© Sula Vanderplank, some rights reserved (CC-BY) · iNaturalist
Overview
Polycarpon is a genus of small annual and short-lived herbs in the family Caryophyllaceae, with a near-cosmopolitan spread centred on the Mediterranean and warm temperate regions. The plants are low and much-branched, forming prostrate to low mounded mats 2-6 in (5-15 cm) high and a little wider, with slender stems that root where they touch moist ground. Small leaves are arranged in whorls or opposite pairs, and in Polycarpon tetraphyllum they appear in fours, giving the common name four-leaved allseed. Tiny greenish-white flowers, only 1-2 mm across, gather in dense forking clusters through summer and ripen into minute capsules that release numerous small seeds. The genus grows readily on poor, dry, sandy and gravelly ground, in paving joints, and on disturbed waste land. Plants are inconspicuous and weedy in habit, completing their life cycle within a season and self-sowing heavily. One limitation is its weedy nature, since it seeds heavily into paving and containers and has little ornamental presence.
Native Range
Polycarpon is native to the Mediterranean Basin and warm temperate parts of Europe, but several species have spread almost worldwide as weeds of cultivation. Plants grow on sandy soils, gravel, paving, coastal ground, and other open, disturbed sites.Suggested Uses
Grown chiefly in botanical and teaching collections, gravel gardens, and trough plantings where small Mediterranean annuals are studied. The mats can knit over bare gravel and paving joints. Plants are otherwise treated as a minor weed of cultivated ground.How to Identify
Appearance
Size & Dimensions
Height2" - 6"
Width/Spread4" - 10"
Bloom Information
Flowering extends through the warm months, roughly May to October, with overlapping generations in mild areas. The greenish-white flowers are tiny and easily overlooked, opening continuously in branched clusters. Seed sets quickly and abundantly after each flush.
Detailed Descriptions
Foliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Drought Tolerance
Drought tolerant when established
Care & Maintenance
Care Guide
Polycarpon grows in full sun on light, sharply drained sandy or gravelly soils across a wide pH range from about 5.5 to 8.0. It tolerates heat, drought, and poor ground, and needs no feeding or irrigation once seedlings are up. Plants are raised, where wanted, by scattering seed on warm, open soil in spring. Damp, rich, or shaded sites are tolerated poorly and shorten the plant. Self-sown seedlings appear readily and can spread into paving and pots. The genus is frost-tender and dies with the first hard freeze.Pruning
No pruning is needed. Plants are pulled or hoed out once flowering ends or where self-seeding spreads them beyond their place. Clearing the mats before capsules ripen limits the spread of seed.Toxicity
Non-toxicPlanting Guide
Planting Methods & Timing
Planting Method
direct sow
Direct Sow Timing
spring, on warm soil
Days to Maturity
50–80 days
Plant Spacing
6 inches