Donald H. Les

Donald H. Les
University of Connecticut | UConn · Department of Ecology and Evolutionary Biology

Ph.D.

About

285
Publications
53,088
Reads
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10,907
Citations
Citations since 2017
15 Research Items
2591 Citations
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
September 1999 - February 2000
The Commonwealth Scientific and Industrial Research Organisation
Position
  • Visiting Researcher
August 1992 - September 2019
University of Connecticut
Position
  • Professor (Full)
August 1986 - August 1992
University of Wisconsin - Milwaukee
Position
  • Professor (Associate)
Education
September 1981 - April 1986
The Ohio State University
Field of study
  • Botany
January 1977 - May 1980
Eastern Michigan University
Field of study
  • Biology
September 1972 - May 1976
Eastern Michigan University
Field of study
  • Biology (Plant Physiology)

Publications

Publications (285)
Article
Full-text available
Cuscuta plants that were observed growing entirely submersed and parasitizing the aquatic macrophyte Hygrophila polysperma in the San Marcos and Comal Rivers in Texas, are identified genetically as C. obtusiflora. This note documents the first molecular identification of any Cuscuta species naturally growing underwater or parasitizing a submersed a...
Article
Full-text available
Duckweeds comprise a distinctive clade of pleustophytic monocots that traditionally has been classified as the family Lemnaceae. However, molecular evidence has called into question their phylogenetic independence, with some authors asserting instead that duckweeds should be reclassified as subfamily Lemnoideae of an expanded family Araceae. Althou...
Article
Full-text available
Bacopa egensis is newly reported for the flora of Mexico and an updated key is provided for the Mexican Bacopa species. Bacopa egensis se registra por primera vez para la flora de México con una clave actualizada para las especies mexicanas del género Bacopa.
Chapter
Duckweeds (family Lemnaceae) comprise 37 angiosperm species, which are distributed among five genera. Although these tiny specimens represent the smallest flowering plants on earth, the group is practically ubiquitous in water bodies worldwide. The paucity of morphological features in duckweeds has made it difficult to elucidate their evolutionary...
Article
Premise: The submersed aquatic plant Hydrilla verticillata ("hydrilla") is important ecologically and economically due to its aggressive growth in both indigenous and nonindigenous regions. Substantial morphological variation has been documented in hydrilla, including the existence of monoecious and dioecious "biotypes." Whereas plastid sequence d...
Article
Ceratophyllum (Ceratophyllaceae) is among the most enigmatic of angiosperm taxa, with its phylogenetic placement changing almost continuously over the last few decades. Ceratophyllum spp. are difficult to identify using vegetative morphology alone, which is commonly all that is available for these highly clonal plants. A molecular phylogenetic appr...
Chapter
Seagrasses have evolved independently at least four times throughout their evolutionary history. All seagrasses are members of the monocot order Alismatales. A new molecular phylogenetic analysis, applying a molecular clock based on recently redefined fossil evidence, provides a framework for describing the timing and relationships of seagrass line...
Book
Aquatic Dicotyledons of North America: Ecology, Life History, and Systematics brings together a wealth of information on the natural history, ecology, and systematics of North American aquatic plants. Most books on aquatic plants have a taxonomic focus and are intended primarily for identification. Instead, this book provides a comprehensive overvi...
Article
Full-text available
The cosmopolitan genus Elatine (Elatinaceae) includes about 25 aquatic species of mostly diminutive aquatic plants, whose relationships have not been evaluated using a phylogenetic approach. The taxonomic study of this group has been complicated by the small stature of the plants, their minute reproductive structures, and their cosmopolitan distrib...
Article
Full-text available
The study of hybridization in aquatic plants is complicated by rarity of flower production, absence of roots, and asexuality. Elatine is a cosmopolitan genus of aquatic flowering plants with about 25 species worldwide. Historically, there has been little concern regarding hybridization in the genus due to the prevalence of autogamy (i.e. self-polli...
Article
A new species, Blyxa mangalensis from the low altitude coastal lateritic plateau of the west coast of South India is described and illustrated. It differs from B. senegalensis in its 12 stamens, globose anthers with connective appendages, absence of petals in the female flower, distinctly longer style and 9 – 10 longitudinal-ridged seeds.
Article
Full-text available
A morphometric analysis of Sri Lankan Aponogeton was performed in order to clarify species delimitations and to facilitate their identifications by comparing states coded for 61 vegetative and reproductive characters. Both cluster analysis and principal coordinate analysis resolved five discrete phenetic groups within the genus in the island. Four...
