Tylosis : Ingrowth of parenchymatous cells into xylem vessels and tracheids through pits due to enormous secondary growth.
Periderm: protective secondary tissue that develop by activity of cork cambium.
Bark: It includes pericycle, cortex,periderm and all dead cells outside to periderm.
Soft wood: Gymnospermous wood without vessels also called non porous wood.
Hard wood Angiospermous wood where vessels present also called porous wood.