Annual mercuryNo picture yet

Name: Annual mercury
( town weed )

Latin name: Mercurialis annua L.

Occurrence: An annual weed, possibly native on cultivated land and waste places. It is also a garden weed and is widespread but local in southern England. Although of local occurrence it can be troublesome on lighter soils. It is not recorded above 1,000 ft in the UK.

Annual mercury was found in 3% of conventional sugar beet crops surveyed in East Anglia in autumn 1998.

Annual mercury is rich in potassium and was was regarded as a valuable purgative.

The plant is poisonous if eaten by livestock. The seeds are the most poisonous part but are important in the diet of bullfinches.


Biology: Annual mercury flowers from July to October. The male and female flowers are found on separate plants. Plants can be found in fruit for 4 months of the year.

In the field, seed germination occurs intermittently from May to early September.

Mineral uptake at early growth stages is relatively high, an important factor in plant competition.


Persistence and Spread: Seeds can remain viable in soil for 6-7 years. Seed longevity in dry storage is generally 8-10 years but seed dry-stored for 40 years has given 1% germination.

Seeds are dispersed explosively. Fallen seeds may be carried away by ants.


Management: Normal soil cultivations should keep the weed in check.

Annual mercury seed is susceptible to soil solarization.

Updated October 2007.

Further Information / Links:

For more information on this weed
»UK farmers' case studies

« Back to Annual Broad-leaved Weeds

Comments

  1. I'm not a gardener, and have been searching to find if a particular plant is a weed or not. It would be really useful if the weed names had a small photo beside them, so that obvious non-contenders didn't have to be clicked on. It's the most comprehensive site I've found, but I've given up and I'll take a cutting to the garden centre :-)
    - C Barclay 1---1-2009

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