what is this plant?

Question

It is about 4ft tall, its leaves are 30cm long and linear with spines along the centre ridge on the back of the leaf and they are in pairs all the way up the stem.. The edges of the leaves are serrated,it has a flower coming at the top of it's single stem but I can't tell what colour it is yet. they spent the winter as rosettes of about 6 leaves almost flat on the ground ', but have really sprouted since april. I have about 10 of these growing where I scattered a packet of wild flower seeds last year but I have lost the packet.

Answer 1

Teasel - birds love em but they seed like weeds once they are in.

The flower grows like a large cone shape then sprouts tiny little lilac, mauve blooms all around it.

http://www.ppws.vt.edu/scott/weed_id/diwsi.htm

Also common in the UK

Answer 2

It is probably a weed. Kinda sounds like thistle. Here is a pic of Thistle.
http://alfalfa.okstate.edu/images/weeds/composite/bullthistle-09.htm
It's just my best guess. Without a pic from you it is impossible to tell.

Answer 3

It could be a milk thistle if it is green:
http://commons.wikimedia.org/wiki/Silybum_marianum

or a mullein if it is greyish green:
http://en.wikipedia.org/wiki/Common_mullein

Answer 4

sounds to me like Japanese knotweed, they take over everything.River banks etc are like jungles. there is a massive govt financed effort to eradicate this noxious nuisance. If the stalks are a bit pinky, get expert advice immediately. Your whole neighbourhood will be blighted, and it is an offence, punishable by imprisonment to knowingly cultivate this horror. Its almst as bad as the obnoxious Leylandii. No joking, google it
hope it isn't what I suspect
good luck