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Abstract Detail

Systematics Section/ASPT

Romaschenko, Konstantin [1], Peterson , Paul M [1], Soreng, Robert J [1], Valdes Reyna, Jesus [2].

A molecular phylogeny and classification of Eriocoma and Ptilostipa (Poaceae: Stipeae).

The tribe Stipeae includes about 620 species distributed in temperate environments worldwide, ranging from cool and wet to dry and xeric. Most species are tussock-forming grasses characterized by having single-flowered spikelets and lemmas 5−9-veined often concealing the palea and terminating in an awn. Evolutionary relationships within the tribe Stipeae have not been fully elucidated and the generic circumscription has remained controversial. We conducted a molecular phylogenetic study of 102 species of Stipeae primarily in the New World using four plastid DNA (ndhF, rpl32-trnL, rps16-trnK, and rps16 intron) and nuclear ITS 1&2 sequences to infer relationships and revise the classification. In our phylogenetic tree, Achnatherum is polyphyletic and the North American species are in two highly-supported clades: the “Eriocoma group” with 20 species and “Ptilostipa group” with seven species. Achnatherum acutum, A. constrictum, A. diegoense, A. editorum, A. eminens, A. hirticulmis, and A. multinodis ("Ptilostipa group”) have elongated, leafy, bamboo-like culms that rebranch above the base whereas members of the “Eriocoma group” have unbranched culms with the leaves borne near the base. The “Ptilostipa group” is distributed primarily in Mexico and southwestern USA and the “Eriocoma group” is more widely distributed in temperate western North America. The molecular results clearly support the recognition of two genera within the North American species of Achnatherum. Nearly all species of the “Eriocoma” and “Ptilostipa” groups differ from Eurasian species of Achnatherum by having a ciliate crown of hairs at the summit of the lemma. In our new classification there are no indigenous New World species of Achnatherum.

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1 - Smithsonian Institution, Botany, MRC-166, National Museum of Natural History, P.O. Box 37012, Washington, DC, 20013-7012, USA
2 - Universidad Autonoma Agraria Antonio Narro, Botany, Saltillo, Coahuila, C.P. 25000, MEXICO

Phylogenetic classification
plastid DNA sequences

Presentation Type: Oral Paper:Papers for Sections
Session: 13
Location: Pines South/Boise Centre
Date: Monday, July 28th, 2014
Time: 2:45 PM
Number: 13006
Abstract ID:233
Candidate for Awards:None

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