Weed Identification

Australia > > Horehound

Horehound

Marrubium vulgare

Family: Lamiaceae.

Form: Herb

Origin: Native of southern and western Europe, western and central Asia, North Africa.

Flowers/Seedhead: Petals white. Flowers all year, mostly summer and autumn.

Description: Perennial spreading herb to 80 cm high. Leaves to 7 cm long, margins with rounded teeth; hairs on leaves and stems long and star-shaped. Fruit a burr with backward facing hooks. Seeds about 2mm long, with a roughened surface. Deeply rooted with woody taproot and fibrous lateral roots.

Distinguishing features: Distinguished by flowers in dense clusters around the stem above the leaf axils; leaves grey-green, opposite, woolly and aromatic, and stems 4-angled.

Dispersal: Mostly by fruit with hooks that attach to wool, fur, bags and other material. Spread also occurs via waterways.


Leaf upper surface wrinkled & grey-green;
lower white & woolly

Notes: A hardy, widespread weed of disturbed areas. Common around sheep camps and stock yards. Unpalatable to stock and with its free seeding habit quickly spreads. Horehound is a weed throughout much of the temperate world. Horehound has been used as an ornamental and for brewing of beer. Biological control agents have been released and are showing promise, especially in higher rainfall areas.

References:

    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 496–499. Flora of NSW. G. Harden (ed), Vol. 3, 1992, pages 639–640.

Web References: Search Australian web sites for further information on this weed.

Flowers & fruit. Inset: Seedlings
photo J.R.Hosking
Complete groundcover,
McKillops Bridge, Vic, May
Seeds

This weed has been included in the WEEDeck field guide as card H15

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.

 

Australia > > Horehound

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