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Urena lobata

caesar weed

Malvaceae Tropical Asia

Attracts Pollinators Drought Tolerant

SunFull Sun – Part Shade

WaterMedium · drought-tolerant

HardinessZones 9–12

Overview

Urena lobata is a woody-based perennial subshrub in the mallow family, reaching 3-10 feet (0.9-3 m) tall with slender, branching, star-hairy stems. The alternate leaves are 1.5-4 inches (4-10 cm) long, rounded to shallowly 3-7 lobed, dark green above and grey-velvety beneath, each leaf bearing a small gland on the midrib. Solitary pink flowers 0.5-0.75 inch (12-20 mm) across open in the leaf axils, with five notched petals and the fused staminal column typical of the family. The flowers give way to small segmented burrs about 0.3 inch (7 mm) wide, densely covered in hooked, barbed spines that cling to fur, feathers, and clothing and carry the seed long distances. Native to tropical Asia, U. lobata has spread through the tropics and subtropics, where it colonizes roadsides, pastures, and clearings and is treated as an invasive weed in Florida, Hawaii, and parts of Australia. The stems yield a strong bast fibre, marketed as aramina or Congo jute, and the species is grown commercially for cordage in parts of Africa, Brazil, and the Congo Basin. One limitation is that the clinging burrs foul livestock coats and contaminate wool.

Native Range

Urena lobata is native to tropical Asia, including India, southern China, and Southeast Asia. It has naturalized throughout the tropics and warmer subtropics of Africa, the Americas, and the Pacific, and is recorded as invasive in Florida, Hawaii, and northern Australia.

Suggested Uses

Urena lobata is grown commercially for its bast fibre, used in sacking, cordage, and twine. In its native range the roots and leaves are used in traditional herbal preparations. Elsewhere it is managed as a pasture and roadside weed rather than planted.

How to Identify

Look for a tall mallow subshrub with grey-velvety, shallowly lobed leaves that carry a small gland on the underside midrib. The pink five-petalled flowers are about 0.5-0.75 inch (12-20 mm) wide. The clustered, bristly burrs covered in hooked spines confirm identity and separate it from Sida spp. and Malvastrum spp. relatives.

Appearance

Size & Dimensions

Height3' - 10'

Width/Spread2' - 4'

Colors

Flower Colors

pink

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~20 weeks

Summer Fall

In tropical climates U. lobata flowers nearly year-round, peaking in the wet season. In subtropical areas flowering concentrates from summer into autumn. Each pink flower lasts about a day, and burrs ripen within a few weeks of pollination.

Detailed Descriptions

Foliage Description

dark green above, grey-green beneath

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-10 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

loam sand clay

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Urena lobata grows in full sun to part shade on moist, fertile loams but tolerates poor, sandy, and seasonally dry soils across a pH of about 5.5 to 7.5. It is frost-tender and grows as a perennial only in zones 9 to 12, behaving as an annual where winters are cold. Established plants withstand short drought once the woody base forms. The species self-sows freely from burr-borne seed and regrows from the crown after cutting. It establishes on disturbed, open ground and along watercourses. Waterlogged soils slow growth.

Pruning

Cutting the stems back stimulates basal regrowth, so single cuts rarely kill established plants. Where grown for fibre, stems are harvested at flowering when bast yield peaks. In weed settings, repeated cutting before the burrs form limits seed spread.