The carrot and parsley family
Apiaceae is the family of flat-topped lacy flower heads, and it is the one family where correct identification genuinely matters. It contains most of the herbs in a kitchen and several of the most dangerous plants in the northern hemisphere, and some of them look very much alike.
around 430 genera
roughly 3,700 species
Worldwide, most abundant in northern temperate regions
Everything in this guide that belongs to Apiaceae
The signature is the umbel, a flower head where every stalk springs from a single point and rises to roughly the same height, so the whole thing reads as a flat or gently domed plate. The word comes from the Latin for a sunshade, and the ribs of an umbrella are exactly the arrangement.
In most members it goes a step further into a compound umbel: each spoke ends in another small umbel of its own. Queen Anne's lace is the clearest example there is. What looks like a single lace doily is dozens of little umbels, each carrying dozens of tiny flowers, and the effect of all that division is a surface a small insect can walk across.
That is the point of the design. These are not flowers built for bees with long tongues. The nectar sits exposed on a flat platform, and the visitors are hoverflies, small beetles and wasps, which is why an umbellifer in a garden is one of the best things you can plant for beneficial insects.
Sea holly looks nothing like the rest of the family. It reads as a thistle: a stiff spiny cone in metallic blue, surrounded by a collar of spiky bracts. There is no lacy plate anywhere in sight, and most people assume it belongs with the daisies.
It does not. It is an umbellifer whose umbel has been compressed until the stalks vanish and the flowers are packed onto a cone instead of spread across a plate. Take one apart and the individual flowers are textbook Apiaceae, five tiny petals and all. The family has simply folded the plate into a cone.
It is also the best keeper here by a wide margin, ten days to a fortnight fresh and effectively forever dried, holding that metallic blue with no treatment at all. Most of the family is soft and short lived, so eryngium is worth knowing as the exception in both directions.
This family includes poison hemlock, the plant that killed Socrates, and water hemlock, which is among the most toxic plants in North America. Both carry white umbels and both have been mistaken for wild carrot or parsley by foragers, sometimes fatally. Nobody should be eating anything from this family that they have not bought.
The risk that actually reaches a florist is different and it is phototoxicity. Giant hogweed sap contains furanocoumarins, which are harmless in the dark and cause severe blistering burns when the skin is then exposed to sunlight. The reaction can take a day to appear and the marks last for months. Common rue and even wild parsnip do a milder version of the same thing.
Cultivated Queen Anne's lace and ammi are far safer than their wild relatives, but the sensible habit is gloves when processing quantity, and washing hands before going outside. Anyone who reacts to celery or parsnip is likely to react here too.
Carrot, parsnip, celery, celeriac, fennel, parsley, dill, coriander, cumin, caraway, anise and lovage are all in this family. It is one of the most important flavor families in cooking, and the reason is that its members are unusually rich in aromatic oils.
Queen Anne's lace is literally the wild carrot, the same species as the one in the ground. Pull one up and it smells exactly like a carrot, which is the single most reliable field test. The old story is that the dark floret at the center of some heads is a drop of Queen Anne's blood where she pricked her finger making the lace.
The botanical explanation is less romantic and more interesting: that dark spot mimics an insect already feeding, and a head with one attracts more visitors than a head without. The flower is advertising a crowd it does not have.