move lines between word and pattern to end of file

I need to find all lines between one initial word [alter] and ending with ; to the end of the file, like this:

******some text *******
alter field with roses;
******some text *******
alter field with my text
      and flowers;
******some text *******

what I need

******some text *******
******some text *******
******some text *******
alter field with roses;
alter field with my text
      and flowers;

Can someone help me please?