Potato weed

Galinsoga parviflora Cav.

Family: Asteraceae.

Names:

Galinsoga honours the Mariano Martinez Galinsoga, the Director of the Botanical Garden of Madrid in the late 18th century.
Potato weed because it resembles a potato plant.

Other names:

Gallant Soldiers
Yellow weed because it has yellow flowers.

Summary:

An erect almost hairless annual herb, 300-600 mm tall with opposite, oval, usually toothed leaves and small yellow flowers with a few, short lived, white petals in spring.

Description:

Cotyledons:

Two.

Leaves:

Opposite.
Stipules -
Petiole - Slender with low lying hairs or fine glandular hairs.
Blade - Pale green, egg shaped to narrowly egg shape, 20-70 mm long x 12-40 mm wide, thin. Pointed tip. Sides convex and usually toothed. Base tapered to squarish. Surface hairless or slightly hairy with hairs held close to the surface. On the lower surface hairs are restricted to veins.

Stems:

Erect or bending upwards at the ends, 300-600 mm tall, soft, slender, many branched. Hairless to slightly hairy.

Flower head:

Many heads in a small, diffuse, leafy corymb or cyme. Heads almost hemispherical, 3-5 mm wide. Bracts egg shaped, hairless with green veins in several rows, about 5 on the innermost row, egg shaped and slightly concave. Outer rows smaller, narrower and usually only 1-3. Many flower heads on long, glandular hairy, slender stalks in leafy cymes of upper axils or at the ends of stems.

Flowers:

Florets - Outer (ray) florets white, often 5. 'Petal' (ligule) white, short, 3 lobed, female and fertile.
Inner (disc) florets yellow, bisexual, tubular, many.
Ovary - Style branches with acute tips. Conical receptacle. Scales often split in 2 or 3 for about half their length between the disk florets.
'Petals' - White, short, 3 lobed.
Stamens -
Anthers -
The few small ligules usually fall off giving the appearance of a head with only tubular flowers.

Fruit:

Black, achene, 4 angled, 1-1.5 mm long, egg shaped or top shaped, swollen near the top. Scattered white bristles. Pappus of disc florets are 6-22, translucent, lance shaped, feathery scales, shorter than the seed (achene). Seed of ray florets have no pappus or a few tiny bristles.

Seeds:

Roots:

Key Characters:

Yellow flowers.
Opposite leaves, usually toothed.

Biology:

Life cycle:

Annual. Flowers June to December.

Physiology:

Reproduction:

By seed.

Flowering times:

June to December in Perth.

Seed Biology and Germination:

Vegetative Propagules:

None.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

South America.

Distribution:

ACT, NSW, QLD, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Damp areas.

Climate:

Temperate.

Soil:

Plant Associations:

Significance:

Beneficial:

Detrimental:

Weed of cultivation, vegetables, gardens, disturbed areas, wet areas and roadsides.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

None.

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P102. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P877. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P367-368. 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). P98-99. Photo.

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). #570.1.

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). P679.

Acknowledgments:

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