[On Pasture 13 April 2015 by Kathy Voth] Opinion — Kathy Voth asks, “Should we consider legalising weeds such as Canada thistle?" Canada thistle (cirsium arvense, also known as Creeping thistle in Europe and in Australia as California thistle) is one of my favourite pasture plants for a number of reasons: It's alfalfa-like in nutritional value. It is very resilient. It spreads via seeds and roots. It can grow in all kinds of climates, soils and precipitation levels, so it’s always there for us when we need some extra forage. It’s really easy to teach livestock to eat it. In fact, I think of Canada thistle as the “Gateway Weed.