The main ribs in medieval vaulting engage with the tops of supporting columns or with the ridge rib - see tierceron vaulting. Any additional ribs, which are purely decorative, are known as lierne ribs. The resulting vault is known as lierne vaulting. Where liernes grew more numerous, and created 'star' patterns, the result was known as stellar vaults.
Local examples (click to enlarge and read captions)
Cathedral – Warrior chapel
Cathedral – Black Prince's chantry
Cathedral – south west porch
For help with terminology applied to the various
types of rib, click here