About Stemma
Stemma is a strain-lineage catalog: where a cannabis variety came from, when it emerged, and who says so.
What this is
Each strain gets one card. A card records the parents, the rough date and place it emerged, the breeder where there is one, and a source for every claim. Cards link to their parents and their children, so you can walk a family back toward the landraces it came from.
The catalog aims to be honest rather than exhaustive. “Unknown” is a valid answer, dates are often decade-precision, and a strain we have not researched yet shows up as a stub so a lineage can still end somewhere. Everything is written in our own words.
The four evidence tiers
Every claim carries a badge naming the strongest kind of evidence behind it. Strongest first:
- genetically tested
- DNA evidence, such as a genotype report. Important caveat: a genetic test verifies the sample that was tested, not the name that sample was sold under. Two packs bought under the same name can be different plants, and a test on one of them says nothing about the other. Where we know it, the card notes which sample was tested.
- documented
- Contemporaneous or published records: books, magazines, interviews, seed catalogs.
- breeder claimed
- The breeder’s own account of what they crossed. Often the only account there is, and not independent.
- folklore
- Community lore with nothing stronger behind it. Worth recording, and labeled as such.
Why indica and sativa are traditional labels
Cards show a traditional label — indica, sativa, hybrid, or unknown — because that is how these plants have been described in catalogs, shops, and grower lore for decades. It is a label from that history, not a measurement.
Decades of crossing mean almost everything in circulation is a hybrid, and the label tracks how a variety has been marketed and described far better than it tracks what is in the plant. Treat it as a piece of a strain’s story, not as a prediction of how it grows or how it will feel.
How to read disputes
When credible accounts disagree about a strain’s parents, the card records the disagreement instead of picking a winner. The Lineage section shows the best-supported account. A Disputed block below it lists each competing claim, the parents it names, and its own evidence tier.
A dispute is not a flaw in the card. It is usually the most interesting thing on it.
Not medical advice
Stemma is a history and reference project for adults 21 and over. Nothing here is medical advice, and nothing here is a claim about what a strain will do for you. Talk to a clinician about anything health-related, and follow the law where you live.