Cannabis is an dioecious, flowering herb. The leaves are palmately compound or digitate, with serrate leaflets.
The first pair of leaves usually have a single leaflet, the number gradually increasing up to a maximum of about thirteen leaflets per leaf (usually
seven or nine), depending on variety and growing conditions.
At the top of a flowering plant, this number again diminishes to a single
leaflet per leaf.
The lower leaf pairs usually occur in an opposite leaf arrangement and the
upper leaf pairs in an alternate arrangement on the main stem of a mature plant.
The leaves have a peculiar and diagnostic venation pattern that enables
persons poorly familiar with the plant to distinguish a cannabis leaf from
unrelate species that have confusingly similar leaves (see illustration).
As is common in serrated leaves, each serration has a central vein extending
to its tip.
However, the serration vein originates from lower down the central vein
of the leaflet, typically opposite to the position of, not the first notch down, but the next notch.