Patterns of flower microstructural variation within the genus Bromus

Abstract

Twenty five species from four sections of the genus Bromus were evaluated by means of numerical analyses of characters of flower microstructures (lodicule, lemma, palea). Special development of lodicules (lobe and hairiness) and both glumellae (lemma and palea) similar in grasses evolutionarily close (Bromeae, Brachypodieae, Triticeae) was discovered. For most of the characters the original interspecific and intersectional relations were observed in a space of minimum spanning tree (MST). The evolutionary old section Pnigma occupies the largest space. Species of Pnigma having small chromosomes can be distinguished from those having large ones. The section Ceratochloa is scattered through the smallest space. The above points to the endemic evolution of high polyploids of the section. The sections Bromus and Genea are evolutionarily close and they distinctly overlap each other in the MST space. Bromus sterilis, B. catharticus and B. riparius are extremes in their own sections.