Norris H Williams

University of Florida | UF · Department of Natural History

Floral innovations are key for pollinator specialization and play a significant role in plant diversification. Orchidaceae present many examples of floral innovations that allow its high degrees of pollinator specialization and promoted speciation. The rich neotropical genus Telipogon evolved an uncinate (=hook-like) viscidium on the pollinarium an...

Aim Orchidaceae is the most species‐rich angiosperm family and has one of the broadest distributions. Until now, the lack of a well‐resolved phylogeny has prevented analyses of orchid historical biogeography. In this study, we use such a phylogeny to estimate the geographical spread of orchids, evaluate the importance of different regions in their...

Dendrophylax porrectus is a leafless epiphytic orchid occurring in Florida (U. S. A.), the Greater Antilles, Mexico, Guatemala, and El Salvador. Previous morphological and phylogenetic analyses revealed considerable variation across its geographic range. This study examines morphological and molecular variation among populations of D. porrectus. Ph...

div class="page" title="Page 1"> Heterotaxis Lindl. comprises about 11 primarily epiphytic species ranging from the southeastern U.S.A. (Florida) and the Greater Antilles to Brazil, with most of the species occurring in Central and South America. This complex is characterized by a sympodial growth habit, with short rhizomes, lateral- ly compressed...

div class="page" title="Page 1"> Tribe Maxillarieae account for approximately 10% (>2800 species) of Orchidaceae and are a major com- ponent of the Neotropical epiphytic flora. Pollination systems include 1) male euglossine-bee fragrance rewards in four subtribes, 2) oil reward systems and mimicry in some groups, 3) nectar rewards in a wide range...

div class="page" title="Page 1"> El género Myrmecophila Rolfe ha sido tradicional- mente incluido dentro de un concepto amplio de Schomburgkia Lindl. Sin embargo, recientes recons- trucciones filogenéticas basadas en secuencias de ADN indican que el grupo es basal dentro del com- plejo de taxa alrededor de Cattleya Lindl. s.l. y sólo lejanamente r...

Earlier research has revealed that the ndh loci have been pseudogenized, truncated, or deleted from most orchid plastomes sequenced to date, including in all available plastomes of the two most species-rich subfamilies, Orchidoideae and Epidendroideae. This study sought to resolve deeper-level phylogenetic relationships among major orchid groups an...

Orchids are the most diverse family of angiosperms, with over 25 000 species, more than mammals, birds and reptiles combined. Tests of hypotheses to account for such diversity have been stymied by the lack of a fully resolved broad-scale phylogeny. Here, we provide such a phylogeny, based on 75 chloroplast genes for 39 species representing all orch...

With approximately 200 species, the tribe Sobralieae is a dominant and common Neotropical group of orchids, yet little is known of variation in floral morphology as it relates to their pollination. As currently circumscribed, the tribe includes four genera that differ considerably in flower size and morphology: Elleanthus, Epilyna, Sertifera, and S...

Relationships among all subtribes of Neotropical Cymbidieae (Orchidaceae) were estimated using combined matK/ycf1 plastid sequence data for 289 taxa. The matrix was analyzed using RAxML. Bootstrap (BS) analyses yield 100% BS support for all subtribes except Stanhopeinae (87%). Generic relationships within subtribes are highly resolved and are gener...

The great majority of plant species in the tropics require animals to achieve pollination, but the exact role of floral signals in attraction of animal pollinators is often debated. Many plants provide a floral reward to attract a guild of pollinators, and it has been proposed that floral signals of non-rewarding species may converge on those of re...

Phylogenetic relationships within the orchid subtribe Oncidiinae sensu Chase were inferred using maximum likelihood analyses of single and multilocus DNA sequence data sets. Analyses included both nuclear ribosomal internal transcribed spacer DNA and plastid regions (matK exon, trnH-psbA intergenic spacer and two portions of ycf1 exon) for 736 indi...

Con más de 200 especies, la tribu de orquídeas Sobralieae es un componente importante de la riqueza florística de los neotrópicos. Actualmente esta tribu está constituída por cuatro géneros: Elleanthus, Epilyna, Sertifera, y Sobralia. Las plantas de éstos cuatro géneros generalmente producen tallos largos como cañas, pero difieren en forma drástica...

El genero Scaphosepalum (Orchidaceae: Pleurothallidinae) agrupa a 49 especies de distribucion tanto amplia como restringida las que muchas veces crecen en simpatria biotica en los bosques montanos neotropicales. Scaphosepalum alcanza su pico de diversidad en el norte de los Andes y constituye un sistema interesante para investigar el efecto que tuv...

