Strain hunter: the job of hunting cannabis landraces

A strain is a variety in the commercial sense, and a hunter goes looking for it. The term caught on with Strain Hunters, a documentary series produced by a Dutch seed company that filmed its own expeditions. The image of adventure it spread hides slower work.

In the field, the strain hunter meets local growers, records growing conditions and climate, observes the plants in flower and collects seeds. Back home, they sow them, select the most stable plants and keep part of the batch. Some then cross these lines with existing varieties. Others only try to keep them intact.

The job remains marginal. It is done by a small number of breeders, often linked to seed companies, and by researchers working for genetic resource collections.

A landrace is a traditional population specific to one region, shaped by growers' selection over centuries. It contrasts with the modern strain, the product of directed crosses. The distinction matters: a landrace is not a wild plant, it is a cultivated plant that stayed local.

The most cited classification comes from two botanists, John McPartland and Ernest Small. In a study published in 2020 in PhytoKeys, they examined about 1,100 herbarium specimens held in 15 herbaria. They distinguish two broad types of drug cannabis: the "Sativa" type, from South Asia (India), and the "Indica" type, from Central Asia (Afghanistan, Pakistan, Turkestan). Our article on indica and sativa explains why these words took on a very different commercial meaning.

Several famous varieties descend from landraces. Haze, for example, was put together from populations from Mexico, Colombia, South India and Thailand: our article on the Haze family traces its history.

The problem has a name: introgression, meaning foreign genes entering a local population. McPartland and Small write that the landraces of Central and South Asia are threatened with extinction through hybridisation. They give a precise example: by around 1980, Afghan landraces had been brought into southern Kashmir, and escaped plants were growing near the crops. Their conclusion is blunt: collecting and conserving these populations in their regions of origin is urgent, and banking their seeds is an immediate priority.

Genetics confirms the value of this reservoir. An international team, led in part from the University of Lausanne, sequenced the full genome of 110 cannabis plants from around the world, in a study published in 2021 in Science Advances. According to its results, cannabis was domesticated in East Asia in the early Neolithic. All current varieties, fibre and drug types alike, come from an ancient gene pool now represented by feral plants and landraces in China. Our article on the history of hemp in Europe takes over for the recent period.

Seeds hold a special place in international law. Article 1 of the Single Convention on Narcotic Drugs of 1961 defines cannabis as the flowering or fruiting tops of the plant, "excluding the seeds". That exclusion does not make transport free: each country sets its own rules on exporting seeds, which are often restrictive.

Biodiversity law adds another layer. The Nagoya Protocol, adopted on 29 October 2010, sets a simple principle: whoever uses a genetic resource must obtain the prior consent of the country where it is found, and negotiate terms of use with it, including benefit sharing. A landrace collected without that agreement is therefore a legal problem, even when the seed itself is not a narcotic.

In France, sowing is a different act. The decree of 30 December 2021 only allows Cannabis sativa L. varieties listed in the EU common catalogue or the French official catalogue, with no more than 0.30% Δ⁹-THC. It reserves the cultivation of flowers and leaves for active farmers, using certified seed. A landrace brought back from a trip meets none of these conditions. Our article on CBD seeds sets out what an individual can buy, and what they cannot sow.

The CBD hemp grown in France does not come directly from imported landraces. It relies on catalogue-listed varieties, selected for a stable composition and controlled THC. The European Commission counted 116 hemp varieties in the common catalogue in 2024. Our guide to the EU variety catalogue explains how to consult it.

The link with landraces is indirect. Breeding programmes draw on the available genetic diversity, and the collections kept in seed banks are part of it. The Lausanne study also found that selection for fibre or for psychoactive effect switched off some cannabinoid synthesis genes: each direction left part of the original heritage behind.

On a label, a variety name often keeps the trace of an origin. Durban is a city in South Africa, and Afghanistan is among the homelands of the Indica type. Our Durban Poison flower and our Afghan resin are nonetheless hemp products with no more than 0.30% Δ⁹-THC, not the original populations. The name tells a story; only an analysis tells you what a batch contains. Our guide to the certificate of analysis explains how to read one, and all our CBD flowers show their Δ⁹-THC ceiling.