Background:

Foliar micromorphological analysis has proven recurrently to be a valuable tool for assessing relationships at different taxonomical levels in the Quercus genus. However, Quercus is characterized by complicated taxonomic patterns resulting from frequent convergent evolution of vegetative characters, low differentiation among closely related species, and hybridization. These problems may be compounded by purely qualitative approaches to documenting the micromorphological intraspecific and interspecific variation.

Question:

Which combinations of micromorphological traits can distinguish between the different genomic lineages within the Quercus laeta complex?

Studied species:

Quercus laeta

Study site and dates:

Mexico

Methods:

We used scanning electron microscopy to qualitatively and quantitatively analyze trichomes and foliar waxes in 70 individuals from six previously identified lineages within the Quercus laeta complex. Our goal was to assess the taxonomic value of these micromorphological traits and to provide morphological support for the potential species status of these lineages.

Results:

Our results indicate that the presence or absence of stellate trichomes, the number of both glandular and non-glandular trichomes, the number of arms, and the arm length of trichomes are key features for discriminating among lineages.

Conclusions:

Our findings provided useful information to correctly identify and discriminate among genomic lineages of the Quercus laeta complex by highlighting quantitative (continuous) differences, contrary to the mostly qualitative (categorical) differences that have historically been used to discriminate among Mexican oak species.

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