Silphium was one of the many herbs used by Roman cooks. It appears in dozens of recipes but has gone extinct and its true identity is hidden. Here is a brief history of the plant and its modern substitutes.
A Cyrene didrachm (silver coin) showing a silphium plant on the reverse.
Silphium: a plant so profitable that its image ended up on coins and so precious that Julius Caesar stored a 1,500-pound cache in the government treasury. This herb was a hot commodity in the ancient world, and for good reason. Classical writers like Pliny the Elder tell that the plant and the juice of its root, called laser, were used for many diverse purposes (Natural History XXII):
Laser, a juice which distils from silphium, as we have already stated, and reckoned among the most precious gifts presented to us by Nature, is made use of in numerous medicinal preparations.
According to Pliny, silphium was a cure for hemorrhoids, fevers, indigestion, and dog bites; a preservative for food; a perfume; an aphrodisiac; an early form of birth control; and any sheep that ate silphium had deliciously tender meat, in addition to being prepared in food itself. Really, the list of applications of silphium goes on
As much as silphium seems to have been used, ancient authors describe the plant to be extremely difficult to get a hold of. First of all, from what I found, Herodotus notes that silphium grew natively in a very small area in Libya, only about 125 miles by 35 miles, around the city of Cyrene (The Histories IV). The herb could not be found anywhere else, making the kings of Cyrene rulers the wealthiest in Africa.
Okay, you might think, if the Romans wanted silphium so badly, couldn’t they just plant it in other places? That thought was one that crossed the minds of many Greeks and Romans, who tried taking seeds back from Cyrenaica to plant in their own gardens. Despite their best efforts, it seemed impossible to grow silphium in captivity. Seeds either wouldn’t germinate or, if they did, the offspring would be infertile after a generation or two (modern science still can’t explain why this was).
Because silphium was so finicky, it fetched high prices across the Mediterranean. This stubbornness also led to the plant’s commercial demise: in the end, silphium yields couldn’t keep up with the Roman lust for the herb and all its spectacular uses, driving it to extinction.
In cooking, this poses a bit of a problem, considering that silphium is no more. Today, asafoetida (Ferula foetida), a sweaty-foot-smelling spice to which silphium is closely related, works as a great substitute. After the herb’s extinction, even later Roman cooks made this swap.
I can’t promise that asafoetida will work as an aphrodisiac or will cure any or all ailments, but in the kitchen, it makes a pretty good replacement. It can probably be found at your local supermarket or at an Asian food store, where you might find it’s called “hing.” If you’re having trouble finding asafoetida, I’ve read (but haven’t tried myself) that leeks or garlic work fine. I actually don’t have any asafoetida on hand at the time I’m writing this, so if I run into a recipe that calls for silphium or laser soon, I may try either one of those options.