European snapdragon?

[Gene Mirro]

They grow 70cm tall, are perennial, and spread underground.  Any ideas?

[Diane Clement]

Looks like Linaria vulgaris

[Gene Mirro]

Oh great.  Are SRGC members allowed to grow plants named vulgaris?  Somebody else suggested that it might be Linaria genistifolia.  It seems too yellow for vulgaris.  Both of them are invasive in the western US. 

[Carlo]

I don't think it's vulgaris. Try L. genistifolia or L. dalmatica.

[Lori S.]

Definitely not Linaria vulgaris which has linear leaves and is invasive... however, the spreading underground of this other species is still worrisome.

[Gene Mirro]

L. dalmatica looks right.  They are all invasive.  But the worst part is that the only way to get rid of it is to dig out all of the root.  http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/dalmatian-toadflax.aspx 

[arillady]

Pity about its invasiveness as it looks like a nice bright plant to grow.

[Gene Mirro]

It's a beautiful plant, completely trouble-free in my garden.  But it can't be killed with Roundup.  It sounds like trouble.

[Alan_b]

http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/dalmatian-toadflax.aspx.

Thats http://www.kingcounty.gov/environment/animalsAndPlants/noxious-weeds/weed-identification/dalmatian-toadflax.aspx (no full stop at the end).

[Maggi Young]

Just a comment - I'd hate to think that any plant with vulgaris in its name would be considered undesirable - that would deprive us of the utterly charming Primula vulgaris for a start....
 

[Lesley Cox]

Does vulgaris not mean "common?" Common as in lots of it, rather than in vulgar. Imagine life without Pulsatilla vulgaris, or the primrose, as you say Maggi.