The Parsley Family includes some wonderful edible plants like the carrot and parsnip, plus more aromatic spices found in your spice cabinet, such as anise, celery, chervil, coriander, caraway, cumin, dill, fennel and of course, parsley. But unlike the Mustard or Mint families, the Parsleys are not all safe for picking and eating. In fact, the Parsley family is among the most important families of plants to learn, since it includes the deadliest plants in North America: poison hemlock and water hemlock. Note that the hemlock tree is totally unrelated.
For identification, the most distinctive pattern of the Parsley family is the "compound umbels". Notice how all the stems of the flower cluster radiate from a single point at the end of the stalk, kind of like an umbrella. At the end of each of these flower stems there is another umbrella of even smaller stems, hence the "compound umbrella" or "compound umbel". To be a true umbel, the stems or spokes must all radiate from exactly the same point. Other flowers like the common yarrow may appear to have compound umbels, but look closer and you will see that the flower stems are staggered off the main stalk, so the yarrow is not a member of this family. Another pattern of the Parsley family is that the stems are usually, but not always hollow. Kids have been poisoned using hemlock stems for straws.
When you recognize the compound umbels of the Parsley family then you know you have to be careful. You must be 100% certain of what these plants are before you harvest them for food or medicine. More than that, you must be right! People die just about every year thinking they have discovered some kind of wild carrot.
So how do you distinguish the poisonous members of the family? Don't rush it. You might think that learning plants is just a matter of filling up the disk space in your head with data, but there is a bit more to it than that. No matter what you study, whether it is plant identification, art, or math, you learn by connecting neurons in the brain to build a neural network for processing the information. Getting started is the most dangerous time, because all the plants tend to look alike– kind of green mostly. Just practice pointing out compound umbels everywhere you go, starting with the dill or fennel in the garden. The more you practice this and other family patterns, the more you will learn to see just how unique and different each plant is.
When you are proficient at recognizing the major plant families, then go back and start studying more of the individual plants. Even then, avoid rushing to conclusions. Keep in mind that when your goal is to find an answer, then you will find one, whether it is right or not.
If you are positive that you have identified a member of the Parsley family correctly, that's good. Now wait and see if you are still sure of your answer in a few days or a week. When you get good at recognizing certain species every time you see them, then you might consider trying out their appropriate edible or medicinal uses. Worldwide there are about 300 genera in the Parsley family, representing more than 3000 species. About 75 genera are native to North America.