Plant Sexual Expression
Interview: Understanding Sexual Expression in Cannabis Plants
Caller: Hey Aquaponic Dumme, I’ve been reading about how cannabis plants can be male or female, but I’m confused about how that actually works. Are they born that way, or does it change?
Aquaponic Dumme: Great question. In botany, there are two main types of sexual expression — phenotypical sexual expression and genetic sexual expression. When people talk about a plant’s sex, they’re usually referring to the phenotypical one — what’s visible. That’s what the cannabis community focuses on, because it’s what can be seen and handled. You can remove male organs to prevent pollination or harvest the female flowers for consumption.
Caller: So plants don’t start out male or female?
Aquaponic Dumme: Exactly. Plants start off without any sex at all. To have a sex, they need sex organs, and immature angiosperms don’t have any. They only develop sexual characteristics once they reach maturity. That’s where it gets interesting — genetics guide how they develop, but they’re not the only factor that determines sexual expression.
Caller: So genetics don’t tell the whole story?
Aquaponic Dumme: Right. You can test a plant’s genetic sexual expression using a PCR test, which maps part of the plant’s genome. For cannabis, molecular markers like MADC2 and SCAR332 are used to estimate sex identification probabilities. But remember, those are probabilities, not guarantees.
Caller: So even if the test says it’s female, it might not actually turn out that way?
Aquaponic Dumme: Exactly. Genetics are like a blueprint — they show how the plant should develop, but not necessarily how it will. Many factors influence sexual expression: epigenetics, disease, pests, environmental conditions, light, nutrient availability, stress, plant hormones like auxin, cytokinin, and gibberellins, the plant’s developmental stage, and even how close other plants are. All of these can affect how the plant expresses its sex. The actual sex is only determined once the plant matures.
Caller: That’s wild. So plants don’t have a fixed sex like humans do?
Aquaponic Dumme: Exactly. Unlike humans, which are born with defined sex organs, angiosperm plants develop their sex over time. Their sexual expression is flexible and influenced by many variables, not just chromosomes. This has been proven in numerous studies and supported by decades of research.
Caller: So there’s no way to know for sure what sex a cannabis plant will be before it flowers?
Aquaponic Dumme: That’s right — there’s no way to know with absolute certainty before flowering. But that uncertainty is actually what makes feminization possible. All dioecious plants, including cannabis, evolved from monoecious ancestors, meaning the genetic code for hermaphroditism exists in every cell.
Caller: So how do feminized seeds work then?
Aquaponic Dumme: Feminized seeds are created by controlling which genetic material gets passed to the offspring, encouraging the plant to develop more female traits. This is done by ensuring the ovule only receives maternal genetic markers, either from the same plant or another with strong feminine expression. But again, since genetics don’t fully control sexual expression, even feminized plants can sometimes develop differently than expected.
Caller: So it’s all about probabilities and influences, not absolutes?
Aquaponic Dumme: Exactly. Cannabis sex expression is a complex interaction between genetics and environment. The plant’s DNA sets the stage, but the environment and conditions decide how the performance plays out.
References:
Ma, Hong. Current Biology, Volume 9, Issue 17, R636–R639
Faux, A.M., Draye, X., Flamand, M.C., Occre, A., & Bertin, P. (2016). Identification of QTLs for sex expression in dioecious and monoecious hemp (Cannabis sativa L.). Euphytica, 209(2), 357–376
Stehlik, I., Friedman, J., & Barrett, S.C.H. (2008). Environmental influence on primary sex ratio in a dioecious plant. Proceedings of the National Academy of Sciences of the United States of America
Faux, A.M., Berhin, A., Dauguet, N., & Bertin, P. (2014). Sex chromosomes and quantitative sex expression in monoecious hemp (Cannabis sativa L.). Euphytica, 196(2), 183–197
