About 'Adobe Flash plugin' in software center

In software center I find I do not install 'flash plugin'. But I still can see flash in firefox. What is the matter ?

Thanks

There are two packages for installing flashplugin. The packages are called flashplugin-installer and adobe-flashplugin. adobe-flashplugin package is present in Partner Repository which is not enabled by default. While flashplugin-installer is present in multiverse repository but uses partner repository to download the source from package adobe-flashplugin as a post-install hook. If you installed ubuntu-restricted-addons metapackage. This package recommend flashplugin-installer and install it which may be your case.

More on available repositories and how to enable them.

May be you have selected installation of restricted software during OS installation