Achillea cassis is red and purple?

I have a few achillea cassis plants which are all about the same shade of red except one which is mostly red but a few stems have purple flowers on them


does anyone know why this has happened?

 

Here are some pics

So other achillea cassis in the garden









Then this is the odd one

 

Not sure why but mine are the same, 3 plants grouped together all with different coloured flowers.

 

are the different colour flowers on the different plants? or the same plants

cause this is one plant with two different colours

 

Same as yours @Dips, I'll take a pic tomorrow when I get home.

 

Not sure about Achillea, in our garden they self seed and the seedlings are the old dull white colour and they tend to take over and crowd out the originals. However, in other types of plants a 'sport' may arise which is different in some way to the parent plant. Indeed many varieties now have arisen this way.
I

 

Ah thats kewl thank you :-)