Silphium was a flowering plant from ancient North Africa that the Greeks and Romans prized, among other uses, as a contraceptive and abortifacient. The plant went extinct sometime during the first century CE, so no one has ever been able to test the real thing in a modern laboratory. What researchers have done, though, is study silphium’s surviving botanical relatives in the genus Ferula and found that several of them contain compounds with genuine anti-fertility effects in animal models. The question of whether silphium actually worked as birth control is more interesting than a simple yes or no, because the answer sits at a crossroads of ancient texts, modern pharmacology, and a plant that no longer exists to settle the debate.
What Was Silphium and Why Did It Matter
Silphium was a plant that grew in a narrow strip of land near Cyrene, a Greek colony on the coast of what is now eastern Libya. Ancient writers placed it in the same botanical family as fennel and giant celery, and modern scholars generally agree it belonged to the genus Ferula, a group of large, umbrella-flowered plants in the carrot family.1Journal of Experimental Botany. Botany meets archaeology: people and plants in the past It was harvested primarily for its resin, a gummy sap extracted from the stem and roots, though the seeds and leaves were also used.
Cyrene built enormous wealth on the silphium trade. The plant’s image appeared on the city’s coinage for centuries, and it was exported across the Mediterranean as both a luxury spice and a medicine.2MDPI. Searching for Silphium: An Updated Review Ancient authors described silphium as something close to a cure-all: it treated coughs, sore throats, fevers, indigestion, warts, and various aches. But the use that has captured modern imagination most is its role in reproductive medicine. Writers including Soranus of Ephesus, a second-century physician, recommended silphium juice taken orally once a month to prevent conception, or as a drink to induce menstruation and terminate early pregnancies. Pliny the Elder called it worth its weight in silver denarii.
The Ancient Claims About Contraception
The textual evidence for silphium as a contraceptive comes from several ancient medical and botanical writers, spanning roughly the fifth century BCE to the second century CE. Hippocratic texts mention silphium in gynecological contexts. Soranus, whose work on gynecology is the most detailed surviving ancient medical text on the subject, listed silphium juice among substances a woman could drink to prevent pregnancy, alongside pomegranate and other plant extracts. Dioscorides described similar uses.
These writers did not distinguish clearly between contraception and early-term abortion. What they described was often a substance taken after intercourse to prevent a pregnancy from establishing itself, closer to what modern pharmacology would call a post-coital anti-fertility agent. Silphium’s resin was the preferred form, and the doses described were small, typically a chickpea-sized lump dissolved in liquid. The specificity of the instructions, repeated across authors who were otherwise skeptical of folk remedies, has led historians to take the claims seriously rather than dismissing them as superstition.
That said, ancient medical writers also recommended substances we now know to be useless or dangerous as contraceptives. The fact that multiple authors endorsed silphium does not prove it worked. It does suggest, at minimum, a widespread and persistent cultural belief in its effectiveness, one that held up across several centuries and medical traditions.
What Modern Studies on Ferula Species Actually Show
Since silphium itself is extinct, researchers have tested its closest surviving relatives for anti-fertility activity. The results are genuinely striking. Several species in the genus Ferula have shown the ability to prevent pregnancy in laboratory animals through different mechanisms.
Ferula assafoetida, commonly known as asafoetida and still used as a cooking spice across South and Central Asia, was tested as a post-coital anti-fertility agent in female rats. An oral dose of its extract prevented pregnancy in 80% of the animals, and when the extract was prepared in a more bioavailable form, pregnancy inhibition reached 100%. Even at lower doses, the extract sharply reduced the number of embryo implantations in the uterus.3Pharmaceutical Biology. Post-Coital Antifertility Activity of Ferula Assafoetida Extract in Female Rats
Ferula jaeschkeana, another species in the genus, showed a different mechanism. When a hexane extract of its aerial parts was given orally to pregnant rats, the animals’ ovaries continued cycling as though they were not pregnant, producing new follicles and corpora lutea instead of sustaining the hormonal conditions needed for implantation. The uterine lining in treated rats appeared structurally unreceptive to embryos, and no implantation sites developed.4Journal of Ethnopharmacology. Postcoital contraceptive action in rats of a hexane extract of the aerial parts of Ferula jaeschkeana In separate work, the same species’ hexane extract also demonstrated estrogenic activity: it increased uterine weight in rats whose ovaries had been removed, confirming that the plant contains compounds capable of interacting with estrogen receptors.5Phytotherapy Research. Post‐coital contraceptive effects of Ferula jaeschkeana Vatke extracts in rats and hamsters and their hormonal properties
Ferula hermonis, a species native to the eastern Mediterranean, contains a compound called ferutinin that interacts with estrogen receptors and also mimics the activity of follicle-stimulating hormone and luteinizing hormone, two hormones central to the reproductive cycle.6PubMed. Assessment of Ferula hermonis Boiss fertility effects in immature female rats supported by quantification of ferutinin via HPLC and molecular docking Ferutinin has attracted particular interest because it has been identified in multiple Ferula species and could plausibly be the kind of bioactive compound that silphium’s resin contained.
