Stems modified into flat green organs performing the functions of leaves are known as

The aerial stems or branches with many internodes modified as green, fl at organs to perform photosynthetic functions like leaf, are called phylloclades, as seen in Opuntia. 
(2) Scales are highly reduced, achlorophyllous leaves seen in underground modified stems and some plants with phylloclades, as in Casuarina. 
(3) Cladodes are aerial green branches with one or few internodes meant for photosynthesis. Example: Asparagus.
(4) Phyllodes are part of leaf, other than lamina, modified as green photosynthetic structures. Example:
Petiole of Australian acacia is modified as phyllode.