Abstract Detail

Systematics

Schuster, Tanja M [1], Reveal, James L [2], Bayly, Michael J [1], Kron, Kathleen A [3].

Refining our understanding of Polygonaceae: new lineages and recircumscriptions in Polygonoideae.

The buckwheat or knotweed family Polygonaceae has a complex taxonomic history, and we are still working on large-scale questions regarding the evolutionary relationships of this group. Many members of Polygonaceae were once included in Polygonum L. and clarifying the circumscription and placement of genera split from this polyphyletic group is still in process. Polygonaceae include many primary successors or “weedy” species, and outside their native ranges Aconogonon polystachyum (Wall. ex Meisn.) M. Král, Persicaria perfoliata (L.) H.Gross, Rumex sagittatus Thunb., and species and hybrids of both Emex Neck. ex Campd. and Reynoutria Houtt. are pernicious invasives. Aside from resolving the classification of Polygonaceae, knowledge of the evolutionary relationships of invasive species is essential for predicting the potential of closely related species or hybrids to become noxious weeds that can have substantial economic impacts.
In this study, we address the relationships of several Polygonoideae genera including Aconogonon (Meisn.) Rchb., Emex, Fallopia Adans., Koenigia L., Oxygonum Burch. ex Campd., Polygonum, Reynoutria, and Rumex L. We clarify Polygonoideae phylogeny by building on an existing molecular dataset (nrITS, matK, and trnL-trnF) analysed with Maximum Likelihood and Bayesian methods.
Results indicate that the African endemic Oxygonum is an isolated lineage likely sister to all other members of Polygonoideae. The two species of Emex are nested in the Rumex clade and Rumex subg. Acetosa (Mill.) Rech.f. includes subg. Acetosella (Meisn.) Rech.f. and subg. Platypodium (Willk.) Rech.f.). Fallopia and Koenigia are polyphyletic with Aconogonon and Koenigia forming a clade, and Fallopia denticulata (C.C. Huang) Holub and F. cilinodis (Michx.) Holub falling outside the Fallopia s.s. clade. Fallopia denticulata forms a clade with Pteroxygonum Dammer & Diels, and we recognize this well-supported clade as Pteroxygoneae. Relationships within the Polygonum s.s. clade reflect geographic distribution with a North America clade sister to a clade containing cosmopolitan and Central Asian species. We confirm that Polygonella Michx. is included in Polygonum making Polygonella obsolete. Based on these results, we recognize Oxygoneae and Pteroxygoneae as tribes, include Aconogonon within Koenigia, merge Emex with Rumex, and recircumscribe Rumex subg. Acetosa. Knowledge of the phylogeny shows that no species of Polygonum s.s. are invasive, but at least three other clades in Polygonoideae include species from temperate Asia and Africa that are invasive in Australia, Europe, and North America. These are Persicarieae (e.g., Koenigia [Aconogonon] and Persicaria), Rumiceae (Rumex), and Reynoutriineae (Reynoutria but not Fallopia) in Polygoneae.

1 - The University of Melbourne, BioSciences 3/Botany, Parkville, Victoria, 3010, Australia
2 - Cornell University, L.H. Bailey Hortorium - School of Integrative Plant Science, Section of Plant Biology, 412 Mann Building, Ithaca, New York, 14853-4301, USA
3 - Wake Forest University, Department Of Biology, 1834 Wake Forest Road, WINSTON-SALEM, NC, 27106, USA

Keywords:
Caryophyllales
Invasive
herbarium specimen DNA extraction
Polygonum s.l.
Polygonella.

Presentation Type: Oral Paper
Session: 41, Basal Rosids & Rosids I
Location: 101/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 9:00 AM
Number: 41005
Abstract ID:321
Candidate for Awards:None