Taxonomic revision of Trisetum section Sibirica (Poaceae: Pooideae: Aveninae)

Abstract

A taxonomic revision of Trisetum sect. Sibirica is presented. We include descriptions and synonyms of each taxon from a study of 450 vouchers from 35 herbaria. Detailed morphometric descriptions, illustrations, distribution maps, identification key, and habitat data are given for each taxon. An identification key for all taxa of Trisetum sect. Sibirica is provided. Morphometric variation of the main characters is shown by box plots. Six names are lectotypified. We recognize six species of Trisetum in the section: T. aeneum, T. bifidum, T. henryi, T. scitulum, T. sibiricum, and T. turcicum. Two infraspecific taxa of T. sibiricum are recognized (T. sibiricum subsp. sibiricum and T. sibiricum subsp. litorale), while T. pauciflorum, T. sikkimense, and T. umbratile are reduced to synonyms of T. sibiricum subsp. sibiricum. Four of the six species of Trisetum sect. Sibirica are endemic to Eastern Asia and New Guinea, while T. turcicum grows in Turkey, the Caucasus, and Northern Iran, and T. sibiricum is widespread from Eastern Europe to Alaska and Canada.

Taxonomic Revision ofTrisetumSect.Trisetum(Poaceae: Pooideae: Aveninae) from Eurasia and North Africa

“…While the abaxial surface of the leaf blade often has a flat surface, the adaxial surface has ribs of varying depth (Metcalfe, 1960;Watson & Dallwitz, 1992). The xerophytic species of the section have deeper intercostal zones and associated ribs than the mesophytic ones, and the sclerenchyma girders and strands are well developed (Barberá et al, 2017a(Barberá et al, , 2017b. As indicated before, the midrib is not particularly marked in most of the species of the section but is strongly marked only in T. glaciale and T. gracile.…”

“…In Trisetum sect. Trisetum, as in the rest of the genus, the different characters of the leaf sheaths and leaf blades are variable in the same plant, depending on whether they are the basal or top culm leaf blades, or if they are young or mature (Barberá et al, 2017a(Barberá et al, , 2017b.…”

“…Acrospelion and Trisetum sect. Sibirica, the leaf blade features have been considered less important than those of the spikelet morphology for the taxonomy of the widespread species, due to the high variability of leaf blade traits (Barberá et al, 2017a(Barberá et al, , 2017b. The species of Trisetum sect.…”

“…This genus includes about 50 species that often form a significant part of the temperate and cold grasslands of the Northern Hemisphere, although they are also found in South America, Australia, and New Zealand. Their habitat varies according to their wide distributional range, and its species are found in open grasslands to shady areas of forests, high mountain meadows, and even the tundra (Hultén, 1959;Chrtek, 1965;Clayton & Renvoize, 1986;Randall & Hilu, 1986;Watson & Dallwitz, 1992;Finot et al, 2004Finot et al, , 2005aFinot et al, , 2005bBarberá et al, 2017aBarberá et al, , 2017b. Trisetum flavescens (L.) P.…”

“…and Trisetum sect. Sibirica (Chrtek) Barberá (Barberá et al, 2017a(Barberá et al, , 2017b. Six of the species of the section to which we dedicate the present work, Trisetum sect.…”