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Scientific Name
Synonyms
Family
Common Names
Origin
Naturalised Distribution
Habitat
Habit
Distinguishing Features
Stems and Leaves
Flowers and Fruit
Reproduction and Dispersal
Environmental Impact
Legislation
Management
Similar Species
Print Fact Sheet
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Click on images to enlarge

infestation (Photo: Sheldon Navie)

habit prior to flowering (Photo: Sheldon Navie)

habit in flower (Photo: Sheldon Navie)

close-up of whitish hairy stems (Photo: Sheldon Navie)

hairy leaves with a crinkled appearance (Photo: Sheldon Navie)

dense flower clusters in the leaf forks (Photo: Sheldon Navie)

clusters of immature fruit (Photo: Sheldon Navie)

close-up of mature fruit with curved teeth (Photo: Sheldon Navie)

close-up of seeds (Photo: Steve Hurst at USDA PLANTS Database)

young plant (Photo: Sheldon Navie)

close-up of the larva of the horehound plume moth, Pterophorus spilodactylus (Photo: Sheldon Navie)

close-up of flowers, with two-lobed upper 'lips' and three-lobed lower 'lips' (Photo: Sheldon Navie)

Marrubium vulgare

Scientific Name

Marrubium vulgare L.

Synonyms

Marrubium album Gilib.
Prasium marrubium Krause

Family

Labiatae (South Australia)
Lamiaceae (Queensland, New South Wales, the ACT, Victoria, Tasmania, Western Australia and the Northern Territory)

Common Names

common horehound, hoarhound, horehound, hound's bane, houndsbane, marrube, marvel, white horehound, woolly horehound

Origin

This species is native to southern and western Europe, western and central Asia (i.e. Eurasia) and northern Africa.

Naturalised Distribution

A widely naturalised species that is found largely throughout the southern and eastern parts of the country. It is most common and widespread in New South Wales, the ACT, Victoria, Tasmania and the southern regions of South Australia. Also relatively common in the southern parts of Western Australia, scattered throughout southern and central Queensland, and naturalised on Norfolk Island.

Habitat

A weed of temperate, semi-arid and occasionally also sub-tropical regions. It is found along roadsides, railways, fence lines, waterways, and in waste areas, disturbed sites, gardens, pastures, grasslands, open woodlands and sometimes also in crops.

Habit

An upright (i.e. erect or ascending) or spreading (i.e. decumbent), long-lived (i.e. perennial), herbaceous plant. It usually grows 20-60 cm tall, but rarely reaches up to 1 m in height.

Distinguishing Features

Stems and Leaves

The stems are much branched, particularly towards the woody base of the plant, and roots (i.e. adventitious roots) can be produced from the lowest stem joints (i.e. nodes). These stems are square in cross-section (i.e. quadrangular) and densely covered with whitish coloured hairs (i.e. tomentose).

The oppositely arranged leaves are also covered in whitish hairs (i.e. tomentose), particularly on their undersides. Lower leaves have longer leaf stalks (i.e. petioles) than the upper leaves, with stalks usually from 10-25 mm long. These leaves (10-70 mm long and 8-45 mm wide) are egg-shaped in outline (i.e. ovate) or almost rounded (i.e. orbicular) and somewhat crinkled (i.e. rugose) in appearance. They also have bluntly toothed (i.e. crenate) margins and rounded tips (i.e. obtuse apices).

Flowers and Fruit

The white tubular flowers (6-12 mm long) are borne in dense clusters in the forks (i.e. axils) of the upper leaves. Flowers are two-lipped (i.e. bi-labiate), the upper 'lip' being divided into two lobes and the lower 'lip' being divided into three lobes. These flowers are surrounded by a persistent green tube (4-7 mm long) made up of the fused sepals. Flowering occurs throughout the year, but is most common during spring and summer.

The fruit contains four 'seeds' (i.e. mericarps or nutlets) enclosed in the old flower 'calyx', which has ten backwards-curved (i.e. recurved) teeth or spines. These 'seeds' (1-2.5 mm long) are brown or black in colour, egg-shaped (i.e. ovoid) or pear-shaped (i.e. pyriform), and have a slightly rough surface texture.

Reproduction and Dispersal

This species reproduces by seeds that are often spread inside the 'burr-like' fruit.

These fruit readily attach to animals, vehicles, and clothing and are also dispersed in water and contaminated agricultural produce.

Environmental Impact

Horehound (Marrubium vulgare) is regarded as an environmental weed in Victoria, South Australia, the ACT and Tasmania. While it is mainly a weed of agricultural areas, it also invades native vegetation. This species is actively managed by community groups in the ACT and was recently listed as a priority environmental weed in at least one Natural Resource Management region.

Legislation

This species is declared under legislation in the following states and territories:

Management

For information on the management of this species see the following resources:

Similar Species

Horehound (Marrubium vulgare) can be confused with stagger weed (Stachys arvensis), dead nettle (Lamium amplexicaule) and wild sage (Salvia verbenaca). These species can be distinguished by the following differences: