Strain hunter: the job of hunting cannabis landraces

In the commercial sense, a strain is a variety, and a hunter is someone who goes looking for one. The term spread with Strain Hunters, a documentary series in which a Dutch seed company filmed its own expeditions. The adventure the series put on screen hides slower work.

In the field, a strain hunter meets local growers, notes the growing conditions and the climate, watches the plants in flower and collects seeds. At home, the seeds are sown, the most stable plants selected and part of the batch kept. Some hunters then cross these lines with existing varieties, while others aim only to keep them intact.

Few people do this work: a small number of breeders, often linked to seed companies, and researchers working for genetic resource collections.

A landrace is a traditional population belonging to one region, shaped over centuries by the growers who selected it. The modern strain, by contrast, comes from directed crosses. Keep in mind that a landrace was never a wild plant: it is cultivated, and it stayed local.

The classification cited most often is the work of two botanists, John McPartland and Ernest Small. For a study published in 2020 in PhytoKeys, they examined about 1,100 specimens held in 15 herbaria. They divide drug cannabis into two broad types: the "Sativa" type from South Asia (India) and the "Indica" type from Central Asia (Afghanistan, Pakistan, Turkestan). Why these words came to mean something very different in commerce is explained in our article on indica and sativa.

Several famous varieties descend from landraces. Haze was assembled from populations originating in Mexico, Colombia, South India and Thailand, a history traced in our article on the Haze family.

The process is called introgression: foreign genes entering a local population. McPartland and Small write that hybridisation threatens the landraces of Central and South Asia with extinction. Their example is precise. By around 1980, Afghan landraces had been introduced into southern Kashmir, and escaped plants were growing near the crops. The two botanists conclude bluntly that collecting and conserving these populations in their regions of origin is urgent, and that banking their seeds is an immediate priority.

Genetics shows how valuable this reservoir is. In a study published in 2021 in Science Advances, an international team partly led from the University of Lausanne sequenced the full genome of 110 cannabis plants from around the world. Its results place the domestication of cannabis in East Asia in the early Neolithic. Every current variety, fibre and drug types alike, descends from an ancient gene pool represented today by feral plants and landraces in China. For the recent period, see our article on the history of hemp in Europe.

International law treats seeds apart. 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". Transport is still regulated, because each country sets its own rules on exporting seeds, and those rules are often restrictive.

Biodiversity law adds a further layer. The Nagoya Protocol, adopted on 29 October 2010, lays down a simple principle. Anyone using a genetic resource must obtain the prior consent of the country where it is found and negotiate terms of use with that country, benefit sharing included. A landrace collected without such an agreement therefore raises a legal problem, even though the seed itself is not a narcotic.

Sowing is a separate act under French law. 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 to active farmers using certified seed. A landrace brought home from a trip meets none of these conditions. What an individual can buy, and cannot sow, is set out in our article on CBD seeds.

CBD hemp grown in France does not descend directly from imported landraces. Its varieties are listed in the catalogue and selected for a stable composition and controlled THC. The European Commission counted 116 hemp varieties in the common catalogue in 2024. How to consult it is explained in our guide to the EU variety catalogue.

Landraces come into the picture indirectly. Breeding programmes draw on whatever genetic diversity is available, including the collections kept in seed banks. The Lausanne study also found that selecting for fibre or for psychoactive effect switched off some cannabinoid synthesis genes, so each direction of selection left part of the original heritage behind.

A variety name on a label often recalls an origin. Durban is a city in South Africa, and Afghanistan is one of the homelands of the Indica type. Our Durban Poison flower and our Afghan resin are still hemp products with no more than 0.30% Δ⁹-THC, and neither is one of the original populations. A name tells a story, while only an analysis tells you what a batch contains. Our guide to the certificate of analysis explains how to read one, and every one of our CBD flowers shows its Δ⁹-THC ceiling.