In Luke, we read:

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> The apostles said to the Lord, “Increase our faith!” And the Lord said, “If you had faith like a grain of mustard seed, you could say to this mulberry tree, ‘Be uprooted and planted in the sea,’ and it would obey you.—Luke 17:5-6 ([ESV](http://www.esvbible.org/Luke+17/))
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Given the way Jesus used the imagery of the [mustard seed](http://www.esvbible.org/search/mustard/), I assume that he always thinks of it as a symbol of something small yet full of potential. But I've [been told](https://philosophy.stackexchange.com/questions/84/does-pascals-wager-contain-any-logical-flaws-or-fallacies/98#comment9068_98):

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> There's actually a bit more to the mustard seed than size: a mustard seed is quite robust, very spicy, and of course, you can plant it and grow mustard.
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These things are true, but would it be a valid interpretation of the text to say that Jesus suggests our faith should be like a mustard seed in terms of, say, robustness?

In other words, should we think of the mustard seed metaphor as a standard trope in Jesus' teaching?