BALTIC FORESTRY NATURAL HYBRIDISATION WITHIN ELMS (ULMUS L.) IN LITHUANIA R. PETROKAS, V. BALIUCKAS Natural Hybridisation within Elms (Ulmus L.) in Lithuania RAIMUNDAS PETROKAS1 * AND VIRGILIJUS BALIUCKAS12 1 Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry, Liepu 1, LT-53101 Girionys, Kaunas distr., Lithuania 2 Aleksandras Stulginskis University, Faculty of Forestry and Ecology, Department of Forestry, Studentu 11, LT 53361 Akademija, Kaunas distr. Lithuania *Phone: 00370 37 547289, E-mail:
[email protected] Petrokas, R. and Baliuckas, V. 2012. Natural Hybridisation within Elms (Ulmus L.) in Lithuania. Baltic Forestry 18(2): 237246. Abstract Putative natural hybrids (Ulmus × hollandica) between the Smooth-leaved (Ulmus minor ssp. minor) and the Wych elm (Ulmus glabra) were observed in mixed forests along the rivers and rivulets around the central part of Lithuania. Eleven populations of elms (Ulmus L.) were studied to determine 1) the critical groups of phenotypes indicative for their taxonomic identity, 2) the variability of taxa from contact zones. Three characteristics for the trees and twenty one for their leaf, including nineteen applied by WinFOLIA 2004a programme, were used to describe each sample of the fifty eight and to ascertain the degree of affinity between samples. As a result of this approach, four taxa could be distinguished at the contact zones within elms. Three elm species and hybrids, Ulmus glabra, Ulmus minor, Ulmus laevis, and Ulmus × hollandica, were fairly satisfactorily distinguishable, but there is much overlap between the Wych elm and the Field elm in their characters that can be explained only by the equivalence of their statistically discriminant phenotypic distinctness.