just came across this while doing research on weeds.
This is known to me as wild snapdragon. Called toadflax or Linaria vulgaris. It is a perennial, reproducing by seeds and by extensively creeping roots which produce new shoots and form very dense patches.
I do hope you did not bring this pretty flower home and plant it in your garden??? Once this establishes it runs several feet before it rears the next plant. It is persistent and somewhat difficult to eradicate once you let it go.
Pretty to look at but best left in wild spaces.

lostmermaid - I came across this post in my search for how to get rid of wild snapdragons. SOMEHOW they have made their way into my flowerbed and I can confirm what you say - they are extremely difficult to get rid of.

Any suggestions for me? We've been trying to get rid of it for a few years. Have tried roundup, pulling back the mulch and pulling out the roots, etc. They seem to keep popping up anyways. I'm to the point of trying the black garbage bag over that part of the bed this year to try and keep it from spreading farther... :o(

HELP!?!?!?

Cindy

Try a pre-emergent. Round-up only kills the plant it covers, and it needs sunshine, so if the snapdragons are shaded, round-up is less effective. It's also not very effective in cold weather.

There might just be some old seeds sitting around. The
But if you do go the plastic route, get a landscape grade that can handle a little abuse. It will kill the nutrients in the soil so I'd advise against it, and the seeds can probably outlast the plastic. Maybe layered newspaper under a bark mulch might help.

From the Minisota Dept of Agriculture "For existing infestations, develop a long-term, site-specific management plan. The seedbank can persist for up to 10 years so management practices must be implemented repeatedly as the infestation regenerates from the seedbank."

Here is a link that might be useful: MN Dalmatian Toadflax