This sentence from a book makes sense to me semantically--I understand all the terms in it--but not syntactically.
Living plant collections are insurance policies, although maintaining the premiums is high.
I think it's correct to say "the premiums are high", but what does "maintaining the premiums is high" mean?
A little bit background: the author is arguing that we need to preserve apple cultivars, and they can only be preserved as collections of living trees, which is therefore considered "insurance policies."