The mustard seed symbolizes something very small and insignificant that experiences enormous growth. The parable is all about KINGDOM GROWTH. The mustard seed produces a large plant, not actually a tree, and yet large enough for birds to sit in its branches. The elements of the parable include a man who sows the seed and in this case, it is Jesus Christ sowing the seed of the Gospel. The field is the world, though the Kingdom includes the universe and Heaven. The seed is the Word of God, the message of the King. The growth speaks of the advancement of the kingdom and is witnessed today in terms of the growth of the church. The birds represent the presence of evil, satanic interference in the Kingdom.