arising from the base, almost tufted, with a few, erect branches below the flower head. Grey woolly hairs when young, becoming hairless with age. Stems becomes woody at the base with age.
Loose, corymbose cyme or panicle. Green or yellowish. At ends of branches or in leaf axils. Flower base(involucre), 7-10 mm long, slender, cylindrical, 10-14 bracts.
Yellow or yellow-green.
Bracts - 10-14 in a single row, 6.5-8 mm long by 0.4-2 mm wide, tips pointed and becoming hairless with age, 2 veined and conspicuous on the lower third.
Florets - Yellow, scarcely longer than the flower base(involucre). 5-10 outer flowers in 2-3 rows, thread like, 3-4 toothed, female. Central florets around 20-35, bisexual, tubular, 4-5 toothed.
'Petals' - none.
Red to dark green brown achene, 2.5-5 mm long, cylindrical, slightly curved, tapering toward the end almost into a beak, narrow grooves between flattened ribs with short, white, low lying hairs in the grooves. Pappus of slender white hairs about 1.5 times longer than the achene and sticking out of the flower head.
With a white hairy pappus, 4-6mm long.
Erect more or less tufted herb.
Annual or short lived perennial.
Leaves linear or linear-lanceolate, mostly entire sometimes minutely denticulate, greyish woolly-hairy below.
Involucre cylindrical, with about 12 bracts.
Flower heads heterogamous-discoid.
Outer flowers in 2-3 rows, filiform, female, 3-4 toothed.
Inner flowers tubular, bisexual.
Flowers scarcely exceed the involucre.
Achenes 3-4 mm long, usually much attenuate above and almost beaked.
From J.M. Black, N.T. Burbidge and N.S. Lander.
Annual or short lived perennial. Seeds germinate mainly in autumn and it grows mainly in winter. It flowers from spring to autumn. Top growth often dies off over summer leaving a perennial rootstock, which shoots in autumn
Spring in western NSW.
Summer in SA.
September to December in Perth.
September to June in WA.
Seed Biology and Germination:
Perennial root system.
Population Dynamics and Dispersal:
Common after fire and on new land. Tends to decrease with time after clearing. It may quickly over-run a pasture and then a few years later almost disappear.
It often increases after fertilising with superphosphate, lime or gypsum.
Origin and History:
Australia, New Zealand, New Caledonia, Timor.
ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
Adapted to a wide range of habitats.
Many soil types.
Dry sclerophyll areas. Open woodland.
Fodder but fairly unpalatable and usually only grazed when other feed is limited.
Weed of crops, pastures, fence lines, roadsides and disturbed areas.
Toxic to cattle but usually only a problem when there is little other feed.
Alkaloids affect the liver and lungs.
Loss of condition, chronic scouring, breathe with a roaring noise when driven, sudden death. Deaths in a herd are often intermittent.
Provide alternative feed in infested areas.
Management and Control:
Difficult to control with herbicides.
Use adjuvants to improve the wetting of the plant with herbicide.
African Daisy (Senecio pterophorus)
Bushy Groundsel (Senecio cunninghamii)
Cape Ivy (Senecio angulatus)
Cape Ivy (Senecio mikanioides)
Common Groundsel. (Senecio vulgaris)
Commonwealth weed (Senecio bipinnatisectus)
Feathery Groundsel (Senecio anethifolius)
Fireweed (Senecio lautus)
Fireweed Groundsel (Senecio linearifolius)
Fleshy Groundsel (Senecio gregorii)
Hispid Fireweed (Senecio hispidulus)
Holly-leaved Senecio (Senecio glastifolius)
Mountain Fireweed (Senecio gunnii) is similar but has stolons.
Purple Groundsel (Senecio elegans)
Ragwort (Senecio jacobaea)
Slender Groundsel (Senecio glossanthus)
Squarrose Fireweed (Senecio squarrosus)
Tall Groundsel (Senecio runcinifolius)
Tall Yellowtop (Senecio magnificus)
Plants of similar appearance:
Cudweed (Pseudognaphalium luteo-album).
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P114. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P888.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P375.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P679. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P184.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1125.8.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P704.