Hierarchical clustering dendrogram trees for juvenile and mature wood cDNA libraries. ESTs or unigenes from each of the four libraries (juvenile earlywood-JE, juvenile latewood-JL, mature earlywood-ME and mature latewood-ML) were annotated against the UniProt and TIGR databases, and assigned with GO terms. The abundance of ESTs or unigenes in each GO term was calculated for each library, and further normalized as a percentage based on the number of ESTs or unigenes in each library. Statistical significance of EST or unigene abundance in each GO term among the four libraries was valuated by Chi Square tests and P-values. The normalized EST or unigene abundance was used to construct the hierarchical clustering dendrogram trees. A: the dendrogram tree for ESTs. B: the dendrogram tree for unigenes.