This page is from the Colorado State University Extension Service website.
Leaf Features
- Leaf blade – Flattened part of the leaf
- Petiole – Leaf stalk
- Stipules – Leaf-like appendages at the base of the leaf.
Leaf Arrangement on Stems
- Alternate – Arranged in staggered fashion along stem (willow)
- Opposite – Pair of leaves arranged across from each other on stem (maple)
- Whorled – Arranged in a ring (catalpa)
- Rosette – Spiral cluster of leaves arranged at the base (or crown) (dandelion)
Leaflet Arrangement on Petiole
- Simple – Leaf blade is one continuous unit (cherry, maple, and elm)
- Compound – Several leaflets arise from the same petiole
- Pinnately compound – Leaflets arranged on both sides of a common rachis (leaf stalk), like a feather (mountain ash)
- Palmately compound – Leaflets radiate from one central point (Ohio buckeye and horse chestnut)
- Double pinnately compound – Double set of compound leaflets
