Just What Kind of Flower Is This?

If you checked out my posting here about my visit to Tizer Gardens, then this is what prompted me to make the visit when I did.  I am learning that I have to relearn some of my gardening 'habits'.  And some of the flowers and trees, while familiar from pictures, are actually in my garden here.  There is lilac everywhere.  Peonies bloom.  The sweet peas are taking over our front walkway.  But then there is this.....

At first, about 2 months ago, I thought with the fuzzy green leaves, it might be comfrey.  But it quickly outgrew that stage.  Leaf upon leaf unfurled and the stem grew taller.  Then one day it is about 3 feet tall and opened up to show this.

The brown "stuff" is very straw like in texture and over a pod of some sort.  So I cut one and took it with me to Tizer Gardens to see if they knew what it was.  I have stumped them - momentarily, I am sure.

So today I walk out and see it 'blooming'.

This has to be some sort of thistle or in the thistle family.  But there are so prickles on the stem or leaves like a thistle normally has.  But it is different and actually quite stunning.  So this is my mystery flower and my reason for my visit to the gardens.  I'm keeping my eye on it to see what happens next.

Update:  I found out what it is.  On one hand it is lovely and unusual.  On the other, it is toxic to horses and banned to even be imported to Washington State.

Botanical Name: Centaurea macrocephalaCommon Name: Giant knapweed, Yellow hardheadGenus: Centaurea

This clumping, robust perennial has unusual ramrod-stiff flower stems that bloom from early summer through late summer. Its fat, rusty buds open into large, deep yellow thistle flowers the size of a small fist. Easy to cut and dry for arrangements. This plant has big, coarse leaves that call for strong companions.Noteworthy characteristics: A tricky plant to work into a perennial garden because it draws a lot of attention.Care: Grow in moist soil in sun or partial shade.Propagation: Start seeds in a cold frame in spring, or divide plants in spring or fall.Problems: White mold, rust, mildews, thread blight, and Southern blight.

Since this is not my house really (just renting) and it was already here and obviously well established (and no horses nearby), I will probably leave it where it is.