Recent publications from the Les lab on plant systematics, for which voucher specimens are deposited in the CONN herbarium:
Ross T. G., C. F. Barrett, M. S. Gomez, V. K.-Y. Lam, C. L. Henriquez, D. H. Les, J. I. Davis, A. Cuenca, G. Petersen, O. Seberg, M. Thadeo, T. J. Givnish, J. Conran, D. W. Stevenson & S. W. Graham. 2016. Plastid phylogenomics and molecular evolution of Alismatales. Cladistics 32: 160–178. pdf
Abstract reads: Past phylogenetic studies of the monocot order Alismatales left several higher-order relationships unresolved. We addressed these uncertainties using a nearly complete genus-level sampling of whole plastid genomes (gene sets representing 83 protein-coding and ribosomal genes) from members of the core alismatid families, Tofieldiaceae and additional taxa (Araceae and other angiosperms). Parsimony and likelihood analyses inferred generally highly congruent phylogenetic relationships within the order, and several alternative likelihood partitioning schemes had little impact on patterns of clade support. All families with multiple genera were resolved as monophyletic, and we inferred strong bootstrap support for most inter- and intrafamilial relationships. The precise placement of Tofieldiaceae in the order was not well supported. Although most analyses inferred Tofieldiaceae to be the sister-group of the rest of the order, one likelihood analysis indicated a contrasting Araceae-sister arrangement. Acorus (Acorales) was not supported as a member of the order. We also investigated the molecular evolution of plastid NADH dehydrogenase, a large enzymatic complex that may play a role in photooxidative stress responses. Ancestral-state reconstructions support four convergent losses of a functional NADH dehydrogenase complex in Alismatales, including a single loss in Tofieldiaceae.
Razifard H., D. H. Les & G. C. Tucker. 2016. Evidence for the transfer of Elatine rotundifolia to Linderniaceae. Systematic Botany 41: 665–671. pdf
Abstract reads: Elatine rotundifolia was described in 2008 from Ecuador as a new species because of its unique morphology and geographical distribution. However, an examination of type material for E. rotundifolia suggested to us initially that this taxon had been assigned incorrectly to Elatine, despite some superficial similarity to that genus. This possibility was investigated using morphological and molecular data. We found that E. rotundifolia differed from other members of Elatine by several vegetative and reproductive features, which indicated a distant alliance closer to Linderniaceae (Lamiids; Asterids) rather than Elatinaceae (Fabids; Superrosids). We then conducted a phylogenetic analysis of DNA sequences from the internal transcribed spacer region, which included isotype material of E. rotundifolia, as well as various representatives of Elatinaceae, Linderniaceae, and other angiosperm clades. The molecular data resolved E. rotundifolia among several accessions of Micranthemum (Linderniaceae) in a position quite remote phylogenetically from accessions of Bergia and Elatine (Elatinaceae). From these results, we conclude that the name E. rotundifolia refers to a taxon that was misplaced in Elatine, and represents instead a member of Micranthemum (Linderniaceae), and possibly is synonymous with the aquatic species M. umbrosum.
Razifard H., G. C. Tucker, L. Ahart & D. H. Les. 2016. Noteworthy collections. California. Elatine americana. Madroño 63: 3–4.
King U. M. & D. H. Les. 2016. A significant new record for Hydrilla verticillata (Hydrocharitaceae) in central Connecticut. Rhodora 118: 306–309. pdf