plants in the dark

[CHSBio]

According to my biology textbook, plants do not carry on photosynthesis at
night because their stomata are closed.  How do plants in constant
darkness (as in certain months in Alaska) carry on photosynthesis then?
Do they have special adaptations to get around this?  Thanks in advance
for your reply. --Lori  (CHSBio at aol.com)