Four-leaved Allseed

Polycarpon tetraphyllum (L.) L.

Family: Caryophyllaceae.

Names:

Polycarpon is from poly meaning many and karpos meaning fruit and refers to the large number of seeds produced.
Tetraphyllum is from tetra meaning four and phyllum meaning leaf (from the Greek phyllon) and refers to the groups of 4 leaves in rings on the stem.
Four-leaved Allseed because it has groups of 4 leaves and dense seed heads.

Summary:

A small, almost hairless, low lying annual to short lived perennial herb to 15 cm high, at first green but in summer turning reddish. Stipules at the base of the leaves are whitish and membranous. Leaves shortly stalked, opposite or appearing to be in whorls of 4, the blade spoon shaped with a rounded tip and 4-15 mm long. The white and green flowers are in dense terminal clusters, with 5 tiny white membranous petals 1-2 mm long which are shorter than the 5 greenish long-pointed sepals 1.5-3 mm long. The fruit is a small capsule splitting into 3 to release many small seeds.
Four-leaved Allseed is native to the Mediterranean region, now a common weed of gardens, wasteland, agricultural areas and disturbed bushland. It flowers in spring and summer. It is similar to many other species of the family Caryophyllaceae which have also been introduced to WA.

Description:

Cotyledons:

Two.

Leaves:

Opposite and appear to be in rings of 4 leaves in most varieties.
Stipules - Papery, short, white, translucent, narrowly egg shaped to triangular, 2-4 mm long. Joined with companion stipule but the tips are narrow and separate.
Petiole - Short, slender, merges with leaf.
Blade - Flat, dark green, egg to spoon shaped, 4-15 mm long x 2.5-7 mm wide. Edges translucent or with tiny teeth. Hairless or with tiny hairs on the midrib.

Stems:

Usually low lying or bending upwards at the ends or somewhat erect, 35-150 mm long, ridged. Hairless.

Flower head:

Many small flowers in dense or loose, many branched, terminal cymes

Flowers:

White, small, bisexual. On short stalks (pedicels) less than 3 mm long.
Bracts - Papery, white, translucent, narrowly egg shaped with an acute tip.
Ovary - 1 celled. 3 styles united near the base.
Sepals - 5, narrowly egg shaped, keeled, hooded, 1.5-3 mm long, papery edges. Short, sharp tip. Keel is leafy with fine teeth.
Petals - 5, white, narrowly oblong, tiny, 1-2 mm long, smooth edged, membranous, translucent. Almost hidden inside the calyx. Tip notched or tapering to a point.
Stamens - 3. Filaments joined at the base.
Anthers - Almost globular

Fruit:

Abundant, egg shaped capsules, shorter than and almost enclosed by the calyx, 1-2 mm long x 1 mm wide, opens by 3, spirally twisting valves, about 15 seeded.

Seeds:

Almost triangular or kidney shaped, brown seed, 0.5 mm long, white warts on the surface.

Roots:

Taproot.

Key Characters:

Stipules conspicuous.
Leaves opposite or whorled, obovate to almost circular
Petals minute
Sepals free, scarious margins, strongly keeled.
Styles 3 united towards the base.
Fruit a 1-2 mm long capsule, smaller than the sepals, opening by valves.
Many seeds.
Adapted from J.R. Wheeler and J.M. Black.

Biology:

Life cycle:

Annual, biennial or perennial. Seed germinates in autumn to winter and it grows over winter through to summer. It starts flowering in spring and continues into summer. It may produce a dense cover in moist, fertile areas.

Physiology:

Reproduction:

By seed.

Flowering times:

Spring to summer in western NSW.
Spring and summer in SA.
September to November in Perth.
Spring to summer in WA.

Seed Biology and Germination:

Vegetative Propagules:

None.

Hybrids:

Var. diphyllum has leaves in pairs with lanceolate stipules that are often half as long as the leaves and has a dense flower head.

Allelopathy:

Population Dynamics and Dispersal:

Spread by seed.

Origin and History:

Europe. Western Asia.

Distribution:

NSW, QLD, SA, TAS, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Prefers shady situations.

Climate:

Temperate. Mediterranean.

Soil:

River flats. Stony hillsides. Limestone soils.

Plant Associations:

Woodland communities.
Tuart woodlands.

Significance:

Beneficial:

Fodder, but tends to disappear under grazing.

Detrimental:

Weed of lawns, gardens, pastures, crops and disturbed areas.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Prevent seed set.
Graze the area.

Herbicide resistance:

Biological Control:

Related plants:

None.

Plants of similar appearance:

Australian Crassula, Dense Crassula, Spreading Crassula (Crassula spp.)
Chickweed (Stellaria media)
Mouse-eared Chickweeds (Cerastium spp.)
Pigweed (Portulaca spp.)
Pimpernel (Anagallis arvensis)
Waterblinks (Montia spp.)
Pearlwort (Sagina apetala)
Petty Spurge (Euphorbia peplus) exudes a white sap when damaged.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P144. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P357. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P303. Photo.

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). P130. Photo.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1000.1.

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). P106.

Acknowledgments:

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