Pleeeeeeeease tell me what this is! Please!

[Glutton4...]

I wonder if anyone here can help? I have been trying to find out what this plant is for three years or more. I have asked on here before, and looked in books and on most plant identification websites. Quite frankly it's driving me nuts!

Pictures to follow.

It is a herbaceous perennial, growing to around three feet tall, and flowers from mid/late June for a couple of weeks.

The flowers are daisy-like, with blunt petals, and grow in a cluster at the top of each stem. They grow in a group rather like they do on an Elder or Cow parsley.

The leaves are soft to the touch, growing in a ferny mound before the stems grow up, then they and grow individually around the stems, up the whole stem. The flower heads dry on the stem, and the stems dry-out and hollow, becoming brittle.

It transplants, and establishes easily, and is quite tough, seemingly needing little water. It appears to tolerate sun or part shade, and spreads happily. I would guess it could be mildly invasive in cases.

Heeeeelp!

[Glutton4...]

This is a view of the stems and leaves.

[Glutton4...]

This is the underside of the flower head cluster.

[Glutton4...]

This is the flower cluster.

[Thelma Sanders]

I think it's Ammi Majus

[Glutton4...]

These are pictures of young plants, which are around six to eight inches high, and were taken in the spring.

[Glutton4...]

I think it's Ammi Majus

Nope! But thank you.

[veggiechicken]

Looks like Achillea millefolium.

[Thelma Sanders]

is it pimpinella major

[Glutton4...]

Achillea grandiflora!! YIPPPPPPEEEEEEEEEEEEEEEE

Thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you, thank you!

[bearded bloke]

I think G4 is somewhat happy

[Scarlet]

Looks like Achillea millefolium.

Yes, I've got that in my garden! I think it stinks...

[veggiechicken]

Maybe G4's A. Grandiflora is a bit more refined than our common yarrow

[Glutton4...]

Luckily the ruddy thing isn't mine! Stinky, too big, and resilient to my attempts to restrict in size. Even my Customer's free-ranging chickens haven't been able to massacre it - unlike many of her other plants.

However, it is proving useful in filling a cold windy gap, where other plants have died. Also, the dried stems are useful for making teepees over newly-planted things, to keep the ruddy chickens at bay!

[1Bee]

*round of applause*