where takes gimp fonts?

I have some problem with the gimp portable. I wanted work on some picture and add some little bit special font. This font I have previously installed on the host PC, normal apps like winword etc offered it for use.

Only gimp portable could not find the particular font. Furthermore I have noticed it offers only part of the fonts installed on the host machine.

Where does the gimp portable loads the fonts it is using from? Is there any restriction on what fonts it is using?