These findings do not prove that silphium worked in humans. Rat and hamster studies are a starting point, not a conclusion. Doses were controlled in ways that ancient use never could be. But the pattern is hard to ignore: multiple species closely related to silphium contain compounds with real anti-fertility effects, working through mechanisms that are pharmacologically plausible and not just toxic side effects.
Why the Gap Between Ancient Use and Modern Proof May Never Close
The fundamental problem is that silphium is gone. Even if every Ferula species ever tested showed contraceptive activity, that would tell us about the genus, not about the specific chemistry of the specific plant that ancient Cyrenaicans harvested. Plant chemistry varies enormously between species and even between populations of the same species growing in different soils and climates. It is entirely possible that silphium had a unique cocktail of sesquiterpene coumarins, phenylpropanoids, or other bioactive compounds that its relatives do not share in the same proportions.
There is also the question of how silphium was prepared. Ancient recipes called for the resin, which concentrates certain compounds. They specified oral administration, usually dissolved in wine or water. The dose was small. Modern animal studies, by contrast, have tested crude extracts at measured doses by body weight, a far more controlled approach. Whether an ancient woman taking a lump of resin in wine would have ingested enough of the right compounds to reliably prevent pregnancy is genuinely unknown.
Historians of ancient medicine also point out that silphium was used alongside other plants in compound recipes. Soranus’s prescriptions often combined multiple ingredients. Isolating silphium’s individual contribution from these mixtures, even conceptually, is difficult. The ancient sources do single out silphium as effective on its own, but they were not running controlled trials.
How Silphium Went Extinct
The traditional explanation is straightforward: people loved silphium so much they harvested it to death. Ancient writers noted that the plant was difficult or impossible to cultivate. It grew wild in a limited geographic range and resisted transplantation. As demand soared across the Mediterranean, harvesters dug up roots and cut stems faster than the plant could reproduce. Pliny recorded that the last known stalk was reportedly sent to Emperor Nero as a curiosity.7Journal of Experimental Botany. Botany meets archaeology: people and plants in the past
Recent scholarship has complicated this picture. A 2021 study in conservation science argued that overharvesting alone probably was not sufficient to wipe out silphium. The Cyrenaican region underwent significant environmental change during the centuries of silphium’s exploitation: widespread deforestation, expansion of cropland, and accelerating desertification. These changes would have degraded and eventually eliminated the specific habitat conditions the plant needed to germinate and grow. The study concluded that anthropogenic environmental change, rather than direct over-collection, was the dominant factor, potentially making silphium the first recorded case of a human-induced, climate-related extinction.8Frontiers in Conservation Science. Reassessing the Role of Anthropogenic Climate Change in the Extinction of Silphium
Other reviewers describe both factors working together: over-exploitation compounded by local climate shifts squeezed the plant from both sides.9Research Journal of Pharmacognosy and Phytochemistry. The journey of cyrenaic medicinal plant Silphium: A review The plant’s inability to be cultivated was probably the critical vulnerability. A species that can only reproduce in wild conditions and cannot be farmed is uniquely fragile when its habitat shrinks. Had the Romans been able to grow silphium in gardens or fields the way they grew other medicinal herbs, the story might have ended differently.
The Ferula Drudeana Candidate
In recent years, a Turkish botanist drew attention to Ferula drudeana, a rare plant found in a small area of central Anatolia, as a possible surviving relative or ecotype of silphium. The plant visually resembles ancient depictions of silphium, shares its general growth habit, and produces a resin with aromatic properties.10International Journal of Gastronomy and Food Science. Ancient cuisine revisited: Aroma profiling of resin from Ferula drudeana — culinary potential and gastronomic applications of the putative silphium The proposal generated considerable media excitement and some scholarly debate.
Chemical analysis of Ferula drudeana’s roots has revealed a complex mix of sesquiterpene coumarin ethers and phenylpropanoid compounds, some of them newly described and others shared with other Ferula species.11PubMed Central. Sesquiterpene Coumarin Ethers and Phenylpropanoids from the Roots of Ferula drudeana, the Putative Anatolian Ecotype of the Silphion Plant Whether any of these compounds have contraceptive or anti-fertility properties has not yet been tested directly. The connection to silphium rests on morphological similarity, geographic plausibility, and the plant’s chemical richness, but not on any demonstrated reproductive pharmacology so far.
