Chi-square (χ²) tests of independence (at <i>p</i>≥0.05 level) on number of nucleotide substitutions observed in fresh and herbarium DNA.

aTotal numbers of adenine, thymine, cytosine and guanine in the dataset. bNumbers of observed substitutions and their percentages of total nucleotides observed (in brackets). cThe numbers of observed substitutions were corrected for differences in total sequence data (nucleotides) between fresh and herbarium data. Separate analyses were performed for plastid, mitochondrial, and nuclear DNA. Observed numbers in the fresh tissue data were used as expected numbers in χ2-tests.