Theophylact of Ohrid
Catena Aurea · Markusevangelium 4
And he said, Whereunto shall we liken the kingdom of God? or with what comparison shall we compare it? It is like a grain of mustard seed, which, when it is sown in the earth, is less than all the seeds that be in the earth: But when it is sown, it groweth up, and becometh greater than all herbs, and shooteth out great branches; so that the fowls of the air may lodge under the shadow of it. And with many such parables spake he the word unto them, as they were able to hear it. But without a parable spake he not unto them: and when they were alone, he expounded all things to his disciples.
Again, it put forth great boughs, for the Apostles were divided off as the boughs of a tree, some to Rome, some to India, some to other parts of the world.