What fruit is Jesus referring to in St John 15?

Jesus often used the vineyard (fruit of the vine) as an anology for the kingdom of God. Jesus Himself is described as the 'true vine' and His disciples as the 'branches.' The fruit He speaks of is another anology for someone's 'works.' That is to say one evidence of saving faith is the existence of good works in the lives of believers. Those who do the works of the devil show that they are of the devil.