1 / 12

Senecio madagascariensis

madagascar ragwort

Asteraceae Southern Africa and Madagascar

Overview

Senecio madagascariensis is an annual to short-lived perennial herb reaching 4-24 inches (10-60 cm) tall, branching from the base into a rounded form. Stems are slender, ribbed, and mostly hairless. Leaves are alternate, narrow, 1-2.8 inches (2.5-7 cm) long and up to 0.4 inch (1 cm) wide, with toothed or smooth margins and a stem-clasping base. Flower heads are yellow and daisy-like, about 0.8 inch (2 cm) across, typically carrying 13 ray florets around a central disc and subtended by about 21 narrow green bracts in a single row. Heads are borne singly or in loose clusters at the stem tips and appear through much of the year, with peak flowering in winter and spring in temperate Australia. Seeds are cylindrical, 0.06-0.1 inch (1.5-2.5 mm) long, each tipped with a white pappus that carries it on the wind, and a single plant can set several thousand seeds in a season. All parts contain pyrrolizidine alkaloids that are toxic to cattle and horses and accumulate in the liver. The species establishes quickly on disturbed and overgrazed ground and is regulated as an invasive weed across eastern Australia.

Native Range

Senecio madagascariensis is native to southern Africa and Madagascar, where it grows in grassland, open woodland, and disturbed sites. It has naturalised widely in Australia, South America, Japan, and Hawaii. In Australia it occupies coastal and tableland pastures, roadsides, and cultivated ground from Queensland to Victoria.

Suggested Uses

Senecio madagascariensis is not cultivated and has no horticultural use. It is listed as a noxious or restricted weed in New South Wales, Queensland, and other Australian jurisdictions, where its sale and movement are regulated. Land managers track it in grazing pasture because of its toxicity to cattle and horses.

How to Identify

Recognised by yellow daisy flower heads about 0.8 inch (2 cm) across with usually 13 ray florets and around 21 narrow green bracts in a single row at the base. Leaves are narrow with a slightly stem-clasping base and no leaf stalk. Distinguished from Senecio pinnatifolius by its narrower, less divided leaves and from native Senecio spp. species by the consistent count of about 21 bracts and 13 rays.

Appearance

Size & Dimensions

Height4" - 2'

Width/Spread8" - 1'8"

Colors

Flower Colors

yellow

Foliage Colors

green

Bloom Information

Bloom Period

~20 weeks

Winter Spring

Flowers appear through much of the year in frost-free areas, with peak bloom from winter into spring (June to November) in temperate eastern Australia. Individual heads last about 1-2 weeks before forming wind-borne seed. Flowering slows in hot, dry summer conditions and resumes after rain.

Detailed Descriptions

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-8 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

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Senecio madagascariensis grows in full sun on a wide range of soils, including poor and disturbed ground, and completes its life cycle within a single season. Seedlings emerge after autumn and spring rain and reach flowering size within 6-10 weeks. Plants tolerate dry spells once established but die back in prolonged drought. In pasture it spreads where grass cover is thin from overgrazing or cultivation. Control methods include removing plants before seed set and maintaining dense ground cover, while herbicides registered for the species are applied at the rosette stage. Livestock poisoning occurs when animals graze infested pasture over extended periods.

Pruning

Pruning is not applicable to this short-lived herb. Whole plants are removed by hand or cut at ground level before the flower heads mature, which limits seed dispersal. Cut material still carrying flower heads can continue to ripen viable seed.