Definition - What does Leaflet mean?
In plant biology, a leaflet refers to one part of a compound leaf. In other words, a compound leaf is made up of two or more leaflets, often three or five, although in some plants such as ferns, many more.
Cannabis plants have compound leaves with serrate leaflets, meaning leaflets that are notched and toothed at the edges. The distinctive look of cannabis leaflets in the plant world, given to them by the leaflets' diagnostic venation patterns, make cannabis plants easy to distinguish when compared to other plants with similar amounts and types of leaflets.
In cannabis cultivation, the first pair of leaves that shoot up from a seedling usually have a single leaflet. This number gradually increases up to a maximum of around 13 leaflets per leaf, with the average being seven to nine leaflets, depending on the strain/variety and the growing conditions.
At the top of a flowering marijuana plant, the number of leaflets drops down to a single leaflet per leaf.
Hydrolife explains Leaflet
In terms of plant growth, photosynthesis and transpiration occur exactly the same way in compound leaf plants of multiple leaflets and the simple-leafed plants. However, the compound leaves have a slight advantage over the simple leaves because the compound leaves often have much longer petioles (the green stalk part that connects a leaf to the stem of the plant).
Because of this, a plant with longer petioles, like cannabis plants, is better able to direct or place the leaf in direct sunlight, or, in the case of indoor grow rooms, artificial light sources. The greater the available surface to collect sunlight, the better able a plant is to gather sunlight and produce energy.
When looking a plants beyond cannabis plants, the leaves of clover, black locus, and walnut are all compound leaves comprised of three or more leaflets. Ferns are compound leaves made of multiple leaflets on a single stalk or leaf. Meanwhile, an aspen is an example of a simple leaf that is not comprised of multiple leaflets.