Root chervil is a biennial plant, forming a storage root in the first year and then going to seed in the second year. Plants grow to about four feet (1.2 m) tall and the structure will be familiar to anyone who has seen carrots or parsnips in flower.
The root is fairly small, typically reaching two or three inches (5 to 7.5 cm) in length and perhaps half that in width. Size probably accounts for its decline in popularity, since yields are small compared to similar plants like carrot or parsnip that have much larger roots. Nevertheless, I think that root chervil is worth growing, as it has a unique flavor. Flavor is always a subjective experience, but I find root chervil particularly difficult to describe. It is something like the flavor of a carrot, with the texture of a baking potato but a bit firmer, perhaps more like a chestnut, with an aftertaste of the herb chervil.
The roots taste best after several weeks of storage or after a freeze (if you can leave them in the ground that long). You can reproduce this effect by storing the roots for a few weeks in the vegetable crisper of your refrigerator. As with most root vegetables, it is easily prepared by boiling or roasting. It is not generally (ever?) eaten raw.
The origin of root chervil’s domestication appears to be uncertain, at least to the few authors who have addressed the subject in English. The center of domestication is probably somewhere in eastern Europe. Although root chervil is now somewhat popular in France, it was popular earlier in Germany and Austria. It may never have been more than a wild collected food though.
Root chervil was introduced to Britain in 1726 as an ornamental and grown on a large scale for a time (Hickmott 2003). It was introduced to France in 1846 and a breeding program was started in 1985 that has produced several new varieties (Peron 1990).