Their flower or whatever is produced by the flower, (capsule, legumes, spikes, end of fuzz) all seeds originate from a flower. if they don't reproduce by seed then its a tuber root or bulb. weeds can also spread from rhizomes (horizontal branching, usually underground)
this is one of those stupid school questions that even the teacher doesn't know why it's true so they shouldn't be using it. It is because little is being used as adverb. it is only correct in the context of what you were learning at school no one would ever use it that way cuz it sounds dumb...