dissociation: (chemistry) the temporary or reversible process in which a molecule or ion is broken down into smaller molecules or ions
chemical process: (chemistry) any process determined by the atomic and molecular composition and structure of the substances involved
spermatophyta: seed plants; comprises the Angiospermae (or Magnoliophyta) and Gymnospermae (or Gymnospermophyta); in some classification systems Spermatophyta is coordinate with Pteridophyta (spore producing plants having vascular tissue and roots) and Bryophyta (spore producing plants lacking vascular tissue and roots)