Article
The aquatic monocotyledon genus Aponogeton Linnaeus f. (1781[1782]: 32) (Aponogetonaceae) consists of about 57 species distributed mainly in the tropical or subtropical regions of the Old world (Chen et al. 2015). Aponogeton natans (Linnaeus 1767: 227) Engler & Krause (1906: 11) is the type species of the genus and occurs in India, Pakistan and Sri...
Article
Full-text available
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...
Article
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...
Article
Full-text available
Nymphoides grayana (Menyanthaceae) in Florida verified by DNA and morphological data. J. Torrey Bot. Soc. 142: 325–330. 2015.—In the genus Nymphoides (floating-heart), at least six native and naturalized species are known to occur in the USA. Among the native species is Nymphoides humboldtiana, a species recently confirmed to reach its northern ran...
Article
Full-text available
Fifteen Najas flexilis collections were made in Alaska during the summer of 2012, with 13 of the stations representing either new or formerly undocumented localities for this imperiled Alaskan species. These field collections characterize the Alaskan habitats of N. flexilis as shallow water sites (,1.5 m) with sand-dominated substrates (71% of site...
Article
Full-text available
The world of 120 million years ago was one of dynamic biological processes. During that time the flowering plants emerged as the dominant global floristic element, a transformative event that ultimately altered the character of the entire planet. Understandably, the rapid rise of angiosperms has intrigued paleoecologists and evolutionary biologists...
Article
Genetic studies of nonindigenous populations can help to determine their geographical origin, whethersingle or multiple introductions have occurred, and provide evidence of hybridization. We broadly sur-veyed Najas minor populations at several nuclear and chloroplast loci. Sequence data were obtained fromnonindigenous N. minor populations in North...
Article
Full-text available
Ceratophyllum platyacanthum Cham. subsp. oryzetorum (Kom.) Les (Ceratophyllaceae) is recorded for the first time from Kashmir Himalaya and India. The species differs from its closely related taxon, Ceratophyllum demersum, in having smaller leaves and the fruit with a facial spine. A comparison between Ceratophyllum demersum and C. platyacanthum sub...
Article
Full-text available
Genetic studies of nonindigenous populations can help to determine their geographical origin, whether single or multiple introductions have occurred, and provide evidence of hybridization. We broadly surveyed Najas minor populations at several nuclear and chloroplast loci. Sequence data were obtained from nonindigenous N. minor populations in North...
Article
Full-text available
Plants that have adapted to grow as submersed aquatics are relatively rare among angiosperms, yet they represent a convergent strategy that has evolved in many groups. Asteraceae tribe Eupatorieae include a number of obligate wetland species, but only three genera (Gymnocoronis, Sclerolepis, and Shinnersia) routinely grow submersed. We conducted a...
Article
Nuclear DNA sequence data are essential for obtaining a complete understanding of plant species relationships, yet these data have been conspicuously absent from phylogenetic analyses of Lemnaceae (duckweeds). Using a modified Sanger sequencing protocol, we obtained DNA sequences of duckweed nuclear ribosomal regions, including 18S and 26S rDNA gen...
Conference Paper
Most molecular evidence points to a root of flowering-plant phylogeny that divides the angiosperm crown group into Amborella vs. all remaining species. However, a subset of analyses have persistently recovered alternative arrangements, typically connecting the root node between Amborella plus water lilies, vs. all other angiosperms. These results m...
Article
Full-text available
Unlabelled: • Premise of the study: The discontinuous North American distribution of Najas gracillima has not been explained satisfactorily. Influences of extirpation, nonindigenous introduction, and postglacial migration on its distribution were evaluated using field, fossil, morphological, and molecular data. Najas is a major waterfowl food, a...
Article
Full-text available
The re-colonization of aquatic habitats by angiosperms has presented a difficult challenge to plants whose long evolutionary history primarily reflects adaptations to terrestrial conditions. Many aquatics must complete vital stages of their life cycle on the water surface by means of floating or emergent leaves and flowers. Only a few species, main...
Data
Mauve alignment of the chloroplast genome structures among the order Alismatales using Acorus americanus as the reference. The color-coded boxes represent genome segments. In the diagram the lower boxes represent the genes transcribed in reverse direction. Genes are color-coded: white, protein coding genes; green, tRNA; red rRNA; pink boxes, IR. Nu...
