Complex sentence: A second use of the term refers to pollination by insects, birds, wind, or other natural mechanisms, and contrasts with cleistogamy, closed pollination, which is one of the many types of self pollination.
Split into simpler sentences: A second use of the term refers to pollination by insects, birds, wind, or other natural mechanisms. This can be contrasted with cleistogamy, closed pollination, which is one of the many types of self pollination.