"Note: Female Cannabis flowers and plants will be referred to as pistillate and male flowers and plants will be referred to as staminate in the remainder of this text. This convention is more accurate and makes examples of complex aberrant sexuality easier to understand.
The first sign of flowering in Cannabis is the appearance of undifferentiated flower primordia along the main stem at the nodes (intersections) of the petiole, behind the stipule (leaf spur). In the prefloral phase, the sexes of Cannabis are indistinguishable except for general trends in shape.
When the primordia first appear they are undifferentiated sexually, but soon the males can be identified by their curved claw shape, soon followed by the differentiation of round pointed flower buds having five radial segments.
The females are recognized by the enlargement of a symmetrical tubular calyx (floral sheath). They are easier to recognize at a young age than male primordia. The first female calyxes tend to lack paired pistils (pollen-catching appendages) though initial male flowers often mature and shed viable pollen. In some individuals, especially hybrids, small non-flowering limbs will form at the nodes and are often confused with male primordia.
Cultivators wait until actual flowers form to positively determine the sex of Cannabis.
The female plants tend to be shorter and have more branches than the male.
Female plants are leafy to the top with many leaves surrounding the flowers, while male plants have fewer leaves near the top with few if any leaves along the extended flowering limbs."
