Tissue-specific expression and expression levels of lncRNAs. (A) Density plot of Shannon entropy of pre- and HC-lncRNAs, and FGS transcripts. The Shannon entropy has units of bits and ranges from zero for genes expressed in a single tissue to log2(Number of tissues) for genes expressed uniformly in all tissues considered. (B) Hierarchical clustering (Ward’s method) of expression for the HC-lncRNAs and FGS genes that were expressed in at least one tissue suggests that tissue-specific expression for lncRNAs is more common than that of FGS genes. Per-gene normalization was applied to allow for visualization of relative expression in different tissues for all genes. Red indicates high expression level, blue low expression, and black intermediate expression. SAM, shoot apical meristem. (C) Density plot of maximum expression levels of pre-lncRNAs (green), HC-lncRNAs (red), and FGS (blue) across 13 distinct tissues of B73.