'Mustard seed' in the Bible

It is, like, unto a grain of mustard seed, which a man took and cast into his own garden; and it grew, and became a tree, and, the birds of heaven, lodged amongst its branches.

And the Lord said - If ye have faith like a grain of mustard-seed, ye should be saying unto thismulberry-tree - Be uprooted! and be planted in the sea, - and it should obey you.