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Spermacoce verticillata

shrubby false buttonweed

Rubiaceae

Tropical America (West Indies and South America)

Attracts Pollinators Attracts Butterflies Drought Tolerant

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 9–11

Overview

Spermacoce verticillata, shrubby false buttonweed, is a wiry perennial subshrub in the madder family, growing 1-3 feet (30-90 cm) tall with stiff, four-angled, much-branched stems that become woody at the base. The narrow, linear to lance-shaped leaves are 0.5-2 inches (1.5-5 cm) long, borne in opposite pairs with smaller leaves clustered in the axils, giving a whorled look at each node. Tight, button-like heads of tiny white tubular flowers sit in the leaf axils along the stems through much of the year. Each flower is about 0.1 inch (3 mm) long, and the heads ripen to clusters of small dry capsules. Native to the West Indies and tropical South America, S. verticillata has naturalized across the southeastern United States, Africa, and Asia, where it colonizes roadsides, pastures, sandy fields, and disturbed ground and is treated as an invasive weed in Florida. It tolerates heat, drought, and poor sandy soil once established. One limitation is its weedy spread by abundant seed, which lets it crowd out low vegetation on open ground. The white flower heads draw small bees and butterflies.

Native Range

Spermacoce verticillata is native to the West Indies and tropical South America. It has naturalized widely through the southeastern United States, sub-Saharan Africa, and tropical Asia, growing on sandy roadsides, pastures, and disturbed open ground.

Suggested Uses

Spermacoce verticillata is little used in ornamental planting and is mainly managed as a weed of pastures, roadsides, and sandy fields. In parts of its range it is grazed as rough forage and used as ground cover on poor soils. The small white flowers support bees and other insects in warm climates.

How to Identify

Look for a wiry subshrub with four-angled stems and narrow leaves in opposite pairs, with extra small leaves clustered at the nodes for a whorled effect. Dense, button-like heads of tiny white flowers sit tight in the leaf axils. The whorled nodes and stalkless white flower clusters separate it from Richardia spp. and other madder-family weeds with stalked heads.

Appearance

Size & Dimensions

Height1' - 3'

Width/Spread1' - 2'

Colors

Flower Colors

white

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~28 weeks

Spring Summer Fall

In frost-free climates S. verticillata flowers nearly year-round, slowing only in cool spells. In subtropical areas the main flush runs from late spring through autumn. Small dry capsules ripen within weeks and split to release the seed.

Detailed Descriptions

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun

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

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

sand loam

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

tender

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Spermacoce verticillata grows in full sun on dry, sandy, well-drained soils across a pH of about 5.5 to 7.5 and tolerates poor, infertile ground. It is frost-tender, persisting as a perennial in zones 9 to 11 and behaving as an annual where frost cuts it back. Established plants withstand heat and drought and need little water. The woody base resprouts after cutting or light frost. It self-sows heavily from a large seed crop and colonizes bare, sandy ground. Rich, wet soils and shade reduce its vigour.

Pruning

S. verticillata is cut back to keep it compact and to remove frost-killed stems, regrowing from the woody base. Shearing before the heads set seed reduces self-sowing. No detailed shaping is needed for this weedy subshrub.