Abstract Detail

Systematics

Naczi, Robert [1], Neubig, Kurt Maximillian [2], Majure, Lucas [3], Abbott, J. Richard [4], Judd, Walter [5], Whitten, W. Mark [6].

Systematics of the Dichanthelium ensifolium clade (Poaceae: Paniceae).

Dichanthelium (Poaceae) is a species-rich genus of grasses most diverse in eastern North America, but also occurring in South America and Hawaii. Many species in the genus are ecologically important members of various plant communities, especially in North America. Taxonomy of the genus is highly controversial and knowledge of phyletic relationships is minimal. Hence, the genus is in critical need of a phylogenetic approach in order to solve remaining classification problems. We diagnose and present the first integrated morphologic and molecular phylogenetic analysis of a clade of Dichanthelium. Morphologic synapomorphies diagnosing this clade appear to be 1) vernal leaf blades with pale margin 0.05-0.2 mm wide and margin entire or minutely, sparsely denticulate (vs. the plesiomorphic state of pale margin absent, or present and denticulate), 2) vernal leaf blades short relative to culm height (vs. the plesiomorphic state of leaf blades relatively long), and 3) spikelets ≤1.7 mm long (vs. the plesiomorphic state of spikelets >1.7 mm long). We used field and herbarium observations; morphometric analyses; and molecular data obtained through Illumina HiSeq sequencing technology by “genome skimming” plastomes and Sanger sequencing of ITS, GBSSI, and rpl32-trnL to resolve the taxa within the clade, to infer their phylogenetic relationships, and to document their geography. Members of the D. ensifolium clade occur in southeastern North America, specifically the southeastern U.S.A., Cuba, and northern Central America. All of the members inhabit sunny, nutrient-poor habitats with sandy or peaty substrates, such as pinelands, savannas, and peatlands. Most of the species inhabit wetlands, but at least one shift has occurred into dry habitats. Our resolution of the D. ensifolium clade is a first step in achieving a stable classification for the entire genus based on objective, repeatable data and analyses.

1 - The New York Botanical Garden, Bronx, NY, 10458, USA
2 - Southern Illinois University Carbondale, Plant Biology, Carbondale, IL, 62901, USA
3 - Desert Botanical Garden, Department of Research, Conservation, and Collections, Phoenix, AZ, 85008, USA
4 - The New York Botanical Garden, Bronx, NY, 10458
5 - University of Florida, Florida Museum of Natural History, Gainesville, FL, 32611
6 - University Of Florida, Florida Museum Of Natural History, PO BOX 117800, Gainesville, FL, 32611-7800, USA, 352/273-1964

Keywords:
Dichanthelium
Poaceae
North America
morphometrics
molecular systematics.

Presentation Type: Oral Paper
Session: 45, Monocots part B/Basal Eudicots
Location: 200/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 2:45 PM
Number: 45006
Abstract ID:354
Candidate for Awards:None