A phylogenetic analysis of the monogenomic Triticeae (Poaceae) based on morphology

A cladistic analysis, primarily based on morphology, is presented from 40 d iploid taxa representing the 24 monogenomic genera of the Triticeae. Genera l problems related to the treatment of hybrids and supposedly allopolyploid heterogenomic taxa are highlighted. Special emphasis is given to taxa not traditionally included in Aegilops s.l. Most of the 33 characters used in t he analysis are coded as binary. The only four multistate characters in the matrix are treated as unordered. Three diploid species of Bromus are used as outgroup. The number of equally parsimonious trees found is very large ( approx. 170 000; length=107, ci=0.36, ri=0.75) and the strict consensus tre e has an expectedly low level of resolution. However, most of the equally p arsimonious trees owe their existence to an unresolved Aegilops clade. If t his clade is replaced by its hypothetical ancestor, the number of equally p arsimonious trees drops dramatically (48; length=78, ci=0.45, ri=0.76). Whe n trees for which more highly resolved compatible trees exist are excluded, only two trees remain. Bremer support is used as a measure of branch suppo rt. The trees based on morphology and on molecular data are largely incongr uent. (C) 2001 The Linnean Society of London.