Here's What The Kelp Looks Like. Win Flinton and Dick Munroe of Rockland, employees at the Algin Corporation's plant show the two forms of kelp which grow along the Maine coast and are suitable for processing, Flinton on the left shows the horsetail variety which grows on offshore reefs and ledges while Munroe holds up a nice specimen of the broadleaf variety. stems ranging from 10 to 50 feet long are brought in and used along with the leaves. The kelp is about 95 per cent water.