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ON THE TAXONOMY OF THE GENUS « TRISETUM » PERS

1963; Taylor & Francis; Volume: 17; Issue: 2 Linguagem: Inglês

10.1080/00837792.1963.10669754

2169-4060

Jindřich Chrtek, Václav Jirásek,

Lichen and fungal ecology

SUMMARY The perennial species of the genus Trisetum Pers. are usually divided into two sections, Trisetum (= Eu-Trisetum Asch, et Gr.) and Trisetaera Asch, et Gr. The authors remove the species Trisetum gracile (Moris) Par1., T. glaciale Boiss. and T. antoni-josephii F.-Q. et Muñ. Med. from the section Trisetum and assign them to the new section Gracilia with the type species T. gracile. The mentioned species differ from the other species of the seotion Trisetum above all by their low growth and by their short, thick and tough leaf-blades. They further differ by the distribution of the sclerenchymatous tissue in the transverse seotion of the leaf-blade. In the species of the section Gracilia the sclerenchymatous tissue reaches to the cells of the endodermis of the vascular bundles of the 1st order only in the species T. glaciale and probably also in the species T. antoni-josephii, and that only on the abaxial side of the blade. In the species of the section Trisetum the sclerenchymatous tissue is developed much stronger, and in bundles of the 1st, 2nd, and also of the 3rd order, it reaches to the cells of the endodermis of the vascular bundles, and that not only on the abaxial side, but also on the adaxial side of the leaf-blade. The species of the section Gracilia are spread only in the western basin of the Mediterranean, and that T. gracile in the montane regions of Sardinia, and T. glaciale and T. antoni-josephii in the Sierra Nevada mountain range. In the concluding chapter the authors state the distinguishing characters of the individual species of the section Gracilia, and there is also a dichotomic key for their determination.