March 2001. This post is an example of the dangers that exist due to the presence of weeds in commercial packets of seed. In this case, Lepidium ruderale L, stinking pepperweed, narrow leaved pepperwort, pepper grass, roadside pepperweed, fetid peppergrass, pihakrassi and passerage des décombres.
The mesage is given un-edited from the Plant Profiler, Weed Science Group, Department of Agriculture, Western Australia.
“This annual biennial herb has been found in a seed mix produced by Yates seeds. It is marketed as ‘Festival of Flowers’ and also used in another seed mix called ‘Trailing Mix’. While not illegal to import this species (unmixed), I was not slow in assessing it, once I saw the name on the list, ‘ruderale’; that almost begs to be translated as weed! The weed references I had on hand included:
Hanf M (1983) The Arable Weeds of Europe, with their seedlings and seeds. BASF Aktiengesellschaft, D-6700 Ludwigshafen Germany.
Andersen RN (1968) Germination and Establishment of Weeds for Experimental Purposes. Weed Science Society of America Handbook WSSA Illinois.
Campbell Faith T American Lands Alliance. Draft lists of exotic plant species invasive in continental United States mentioned as invasive by someone, but lacking sufficient source to include on main list.
Häfliger E, Brun-Hool J (1968) Ciba-Geigy Weed Tables. CIBA-GEIGY Ltd., Agrochemicals Division Basel, Switzerland.
Williams G, Hunyadi K (1987) Dictionary of Weeds of Eastern Europe: Their common names and importance in Latin, Albanian, Bulgarian, Czech, German, English, Greek, Hungarian, Polish, Romanian, Russian, Serbo-Croat and Slovak. Elsevier. Amsterdam.
Holm LG, Pancho JV, Herberger JP, Plucknett DL (1979) A Geographical Atlas of World Weeds. John Wiley and Sons NewYork, USA.
With a native range stretching from Western Europe to East Asia you’d think it would be satisfied, but no it’s also naturalised in Japan, New Zealand, the USA and some South American countries, including Brazil and is probably on its way to Australia now thanks to the innnovation of including this species in commercial seed mixes.
Put through the WRA spreadsheet this herb scores a 16 with little effort. I’ve since added this plant to our quarantine species list and the consignment of seed mixes (which also contained other quarantine species) has been turned back.
If you are concerned about this weed getting a foot in your state contact Yates and ask that they withdraw it from their stock lists. The states I would most likely expect it to become are problem in are southern Victoria, the high country in NSW and Tasmania.
Coincidentally, I have just been on the phone to Paul Champion in New Zealand and he mentioned that this plant is much more prevalent on the South Island while its cousin L bonariense is more prevalent on the North Island. Interestingly, Flora Europaea states “Throughout most of Europe but perhaps native only in the south”. If this plant has been widely sold already I guess we have yet another sleeper weed in the wings.”