Balto-Slavic gud-

 You could add Pogezania (one of the old Prussian provinces in Poland < *-gud-j-, like Pomezania from *-med-j- to your inventory of Baltic "botanical" *gud- 'thicket, wood', and I think that Gdańsk and Gdynia may ultimately belong here as well (*gud-o:n- + -išk-). 

 

Thank you for the new example.

Why not *gud-a:n- + -išk-, which is a direct parallel to a real name of village in Lithuania (Vilnius district): Gudoniškės<*gud-a:n-išk- (yes, my list was a simplified one, can you believe?). As for Gdynia, this could well may be from *gud-o:n-ia:, as Slavs often rendered (close) o: as y in borrowings, and the suffix -uon- (<o:n), including combinations -uon-ė (<o:n-ia:) is a reality in Lithuanian toponymy (up to 70 examples), but we can also consider *gud-u:n-, cf. REAL examples like Gudžiūnai (<*gud-j-u:n-) (one of them near Jurbarkas, close to former Prussian border) from my list.

 

Please note that this doesn't imply I agree with that botanical meaning of the *gud- in these examples.

 

Sergei