When I was playing the game I couldn't stop feeling that a hunger mechanic was cut but that they left the hunting and foraging in. I can think of no other reason for putting two plants in the middle of a cavern with no further vegetation what so ever.
Now though this would have added an extra layer of realism to the survival of Lara, I think it would have distracted too much from the action of the game. In a game where the island was the 'enemy' and you only had to worry about the surroundings and dangerous creatures I think a hunger mechanic would have worked quite well.
What do you think?