This word for a cluster of trees or a clod of soil may come from the Dutch for "lump"
Bruce and Kim have... [DOC] [TLE] clumps - Memidex dictionary/thesaurus [PAR] Type of: sound; (meet) to come together as in a cluster or flock ... "lump, cluster of 
trees", from Middle English clompe "a lump" (about 1300), from.