5. For the purpose of this Schedule—
“energy crop” means a plant crop planted after 31st December 1989 which is grown primarily for the purpose of being used as fuel or which is one of the following—
miscanthus giganteus (a perennial grass),
salix (also known as short rotation coppice willow),
populus (also known as short rotation coppice poplar);
and
“environmental quality assurance scheme” means a voluntary scheme which establishes environmental or social standards in relation to the production of biomass or matter from which a biomass is derived.