On the taxa of the genus × Trisetokoeleria (Poaceae) in the Russian Arctic

Abstract

An amplified description of the Siberian Arctic species × Trisetokoeleria taimyrica Tzvelev is compiled, based on the study and measurements of about 100 reproductive shoots (10 herbarium sheets) stored in the Herbarium of the Komarov Botanical Institute RAS (LE), including the neotype designated by the authors and 4 authentic herbarium specimens identified by N. N. Tzvelev. The main distinctive characters of the three species of the genus × Trisetokoeleria are given in the table, taking into account additional data on × T. taimyrica. The difficulty of recognizing the × Trisetokoeleria species in nature (the use of optics is necessary) is complicated by a weak difference in key features, primarily between T. gorodkowii (Roshev.) Tzvelev and T. taimyrica. The third species, namely T. jurtzevii Prob., clearly differs from the other two by pubescent (hairy) inflorescence branchlets and longer awns. × T. taimyrica differs from × T. gorodkowii by narrower, few-flowered panicles, glumes of slightly (vs. strongly) unequal length, and acuminate (vs. obtuse) lemma tips, and from × T. jurtzevii by glabrous stem, panicle branchlets and lemmas, as well as by shorter awns and narrower few-flowered panicles. Its differences from postulated parent species are as follows: from Koeleria asiatica Pers. — a short straight awn extending below the lemma tip (vs. extending from the very tip of the lemma, that is sometimes observed in K. asiatica), and glabrous stems and panicle branchlets; from Trisetum agrostideum (Laest.) Fr.) — a very short, straight awn extending slightly below the lemma tip (vs. twice articulated and extending slightly above ½ or at upper ⅓ of the lemma), as well as spike-like panicles. A map of the localities of the three × Trisetokoeleria species is compiled.