The family tendency to contain stimulating volatile oils means it is vital to get positive identification before harvesting, because those oils can be either healing or highly toxic, depending on the species.
Here are the main family characteristics:
(Note that yarrow and tansy, although they meet most of these general criteria, are in the Composite family.)
Most familiar parsley members are biennial, putting up basal leaves the first year and adding a flower stalk the second year, then setting seed before they die. This means that any plant whose root is harvested for food or medicine must be taken at the end of the first year or start of the second, when no flower is present to assist in identification.
Wild carrot’s small white root is edible and carroty-smelling, and the seeds are used in the treatment of certain urinary problems. Most wild carrot flowers (also known as Queen Anne’s lace) have a single purple or maroon floret in the very center. However, the plant resembles poison hemlock, distinguished by an unpleasant odor and purple splotches on the stem. Both plants have leaves with slender, feathery leaflets. Because you can die from eating poison hemlock, which shuts down the central nervous system and was used to kill Socrates, beginning foragers should not even consider harvesting wild carrot. (Poison hemlock is unrelated to the evergreen tree known as hemlock, whose needles can be used to make a healing tea.) Wild carrot flowers in summer, while poison hemlock flowers in spring.
The majestic and somewhat invasive wild parsnip looks like a yellow-flowering, giant-size wild carrot plant, up to five feet tall. The roots are edible, but only before flowering, at which point they become tough and stringy. The leaves, which have broad, flat, toothed leaflets, resemble those of water hemlock, a poisonous plant which kills by causing extremely painful convulsions.
Wild chervil flowers in mid-spring and has strongly invasive tendencies. It closely resembles poison hemlock, but it lacks the unpleasant smell and the purple spots on the stem. It loves roadsides, streambanks, and meadows.
Golden Alexanders blooms in patches, also in mid-spring. It is a slender little plant with yellow flowers.
Sweet cicely is a woodland plant that blooms in early spring and has an anise scent. Its roots are used as a palliative in the treatment of diabetes.
Angelica is another towering plant with greenish flowers forming a globe rather than an umbrella shape. It grows alongside streams. Preparations of its roots are employed to stimulate digestion.
For more information on plant families and how they are helpful in identification, see The Mint Family.