Arvensis is from the Latin arvum meaning cultivated field and refers to the plants association with cultivation.
An annual herb with grey-green, 3 lobed, hairy leaves with cupped stipules and forming a loose rosette. The mature plant is erect or semi-erect when small but longer stems are prostrate. The stems branch from the base and normally reach 150 mm in length though under non-competitive conditions the plant is capable of growing to a very much larger size. It has tiny green flowers that turn red from August to September.
Two. The cotyledons are almost circular, hairless, with a slightly indented apex and approximately 3 mm in diameter. Tip rounded. Sides convex. Base tapered. Petiole shorter than the blade. The seedling has a very short hypocotyl and no epicotyl.
Leaves develop singly, the early leaves being approximately 10 mm overall in length of which approximately half is petiole. The upper leaf surface has slender hairs and there are few or no hairs on the lower surface. The initial leaf has three lobes.
Alternate. Later leaves become more lobed with the lobes sub-divided. The plant forms an untidy rosette 100 to 200 mm in diameter.
Stipules - Lobed and partly fused into a leaf like cup with 5-7, triangular, obtuse tipped lobes. Bristly hairs along the veins.
Petiole - About 2 mm long.
Blade - Grey-green, fan shaped. Deeply 3 lobed and these lobes divided at the top into 3-5 more toothed, oblong lobes, each 2-3 mm long. Long downy or bristly hairs. About 5 mm long. Base tapered to squarish to indented.
Stem leaves - The stem leaves are 5 to 10 mm long with stem clasping stipules, and have long downy hairs on the upper and lower surface.
The stem is circular in cross section, hollow, and carries long downy or bristly hairs. Usually about 150 mm long but may be much longer. Branch from the base. Bend upwards.
Flower stem -
Cymes almost hidden by stipules, opposite the leaves (extra axillary).
Green turning red, sessile and occur in small clusters in the leaf axils. They are unisexual, only 1 mm or thereabouts in diameter, and without petals.
Ovary - 1 carpel. Style basal. Stigma capitate.
Calyx - Persistent, 2.5 mm long, striped, constricted below 0.5 mm triangular lobes. Floral tube with scattered white hairs. Epicalyx segments smaller than sepals and inconspicuous.
Sepals - 4. Spreading, triangular.
Petals - None.
Stamens - 1 rarely 2.
Single achene, 1.25-1.5 mm long, enclosed in floral tube 2-2.5 mm long and usually protrudes beyond the stipules.
Annual. Germination occurs in the Autumn or Spring.
August to September.
Seed Biology and Germination:
Population Dynamics and Dispersal:
Spread by seed.
Origin and History:
NSW, TAS, VIC, WA.
Parsley Piert occurs throughout Tasmania being generally common in the North and North-West and locally common in the South.
Minor weed of crops.
Not recorded as toxic.
Management and Control:
In Tasmania, it can be found in most crops but is of little or no economic significance.
Plants of similar appearance:
The young plant has a superficial resemblance to Fumitory, Crowsfoot, Cotula, and Swinecress, but is readily differentiated from these by its circular and very small cotyledon, and by the shape of the leaves.
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P215. Diagrams.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P194. Diagram.
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). #106.1.
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). P208.