Wild Carrot is TOXIC. It contains furocoumarins which absorb UV radiation upon exposure of the skin to sunlight and become photoactive and can then cause cell damage (severe blistering, eye lesions). Wild Carrot is easily mistaken for Cow Parsley (Anthriscus sylvestris) which is sometimes also called Queen Anne's Lace and it may also be mistaken for Poison Hemlock, which is also an extremely toxic plant.
The stems of Wild Carrot are hairy and have no spots on them, unlike the mature Hemlock which have red/purple spots on the stems. Wild Carrot bears a flat umbel flower head, containing hundreds of white florets, but very often with one purple floret near the centre of the umbel, and standing taller than the others. The whole plant -- but especially the root -- smells like carrots. It grows 3' tall and the flowers are borne in mid- to late summer.