This is Week Twenty Three of Giford's Bible Study Programme.
And seeing a fig tree afar off having leaves, he came, if haply he might find any thing thereon: and when he came to it, he found nothing but leaves; for the time of figs was not yet. And Jesus answered and said unto it, No man eat fruit of thee hereafter for ever. And his disciples heard it.
- Mark 11:13-14 (parallel: Matt 21:18-19)
This is another example of Jesus' bad temper. He's a bit peckish, as semi-divine beings are wont to be, and sees a fig tree. Sadly, it's not fig season, so there are no figs. In a burst of temper, Jesus curses the fig tree.
Jesus offers an interpretation at Matt 21:20-22 (and the synoptic parallel at Mark 11:20-25), but this only creates more problems. For a start, there is a contradiction here (in Matthew the tree dies at once, and the disciples marvel at this, but in Mark there is an interlude where Jesus evicts the moneychangers from the Temple; (part of) a day and a night pass before anyone notices the fig tree has withered). On top of that, Jesus' interpretation ("If ye have faith, and doubt not, ye shall not only do this which is done to the fig tree, but also if ye shall say unto this mountain, 'Be thou removed, and be thou cast into the sea', it shall be done.") is - let us say - not entirely supported by the evidence.
One to remember next time someone asks you WWJD?