Arvensis is from the Latin arvum meaning cultivated field and refers to the plants association with cultivation.
Scarlet Pimpernel - because it has pink or red flowers.
Other Names:
Blue Pimpernel - a blue flowered variety.
Summary:
A hairless, weak stemmed, low growing, annual herb with square stems and opposite, egg shaped, stalkless leave. It has 5 petalled, scarlet or blue flowers from September to April.
Description:
Cotyledons:
Two. Triangular. 3-5mm. Hairless. Short stalk. Tip round. Sides straight angular to convex. Base tapered to squarish.
First leaves:
Oval. 5-10mm. Tip pointed. Hairless. Spotted underneath.
Leaves:
Opposite or sometimes in whorls of three leaves.
Petiole - None.
Blade - Light green. Oval to egg shaped. 5-25 by 5-20 mm. Tip pointed. Base squarish. Thin, hairless. Spotted with glands underneath. Sometimes dotted with black glands.
Stems:
Square with a wing on each corner. Up to 600 mm. Solid. Hairless. Branching from base. Weak, trailing. Initially erect, but droops with size. May root at nodes.
Flower head:
Single flowers in leaf axils.
Flowers:
Symmetrical, wheel like. 10-15 mm wide by 5 mm long. On stalks 15-30mm long that curve as fruit matures.
Bracts -
Ovary -
Sepals - 5. Green with pale edges, narrow and pointed. Free almost to the base. 3.5-5 mm long. Persistent.
Petals - 5. Pink/red or blue and darker or purple near the centre. Free almost to the base. Sometimes they are finely toothed and with glands on the edges. May be hairs near the tip. Fold up in dark or dull weather.
Stamens - 5. Filaments fringed with fine hairs and inserted on the base and opposite the petals.
Anthers -
Fruit:
Thin walled capsule. Spherical. Smooth. 4-5 mm. Releases seed by splitting around the middle with top lifting like a lid.
Seeds:
Many attached to a free, central, spherical placenta. Surface hairless, rough and dimpled. 1mm. Brown to black. Triangular pyramid shaped to three angled and elliptical.
Roots:
Key Characters:
Biology:
Life cycle:
Annual. Germinates autumn and spring. Flowers in spring.
Physiology:
Reproduction:
By seed.
Flowering times:
September to April.
Seed Biology and Germination:
Vegetative Propagules:
Hybrids:
Allelopathy:
Population Dynamics and Dispersal:
Germinate in autumn. On irrigated land they may also germinate in spring.
Origin and History:
Europe and temperate Asia.
Distribution:
ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
Habitats:
Climate:
Temperate, Mediterranean.
Soil:
Often in moist soils.
Plant Associations:
Significance:
Beneficial:
Fodder but not readily eaten.
Formerly used as a medicinal herb.
Detrimental:
Weed of pastures, irrigated pastures, crops, gardens, fallow and disturbed areas.
Toxicity:
Poisonous to sheep, cattle, horses, birds, dogs, rabbits and guinea pigs. Problems have been reported where little other feed is available or it was fed as a contaminant of chaff.
Contains a toxic volatile oil and glycoside. It is not cumulative.
It may only be toxic under certain conditions or for limited periods.
Generally it doesn't cause problems in the field.
Symptoms:
Gastro intestinal irritation, diarrhoea, constipation, nausea, loss of appetite, headache, body pain, depression, thirst and suspension of rumination.
Treatment:
Remove animals from infestation. Don't graze areas where there is little alternative feed.
Legislation:
None.
Management and Control:
Thresholds:
Eradication strategies:
Herbicide resistance:
Biological Control:
Related plants:
Chaffweed (Anagallis minima) has alternate leaves and tiny cream to pink leaves.
Plants of similar appearance:
Can be distinguished from Chickweed by the paired opposite leaves without petioles and square stems on Pimpernel.
Australian Crassula, Dense Crassula, Spreading Crassula (Crassula spp.)
Chickweed (Stellaria media)
Four-leaved Allseed (Polycarpon tetraphyllum)
Mouse-eared Chickweeds (Cerastium spp.)
Pearlwort (Sagina apetala)
Waterblinks (Montia spp.)
Pigweed (Portulaca spp.)
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P210. Photos.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P676-677. Diagram.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P300. Diagram.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P546-547. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P587-588.
Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P147-148. Diagram.
Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). p10-11. Photos.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P79. Diagrams.
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). #83.1.
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). P196.