Data
Primer sets used in the chloroplast genome of Najas flexilis for amplification and Sanger sequencing of assembly gaps, low coverage areas and junctions. (XLS)
Article
Tracing the evolution of one of the most ancient major branches of flowering plants, this is a wide-ranging survey of state-of-the-art research on the early clades of the monocot phylogenetic tree. It explores a series of broad but linked themes, providing for the first time a detailed and coherent view of the taxa of the early monocot lineages, ho...
Article
Full-text available
Florida hydrilla populations have shown an alarming increase in resistance to fluridone, an herbicide used extensively for controlling invasive US hydrilla populations. A rapid PCR and sequencing method was developed to identify and screen hydrilla genomic DNA for three previously identified phytoene desaturase (pds) gene mutations that confer resi...
Article
Outcrossing in the aquatic genus Nymphoides (about 50 species) is promoted by various sexual conditions including dimorphic heterostyly (most species) and dioecy (four species). In eastern North America, Nymphoides aquatica and Nymphoides cordata are dioecious sister species that differ only slightly by their leaf pigmentation and texture, adventit...
Article
Full-text available
Although chloroplast transcriptional and translational mechanisms were derived originally from prokaryote endosymbionts, chloroplasts retain comparatively few genes as a consequence of the overall transfer to the nucleus of functions associated formerly with prokaryotic genomes. Various modifications reflect other evolutionary shifts toward eukaryo...
Conference Paper
Full-text available
Among aquatic plants, Nymphoides species have some of the widest variation in range sizes, vegetative habits, and reproductive systems. Worldwide the genus comprises about 50 species that occupy temperate and tropical habitats. Besides having evolved an array of inflorescence architectures to support their largely entomophilous flowers, Nymphoides...
Conference Paper
Elatine L. (Elatinaceae Dumortier; waterworts) is a cosmopolitan genus of about 25 aquatic plant species in the order Malpighiales. The genus is interesting taxonomically for two main reasons. First, no systematic studies have been made on the genus using recently available molecular techniques. Second, two species from this genus (E. triandra Schk...
Article
Species of the aquatic genus Nymphoides have distinct and highly modified inflorescence architectures in which floating leaves support aerial flowers. Three inflorescence types exist in Nymphoides, and these differ by their relative elongation of internodes and the number of flowers per node. We compared organ composition and arrangement among the...
Article
Full-text available
Global seagrass losses parallel significant declines observed in corals and mangroves over the past 50 years. These combined declines have resulted in accelerated global losses to ecosystem services in coastal waters. Seagrass meadows can be extensive (hundreds of square kilometers) and long-lived (thousands of years), with the meadows persisting p...
Article
Full-text available
Nymphoides (Menyanlhaceae) plants from the Nueces River, Uvalde County, Texas, previously identified as N. indica (L.) Kuntze, are determined genetically to be identical to N. humboldtiana (Kunth) Kuntze specimens. This report documents the first record of the species not only in Texas but also in the United States.
Article
Full-text available
The uncommon reproductive system of dioecy is somewhat widespread in Solanaceae, being exhibited by members of five genera within this family. These members represent, however, only around 1% of species within the Solanaceae. The highest incidence of dioecy is found in the genus Solanum, where around 15 species have been described as consisting of...
Article
Full-text available
Abstract—The cosmopolitan genus Nymphoides contains approximately 50 species that vary considerably in growth habit, inflorescence architecture, and in vegetative, floral, and seed morphology. We undertook a phylogenetic study of 31 Nymphoides species, including all species native to Australia, to evaluate interspecific relationships and to infer t...
Conference Paper
Full-text available
Najas marina is a cosmopolitan aquatic monocot currently viewed as comprising 12 subspecies with six varieties. This is the only dioecious species in an otherwise monoecious group of annual hydrophiles and resolves phylogenetically as the sister to the remainder of the genus. Three distinct karyotypes have been reported for N. marina, including one...
Conference Paper
Full-text available
Increasingly, procedures to facilitate plant identification have become sought after, especially as the level of botanical expertise dwindles while infestations of invasive species multiply. Aquatic plants are particularly difficult to identify, even to genus, as they often are found in vegetative condition where few distinctive characteristics are...
Conference Paper
Full-text available
Najas flexilis (waternymph) is a monoecious, hydrophilous annual. Unlike many submerged aquatic plants it cannot reproduce vegetatively. Although circumboreal in distribution, N. flexilis is rare in the European portion of its range and is protected under European Union law. To date little genetic information has been available for this aquatic spe...
