Sure looks like a Taraxacum officinale. The little shriveled flower might be turning into the ubiquitous pouf of fluff even now.
Thx a lot - I have searched for the name on google images and believe you are 100% right, it is taraxacum officinale
Not Taraxacum, which does not have stem and branching inflorescence. This is Sonchus sp, most likely.
It seems that you are right especially with the composition of the flower - one last question: does this plant harms other plants like climbing roses or ageratum?
No direct harm, unless it is too dense and takes too much water and food resources. Unlike the dandelion, it is less invasive and easier controlled.
