13:32 least of all seeds. The mustard seed is a very small seed which may, indeed, produce a large “tree,” up to ten feet high. Jesus was not speaking to botanical specialists, of course, but to ordinary people, on their level. The actual Greek allows the meaning “among the least of all seeds.”
13:32 branches thereof. In the definitive parable of the sower, the birds of the air represented those emissaries of Satan who would snatch away the good seed whenever they could (Matthew 13:4,19). Here they are seen comfortably perching in the tree which represents the growing physical aspect of the kingdom.