Maternal Inheritance: when a trait comes from the mother only
In short
Maternal inheritance means a trait is passed to the offspring by the mother plant alone, regardless of what the father contributes. The father may carry the same trait, yet it still appears in the offspring only through the maternal line.
How you recognise it
The clean proof runs through the reciprocal cross. Swap mother and father, and if the offspring look different depending on cross direction, the trait cannot be inherited purely through the nucleus. If it always follows the mother, it is maternally inherited.
The classic case comes from Carl Correns: in the four-o’clock, the mother plant alone decided whether the offspring got green or mottled leaves, because the trait hangs on the chloroplasts.
What is maternally inherited in cannabis
In cannabis, maternal inheritance concerns the genes outside the nucleus, that is, cytoplasmic inheritance through chloroplasts and mitochondria. These organelles come at fertilisation almost entirely from the egg cell; the pollen barely contributes them.
What does not belong here
This is exactly where a common misconception sets in. Aroma and active compounds in cannabis are not maternally inherited, because their genes sit in the nucleus and therefore come from both parents. Reciprocal crosses show no consistent mother effect on cannabinoid composition. The maternal contribution is real, but small and limited to the organelles; it does not set the scent profile.