nycbotanist's Identifications

Images:

1. in situ
2. Entire plant extracted, with shadow for rough scale.
3. Main root, with foot for scale.

I've been battling the spread of this in my garden. This year, I'm employing more agressive (and labor intensive) techniques.

• Locate and flag/mark the location where the stem emerges from the ground, however small the plant, even a single leaf.
• Fork to loosen soil around the base of the stem, 6-12" out.
• Carefully dig deep into the loosened soil and lever up to see if I got beneath the propagule/root. If not, remove the soil to a sieve and keep digging.
• Continue to remove and sift/sieve soil until all roots of the plant, and most of the soil around it, have been removed.
• Destroy any propagules found.
• Return the sifted soil to the same hole. DO NOT USE FOR ANYTHING ELSE.
• Restore the flag/marker to show from where it's been cleared, and to keep an eye out for reemergence.

Unfortunately, if any plant has ever set seed, even this level of intervention this is insufficient. The seeds are too small to filter with a soil sieve. There can be a seed bank that goes unobserved until seedlings emerge. I think this is how I accidentally spread it to multiple locations in my garden. That's why it's important to not use the soil anywhere else, for anything else.