1 / 10

Cyanthillium cinereum

little ironweed

Attracts Pollinators Attracts Butterflies

WaterLow

Overview

Cyanthillium cinereum is an erect annual herb growing 8-39 inches (20-100 cm) tall on slender, branching stems covered in short grey hairs. Leaves are alternate, ovate to lance-shaped, 0.4-2.8 inches (1-7 cm) long, with toothed or wavy margins and a greyish cast from short hairs on both surfaces, the lower surface paler. Small flower heads, each 0.2 inches (4-5 mm) across, are carried in loose branched clusters at the stem tips, and each head holds 15-20 mauve to pink-purple disc florets. Flowering can occur through much of the year in warm climates. Seeds are small dry achenes 0.06-0.1 inches (1.5-2.5 mm) long, topped with a tuft of white bristles that carries them on the wind. A single plant produces several hundred to several thousand seeds, and germination follows rain, allowing rapid colonisation of bare ground. The taproot is shallow and easily pulled. Plants complete their life cycle in a single growing season and die after seeding.

Native Range

Native to the tropics of Africa and Asia and widely naturalised across tropical and subtropical regions, including northern Australia and the Pacific. Grows as a weed of roadsides, cultivated ground, lawns, and other disturbed open sites from sea level to about 6,500 feet (2,000 m).

Suggested Uses

Rarely grown deliberately, it appears mainly as a volunteer in disturbed ground and is recorded in traditional herbal use across its range. Where present in managed areas it is treated as a weed and removed at the seedling stage. It has little role in ornamental planting.

How to Identify

Identified by slender hairy stems and grey-green toothed leaves that are paler beneath. The small flower heads, 0.2 inches (4-5 mm) across, contain only mauve to pink-purple disc florets and no ray florets, separating it from daisies that carry petal-like rays. The white-bristled seed tufts and overall greyish, hairy texture distinguish it from green-leaved Asteraceae spp. weeds of similar size.

Appearance

Size & Dimensions

Height8" - 3'3"

Width/Spread6" - 1'6"

Colors

Flower Colors

purple

pink

Foliage Colors

green

Bloom Information

Bloom Period

~12 weeks

Summer Fall

Flowers over an extended period, mainly in the warmer and wetter months, and nearly year-round in frost-free tropical areas. Individual heads open over several days, with a plant flowering and setting seed continuously for many weeks. Cooler or drier conditions shorten the flowering window.

Detailed Descriptions

Flower Description

mauve to pink-purple

Foliage Description

grey-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

clay loam sand

Drainageaverage

Water & Climate

Water Needs

Low

Care & Maintenance

Care Guide

Grows in full sun on a wide range of soils, tolerating poor, compacted, and disturbed ground. Establishes from seed without supplementary water in regions with regular rainfall, though prolonged drought ends the life cycle early. No fertiliser is needed, and plants persist on low-nutrient soils. Self-seeding is heavy, and volunteer seedlings appear after each rain unless seed heads are removed before they mature. The species is treated as a weed in many regions and spreads into lawns, crops, and gardens. It has no significant pest or disease problems.

Pruning

Pruning is not practised on this short-lived herb. Plants may be cut or pulled before flowering to limit seed set, since removal after seeding does little to reduce spread. Whole plants die back naturally once seeding is complete.