2, 4-D (2, 4-dichlorophenoxyacetic acid) is a synthetic auxin widely used as a herbicide to kill dicotyledonous weeds. It does not affect mature monocotyledonous plants and is used to prepare weed-free lawns . IAA (Indole-3-acetic acid) and IBA (Indole butyric acid) are natural auxins, while NAA (Naphthalene acetic acid) is another synthetic auxin generally used for rooting or preventing fruit drop, but 2, 4-D is the specific example given for destroying weeds.