Article
Full-text available
New World Podostemaceae (riverweeds) comprise approximately 135 species in 21 genera, most of which are of tropical distribution, shed pollen in monads, and belong to subfamily Podostemoideae. We undertook a phylogenetic study of Neotropical Podostemoideae using molecular (ITS, rbcL, trnL) and morphological data, to assess the monophyly of genera a...
Article
Full-text available
Nymphoides is a genus of approximately 50 species worldwide, and arguably achieves its greatest diversity in tropical northern Australia, where most of the 20 native species occur. Species found at temperate latitudes are restricted to the eastern half of the country; of these, three (N. crenata, N. geminata, N. indica) also occur in the tropics, a...
Article
Full-text available
This paper reviews and summarises the important contributions made to the study of aquatic angiosperms by the Australian botanist Surrey W. L. Jacobs, based largely on the personal experiences of the author. His field-oriented research resulted in the publication of more than 75 technical books and papers on aquatic and wetland plants, 38 newly nam...
Article
Full-text available
The present-day distributions of Ceratophyllum demersum and C. echinatum are useful in interpreting the Quaternary distributional history of aquatic plants. East–west North American disjunct distributions of submersed hydrophytes are probably due to incomplete interglacial migrations. Widespread species such as C. demersum have successfully bridged...
Article
Full-text available
Pollination by water (hydrophily) is a highly specialized mechanism that occurs rarely among aquatic angiosperms, which mainly retain the reproductive systems reminiscent of their terrestrial ancestors. Hydrophily is abiotic and typically associated with unisexual flowers, factors that predictably would promote xenogamy and outcrossing. Yet, there...
Article
Full-text available
Specimens of Villarsia cambodiana (Menyanthaceae), the only tropical Villarsia species, were collected from Vietnam, where the species had not been recorded. Molecular data were used to evaluate the phylogenetic position of V. cambodiana relative to 31 other Menyanthaceae taxa representing 11 species of Nymphoides and every species of Liparophyllum...
Article
Full-text available
The angiosperm genus Myriophyllum (Haloragaceae) is among the most species-rich genera of aquatic core-eudicots. Myriophyllum has a cosmopolitan distribution with its center of diversity in Australia (> 37 endemics). The widespread invasive species of the genus (M. aquaticum, M. heterophyllum, and M. spicatum) have drawn attention from internationa...
Article
Systematic studies have clarified interspecific relationships in Zostera, but also allow for different but phylogenetically compatible classifications. Recently, several new species have been assigned to the genus Heterozostera, which some prefer to retain as a subgenus within Zostera; thus, if this taxonomic interpretation is followed, appropriate...
Article
Full-text available
Potamogeton is a taxonomically problematic genus of aquatic monocotyledons, which has received limited phylogenetic study using molecular data. The group is known for extensive vegetative plasticity, confusing patterns of morphological variation and propensity for hybridization. Potamogeton gemmiparus and P. vaseyi are of conservation concern in No...
Article
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Menyanthaceae species in Australia for- merly belonging to the genus Villarsia Ventenat, which morphological and molecular data have shown to be paraphyletic, are provided with new combina- tions in Liparophyllum Hooker f. and the novel genus Ornduffia Tippery & Les: L. capitatum (Nees ex Lehmann) Tippery & Les; L. congestiflorum (F. Mueller) Tippe...
Article
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The causes, consequences and correlates of dioecy have been the subject of much discussion since the days of Darwin. Several recent authors have stressed the importance of informing this body of theory, with studies focusing on lineages in which both dioecy and hermaphroditism are present. The genus Solanum is an ideal group for analysis, because d...
Article
Full-text available
Aponogeton is an important genus whose species are cultivated widely as ornamental aquatic plants. Although a fairly recent monograph has been published, the genus remains poorly studied systematically. We conducted a phylogenetic survey of Aponogeton that focused on relationships among the nine native Australian species as well as their relationsh...
Article
Full-text available
Previous taxonomic treatments of the family Zosteraceae in Australia/New Zealand have recognized Heterozostera tasmanica (monotypic) and four Zostera species all belonging to subgenus Zosterella: Z. capricorni, Z. muelleri, Z. mucronata, Z. novazelandica. Zostera has always been taxonomically problematic in Australia, where researchers have express...
Article
Sequences of the nuclear internal transcribed spacer (ITS) regions ITS1 and ITS2 have been used widely in molecular phylogenetic studies because of their relatively high variability and facility of amplification. For phylogenetic applications, most researchers use sequence alignments that are based on nucleotide similarity. However, confidence in t...