1Foliage in the form of 'cladodes' or flattened shoots
1'Foliage of individual leaves.
2Foliage in the form of scales, needles, or linear leaves less than 2 mm wide.
2'Foliage in the form of broad flat leaves more than 2 mm wide.
3Foliage not dimorphic.
3'Foliage dimorphic, leaves of ultimate branchlets longer and narrower than on main shoots may be bilaterally flattened
4Leaves not bilaterally flattened
4'Leaves bilaterally flattened
5Leaves bilaterally flattened
5'Leaves bifacially flattened.
6Leaves with a groove over the midvein, (spirally placed,) lacking hypoderm, with a sweet taste
6'Leaves flat or with a ridge over the midvein, with hypoderm, without a sweet taste.
7Leaves opposite, many with multiveined leaves
7'Leaves spirally placed, uninerved