Fossil wood

Over time the wood will usually be the part of a plant that is best preserved (and most easily found).

This will usually include "xylon" and a term indicating its presumed (not necessarily certain) affinity, such as Araucarioxylon (wood similar to that of extant Araucaria or some related genus like Agathis or Wollemia), Palmoxylon (wood similar to that of modern Arecaeae), or Castanoxylon (wood similar to that of modern chinkapin or chestnut tree).

[3] All organic materials are replaced with minerals while maintaining the original structure of the wood.

[5] They are formed when trees are buried rapidly in dry cold or hot environments.

They are valued in paleobotany because they retain original cells and tissues capable of being examined with the same techniques used with extant plants in dendrology.