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Abstract Detail

Systematics Section/ASPT

Fabillo, Melodina [1], Prentis, Peter [1], Thompson, John [2], Scharaschkin, Tanya [1].

Systematics of Tripogon (Poaceae:Chloridoideae) using morphological and molecular data, with emphasis on the Australian taxa.

Tripogon (Poaceae: Chloridoideae) is a genus of grasses with approximately 40 species distributed in Asia, America, Africa and Australia. Tripogon loliiformis, the only described species in Australia, exhibits extensive morphological variation across its geographic range, leading to the suggestion of it being multiple species. The leaf and inflorescence morphology of the Australian Tripogon (T. loliiformis) is reported to resemble that of the American species (T. spicatus) and the African species (T. minimus). Phylogenetic studies at the subfamily level, which have included only two Tripogon species, indicate that the genus is not monophyletic. To date, no phylogenetic study has been conducted for the genus Tripogon and very little is known about the Australian Tripogon.
This study aims to reconstruct the phylogeny of Tripogon to test the monophyly of the genus and the phylogenetic placement of the Australian taxa using morphological and molecular data. Ingroup consists of 70 Australian Tripogon sampled across its geographic range. Outgroups are chosen from representatives of main clades in the subfamily Chloridoideae. Eighty leaf and inflorescence morphological characters and four loci (trnL-F, ndhF, matK and ITS) are used. Four different morphological forms based on inflorescence length and the arrangement of spikelets are observed in the Australian Tripogon: a) long inflorescence with short, distant spikelets; b) long inflorescence with long and overlapping spikelets; c) short inflorescence with short overlapping spikelets; d) combination of long and short inflorescences. On the leaf and lemma of the Australian Tripogon, two types of subsidiary cell shapes (triangular and semi-circular) are seen and the outline of long cells is either Ω-shaped or U-shaped. The leaves of the Australian Tripogon have either macrohairs on both adaxial and abaxial surfaces or on the adaxial surface only. Parsimony analyses of morphological data show that Tripogon is monophyletic and consists of two large clades. Clade 1 contains T. spicatus, T. minimus and all Australian Tripogon. All other species of Tripogon form Clade 2. Parsimony analyses using chloroplast DNA, trnL-F, show that the Australian Tripogon is not monophyletic. T. spicatus and T. minimus are nested within it.

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1 - Queensland University of Technology, Brsibane, Queensland, Australia, School of Earth, Environmental and Biological Sciences, 2 George Street, Brisbane, QLD, 4001, Australia
2 - Queensland Herbarium, Brisbane Botanic Gardens Mt Coot-tha, Toowong, QLD, 4066, Australia

Tripogon loliiformis
morphological characters

Presentation Type: Oral Paper:Papers for Sections
Session: 48
Location: Elmwood/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 5:00 PM
Number: 48014
Abstract ID:352
Candidate for Awards:None

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