Two thousand years ago, someone in a quiet Roman frontier village carefully packed a bone full of potent, mind-bending seeds — and sealed it for safekeeping. Archaeologists have opened it, and it has them puzzled.

This narcotic plant found in a hollowed bone is now casting new light on the Roman civilization. Black henbane (Hyoscyamus niger) is a well known plant to biologists. It grows in Europe and Asia and is related to tobacco and the extremely toxic nightshade. Given its relatives, it’s not surprising then that black henbane can be used both as a narcotic and as a psychoactive substance.

Archaeologists are also quite familiar with the substance as they’ve been finding it at all sorts of sites, including Roman sites. It’s a tantalizing find: on one hand, you really want to infer that the Romans were using this plant for its properties, but the plant also grows naturally in the area. So it’s also plausible that the seeds could have just spread naturally. Now, however, conclusive evidence has been found: a stash of seeds hidden in a hollowed bone.

“Since the plant can grow naturally in and around settlements, its seeds can end up in archaeological sites naturally, without intervention by humans,” says lead author of the research, Dr Maaike Groot from the Freie Universität Berlin. “This is why it is usually classed among wild plants/weeds in archaeobotanical studies.”

Groot and colleagues were working at a rural Roman settlement called Houten-Castellum, in what is today the Netherlands. Like in other areas, they were finding all sorts of black henbane seeds. But unlike other sites, they found what is clearly a stash: a hollowed bone.

A very unusual stash

The bone container is a hollowed-out sheep or goat femur intentionally sealed at one end with a birch-bark tar plug. It contained hundreds of black henbane seeds. The chamber was about 59 mm long and 9 mm wide, large enough to hold more than a thousand seeds — and possibly up to 4,000 if completely full.

“The find is unique and provides unmistakable proof for the intentional use of black henbane seeds in the Roman Netherlands”, states Groot.

The association of black henbane with other medicinal plants in archaeological contexts further supports its intentional use. For example, at the Roman fortress hospital in Neuss, Germany, black henbane seeds were found alongside fenugreek, vervain, common centaury, common St. John’s wort, dill, and coriander. This suggests a systematic use of these plants for their therapeutic properties.

“Our study contributes to the discussion of how to distinguish between a weed naturally ending up in archaeobotanical assemblages and a plant intentionally used by people”, Groot adds. “We argue that future finds of black henbane should be studied by taking into account the context of the find and its relation to other medicinal plants.”

Bone, plants, and history

The bone cylinder, approximately 7 cm (3 in) in length, was intentionally worked at both ends and sealed with a plug of birch-bark tar. The seeds inside were identified as black henbane, and the container likely held over 1,000 seeds originally. The analysis of the plug revealed the presence of birch-bark tar, a material used since the Middle Palaeolithic for crafting tools and sealing pottery.

The bone container was discovered in a water pit dated to AD 70–100, alongside a partial cow skeleton and fragments of a quern stone. Archaeologists believe these objects are a part of an abandonment offering — a ritual deposit of objects or materials made when a site or structure is intentionally abandoned or decommissioned. This indicates a ritualistic element to the deposition of the black henbane seeds.

However, Classical writers such as Pliny the Elder discussed the plant’s medicinal applications, suggesting that it would have been used medicinally rather than recreationally in the Roman world. It’s not clear if this included a ritualistic component or if the two uses were separate. However, it’s striking that such Roman practices described in today’s Italy were spread all the way to the rural communities at the Roman Empire’s periphery.

We still don’t know exactly why and how the plant was used — but, at the very least, we know that it was used. The Houten-Castellum discovery is a testament to the complex relationship between humans and plants and the ways in which ancient societies harnessed natural resources for a variety of purposes. Black henbane, nowadays often dismissed as a common weed, can reveal much about the medical and ritual practices of ancient cultures.

“Black henbane presents problems for archaeobotanical interpretation as it could occur naturally at most of the archaeological sites where it has been found. For this reason, it is usually grouped with wild plants. Our analyses show that the plant was used by people but unequivocal cases of intentional use are very rare. Nevertheless, we suggest that black henbane should not be disregarded as a wild plant so quickly in the future; the contexts of finds and associations with other plant species and artefacts should first be carefully considered,” the researchers conclude.

* Note: Black henbane is highly poisonous! All parts of the plant can cause severe illness or death if ingested, and even handling it with bare skin can be dangerous. Admire it from a distance, and keep children and animals well away.

The study was published in the journal Antiquity.

This article was originally published in June 6, 2024, and has been edited to add more information.