When Ferula drudeana’s resin was tasted alongside asafoetida in experimental recreations of ancient Roman recipes, tasters noted a subtle bitterness, a delicate floral quality, and a hint of frankincense. The differences between the two resins became less obvious in simple wine dressings, though asafoetida performed better in cooked meat dishes where heat transformed its sulfurous notes into desirable caramelized, umami flavors.12ScienceDirect (International Journal of Gastronomy and Food Science). Ancient cuisine revisited: Aroma profiling of resin from Ferula drudeana — culinary potential and gastronomic applications of the putative silphium These culinary experiments are interesting but do not address the contraceptive question. A plant can taste like descriptions of silphium without sharing the pharmacological properties that made silphium medically important.
Other Botanical Candidates
Ferula drudeana is not the only plant proposed as silphium or its relative. A long-running scholarly tradition has offered several alternatives. Ferula tingitana, a large species that still grows in modern Libya, visually resembles ancient depictions and has demonstrated effects on the menstrual cycle. Thapsia garganica, sometimes called deadly carrot, belongs to a different genus entirely but shares a strong visual resemblance to silphium and possesses pronounced pharmaceutical properties, including activity against cancer cells.13Heritage. Searching for Silphium: An Updated Review – Section: Candidate Plants—Hiding in Plain Sight?
None of these candidates has been definitively identified as silphium. The challenge is that the carrot family produces many large, resinous, umbrella-flowered plants across the Mediterranean and Near East, and the ancient descriptions, while detailed for their era, are not precise enough to make a definitive botanical identification. Coins depict a plant with a thick stem, large leaves, and a branching flower head, features that match dozens of species. Without a preserved specimen, DNA evidence, or an unambiguous ancient illustration with a modern equivalent, the identity of silphium may remain permanently unresolved.
The Heart-Shaped Seed Theory
A popular claim holds that the heart shape we use as a symbol for love and romance traces back to the shape of silphium seeds, which appear on some Cyrenaican coins in a roughly heart-like form. The idea is appealing: an ancient contraceptive plant used for love and sex becomes the origin of the universal love symbol. Some coins from Cyrene do depict seeds with a pointed tip and two rounded lobes, and the resemblance to a stylized heart is real enough.
Most historians of art and symbolism, though, consider this connection speculative at best. The heart shape has multiple proposed origins, and its widespread use as a love symbol does not appear consistently until the medieval period, over a thousand years after silphium vanished. The coins themselves are not labeled as depicting seeds specifically for romantic or sexual associations. It is a fun theory that circulates widely online, but treating it as established history overstates the evidence.
What Asafoetida Tells Us
Asafoetida, the resin of Ferula assafoetida, deserves special attention because it was silphium’s ancient replacement. When silphium became scarce and then extinct, ancient writers noted that asafoetida was used as a substitute, though they generally considered it inferior. Roman cooks called it “laser” and used it as a flavoring. It remains a staple spice in Indian cooking today.
The anti-fertility data on asafoetida are among the strongest for any Ferula species. As noted earlier, its extract prevented pregnancy in 80% of rats at standard doses and 100% at enhanced bioavailability, while lower doses still reduced implantation numbers significantly.14Pharmaceutical Biology. Post-Coital Antifertility Activity of Ferula Assafoetida Extract in Female Rats If the acknowledged substitute has this level of activity, it is at least plausible that the preferred original had comparable or greater effects. This is circumstantial reasoning, not proof, but it is the kind of indirect evidence that makes pharmacologists take the ancient claims seriously rather than filing them under myth.
Interestingly, the asafoetida study found no estrogenic activity in the extract, meaning the anti-fertility mechanism was not simply mimicking estrogen. This contrasts with Ferula jaeschkeana’s extract, which did show estrogenic effects. The implication is that different Ferula species may prevent pregnancy through different biochemical pathways, which makes the question of silphium’s specific chemistry all the more important and all the more unanswerable.
Why Silphium Still Captures Attention
The enduring fascination with silphium as a contraceptive is partly about the plant itself and partly about what it represents. If an effective herbal contraceptive existed two thousand years ago and was lost to extinction, that raises uncomfortable questions about what else humans may have destroyed before understanding its value. Conservation scientists have framed silphium’s extinction as a cautionary story: a species driven to oblivion by the intersection of market demand and environmental degradation, a pattern that would look familiar to anyone tracking modern biodiversity loss.15Frontiers in Conservation Science. Reassessing the Role of Anthropogenic Climate Change in the Extinction of Silphium
For pharmacologists, silphium is a reminder that traditional plant medicines sometimes contain genuinely active compounds, not always, and not reliably, but often enough that dismissing them outright means missing leads. The Ferula genus has yielded real anti-fertility agents in controlled studies. Whether any of them will ever produce a usable human contraceptive is a separate and much harder question, one that would require years of safety testing and dose optimization that no one is currently pursuing. For now, silphium occupies a peculiar middle ground: too well-supported by pharmacological analogy to dismiss, too thoroughly extinct to confirm.