In ancient times the silphium plant, a form of giant fennel was highly prized:

1. from the juices of the flower came perfumes and seasonings;
2. the stalk was used as a vegetable;
3. the leaves as a garnish;
4. It had numerous medicinal qualities used in the treatment of dysentery, to cure intestinal wounds and infections;
5. an antidote to poison;
6. and finally as a form of birth control.

In fact silphium was so sought after that it was extinct by Roman times. The natural historian Pliny writes this about the plant:

. . . it takes an important place in general use and among drugs, and is sold for its weight in silver denarii. It has not been found in [Cyrenaica] now for many years, because the tax-farmers who rent the pasturage strip it clean by grazing sheep on it, realizing that they make more profit in that way. Only a single stock has been found there within our memory, which was sent to the emperor Nero. If a grazing flock ever chances to come on a promising young shoot, this is detected by the indication that a sheep after eating it at once goes to sleep and a goat has a fit of sneezing.(NH xix 38-46).

Shortly after colonists arrived from the Greek island of Thera in 630 BC, they discovered the amazing silphium plant, which grew in a small upland, ecological zones surrounding the city of Cyrene. Linguistic evidence indicates that the Libyans already knew about silphion, but it was news to the Greeks. The Cyreneans therefore had a monopoly on the sale of the plant, which was eventually worth its weight in silver (the Romans deposited it in their treasury) making the Cyreneans rich.

Trade based on Silphium was of great commercial importance to Cyrene so much so that it was often used on their coinage.

There was one problem with silphium. They couldn't farm it. The Cyreneans grew everything from saffron crocuses to olive trees, but silphium wouldn't cooperate. Like the caper bush, Theophrastus noted, it would grow wild or not at all. Silphium was a royal monopoly, with strict rules about how much could be harvested each year. The rules were broken, of course -- fennel-smugglers went through But then silphium became extinct. Pliny the Elder (23-79 A.D.) wrote that in his lifetime only one stalk of genuine silphium had been found -- which was picked and sent to Nero. It's hard to pin down exactly when extinction happened, since when people couldn't get Cyrenean silphium they substituted "Syrian silphium," or asafoetida, a fennel of greater distribution. Asafoetida is known today chiefly for smelling just ghastly, unlike silphium, yet it was considered a reasonable substitute.

So how did Silphium go extinct? There are a number of theories.

Pliny says that grazing animals, sheep in particular, ate it all. Pliny maintains that the Cyreneans could make more money off sheep than off silphium

The Ancient Greek geographer Strabo maintained a similar view, theorizing that the shepherds were increasingly disgruntled Libyans who weren't getting a cut of the silphium money, and so had no reason to keep the sheep out of the silphium patch.

A third theory, suggested by historian Alfred Andrews, is that things went wrong in 74 B.C., when Rome combined the Cyrene area and Crete into a senatorial province. Senatorial provinces were administered by governors who usually served for a year, and who got no salary. Their income was whatever they could wring from the province. They could get fast cash by leasing the grazing, and lost nothing if silphium sales went down in the future. "For a period of approximately six centuries, the supply remained unimpaired under careful control," wrote Andrews. "When this policy was abandoned, the plant became extinct in about half a century."

Which ever of the theories is true the common denomonator appears to have been domestic grazing of livestock Apparently in the Cyrene area a plant known to botanists as Thapsia garganica is found which the locals call silphium, though this is probably more wishful thinking then fact.

An interesting story linked to Silphium is that it is the origin of the idealized heart shape.