Cladistic analysis of the tribe Bromeae (Poaceae) based on morphological characters in Iran

Abstract

This study is concerned with the morphological cladistic analysis of monotypic tribe Bromeae including the genus Bromus. To characterize taxonomic circumscription of the genus, its species and sectional relationships of 39 taxa belonging to 6 sections and 2 outgroups were evaluated. Based on the heuristic search for 26 morphologhical informative characters, Maximum Parsimony approach was used for phylogenetic analyses The data matrix was analyzed by reweighting characters method, rescaled consistency index and retention index. The results obviously indicate the monophyly of the genus Bromus and taxonomic circumscription of its sections but phylognetic relationships of many of the species within each section remain unresolved. The monotypic sect. Nevskiella (lemmas short, 3.5-5 mm long and awns 3-5 times the length of lemmas) is clearly separated from other sections of the genus Bromus. Old world taxa of the perennial sect. Pnigma are more closely related to sect. Ceratochloa. The annual sects. Genea (spikelets cuneiform, broader at top) and Bromus (spikelets ovate, elliptic or lanceolate tapering towards top, lemmas with 1-5(6) awns) are monophyletic. The present cladistic analysis confirms the incorporation of the genus Boissiera (lemmas with 7-9 awns) into the genus Bromus.

Keywords

• Bromus
• Clade
• Cladistic morphology
• Monophyletic
• Poaceae