Leaf types are recorded for predominant vegetation type in a target canopy. Simple two categories of leaves are Broad-leaf and Needle-leaf. Based on seasonal changes these categories can further be sub-divided in evergreen, deciduous, semi-deciduous classes. Similarly based on morphological characteristics, leaves can be described based on single leaflet/multiple leaflet, leaf colour, texture, margins, leaf base.

Some useful information can be found here.

source: Texas A&M Forest Service