Micromorphological characters variation of lemma and palea in subtribe of Loliinae (Poaceae)

The subtribe Loliinae is one of the largest subtribes of Poeae with about 600 species. Festuca is a large genus with close relations to other genera as Lolium, Castellia, and Vulpia. The taxonomic history of the Festuca-Lolium species group is very complicated. The polyploidy and hybridization make it more confusing. Due to the morphological similarities between genera identification is very difficult, the aim of the present study is to provide the taxonomic characters for the delimitation of the taxa of subtribe Loliinae. We used scanning electron microscopy (SEM) techniques for the evaluation of the lemma and palea surface micromorphology for 33 species of this subtribe. Multivariate statistical analysis was used to show the species groupings. Factor analysis based on the principal component analysis showed the diagnostic importance of each of the characters. The lemma and palea epidermal patterns of Castellia, Festuca, and Lolium were examined, and results revealed that Lolium and Vulpia sensu lato species made separate groups nested in the Festuca clusters. The length of the long cell of the lemma, prickle in the lemma and palea, the wall shape of long cells of the lemma, wax type, silica bodies of lemma and palea, and the short cells in palea were important diagnostic characters for the species studied. The measured and evaluated set of lemma and palea micromorphological features was unable to provide the delimitation of the Festuca genus as subgeneric or sectional level. Present observations illustrated a heterogeneous assemblage as Festuca that needs further study for delimitation.

Automated summary

The subtribe Loliinae, consisting of around 600 species, is one of the largest subtribes of the Poeae tribe. Festuca genus, closely related to Lolium, Castellia, and Vulpia, has a complex taxonomic history. The study used SEM techniques to evaluate micromorphology of lemma and palea surfaces of 33 species in the subtribe, revealing difficulties in identification due to morphological similarities. Some micromorphological features were found to be important for species identification, but overall, the features were not sufficient for subgeneric or sectional delimitation of the Festuca genus.