Chris,
Triffids are a non-native pest in the garden and are really invasive. They are worse than stinging nettle and spread faster than thistle. They are apparently a mutation of a minor weed that occurred sometime in the 1960's, but there are now a couple different forms as apparently the plant genetics are not too stable. I'd rather have to deal with Bermuda crabgrass than triffids. I hope you don't get them in your garden.
A picture of a sprouting triffid seed can be found here:
http://www.google.com/imgres?i...
Here's a video introduction to triffids (not for dialup users), sorry the pictures aren't so great:
http://www.youtube.com/watch?v...
nd further information about a more recent mutation of the plant (a more recent import from England):
http://www.youtube.com/watch?v...
In depth presentation is here, but takes about 11 minutes:
http://www.dailymotion.com/vid...
Saltwater is said to be an effective control, if you can apply it in time.