Crassulacean acid metabolism (CAM) is a specialised mode of photosynthesis that improves atmospheric CO 2 assimilation in water-limited terrestrial and epiphytic habitats and in CO 2 -limited aquatic environments. In contrast with C 3 and C 4 plants, CAM plants take up CO 2 from the atmosphere partially or predominantly at night. CAM is taxonomical...

The three closely related species of blue huckleberries, i.e., Gaylussacia frondosa, G. tomentosa, and G. nana, which make up the Gaylussacia frondosa complex (sect. Decamerium, subsect. Frondosae), have been variously circumscribed and classified by North American systematists. This study aims to resolve the species relationships of the Gaylussaci...

Plastid DNA sequences have been widely used by systematists for reconstructing plant phylogenies. The utility of any DNA region for phylogenetic analysis is determined by ease of amplification and sequencing, confidence of assessment in phylogenetic character alignment, and by variability across broad taxon sampling. Often, a compromise must be mad...

Background/Question/Methods Crassulacean Acid Metabolism (CAM) is a water-conserving mode of photosynthesis present in 7% of vascular plant species worldwide. In tropical orchids, the CAM pathway is found in up to 50% of species. To better understand the role of CAM in species radiations and the molecular mechanisms of CAM evolution in orchids, we...

Floral morphology, particularly the angle of lip attachment to the column, has historically been the fundamental character used in establishing generic limits in subtribe Oncidiinae (Orchidaceae), but it has also been long recognized that reliance on this character alone has produced a highly artificial set of genera. In essence, lip/column relatio...

The orchid genus Dichaea, with over 100 species found throughout the neotropics, is easily recognized by distichous leaves on long stems without pseudobulbs and flowers with infrastigmatic ligules. The genus has previously been divided into four sections based primarily on presence of ovary bristles and a foliar abscission layer. The aim of this wo...

RESUMEN Se analizaron los patrones de distribución de las orquídeas endémicas del Ecuador con Sistemas de Información Geográfico (SIG) y Análisis Parsimónico de Endemismo (PAE) los cuales indican que la mayor parte de orquídeas endémicas se encuentran en los bosques montanos bajos. Adicionalmente sugieren que la composición florística del norte y s...

A molecular phylogeny was estimated for 23 species of the genus Stanhopea and its sister taxon the monotypic Embreea (Orchidaceae) using the internally transcribed spacer regions-1 and -2 (ITS). We compared the molecular phylogeny with data on floral fragrances and pollination biology. In a few instances, the fragrance data reflected the molecular...

Species' boundaries applied within Christensonella have varied due to the continuous pattern of variation and mosaic distribution of diagnostic characters. The main goals of this study were to revise the species' delimitation and propose a more stable classification for this genus. In order to achieve these aims phylogenetic relationships were infe...

Subsidiary cell formation in leaves of the Oncidieae begins with the production of a trapezoid cell on each side of the guard cell mother cell. The trapezoid cells are formed by oblique divisions in the tiles of cells next to the tile of cells containing the guard cell mother cell. The trapezoid cell usually divides unequally to form a subsidiary c...

Epidermal cells from adaxial leaf surfaces of 42 species of Paphiopedilum and 6 species of Phragmipedium were surveyed with the SEM. The surfaces of the cells are flat to papillose and often have various sculpturing patterns. To designate two orders of papilla size the terms ‘macropapilla’ and ‘micropapilla’ are proposed. Species exhibiting unornam...

The orchid genus Maxillaria is one of the largest and most common of neotropical orchid genera, but its current generic boundaries and relationships have long been regarded as artificial. Phylogenetic relationships within subtribe Maxillariinae sensu Dressler (1993) with emphasis on Maxillaria s.l. were inferred using parsimony analyses of individu...

In the large, pantropical family Melastomataceae, Rhexia is unique in having a temperate distribution. The species of Rhexia, the “meadow beauties,” are a common sight along roadsides and in open habitats in eastern North America, ranging from Nova Scotia to Florida and the West Indies and west to eastern Texas. In order to elucidate interspecific...

A recent phylogenetic analysis of four DNA regions for ca. 354 species of core Maxillariinae strongly indicate that the genus Maxillaria, as traditionally circumscribed, is grossly polyphyletic. We pre-sent a new phylogenetic classification for core Maxillariinae that recognizes 17 genera. Necessary realign-ments include: 1) resurrection of the gen...

As currently defined, the 24 species of Schoenocaulon occur in three disjunct areas: north central Florida (one species, S. dubium), southern Peru (portion of the range of S. officinale), and the region from southeastern New Mexico-Texas south to Venezuela; the 20 species endemic to Mexico are geographically restricted. Species delimitations, often...

Members of tribe Vandeae (Orchidaceae) form a large, pantropical clade of horticulturally important epiphytes. Monopodial leafless members of Vandeae have undergone extreme reduction in habit and represent a novel adaptation to the canopy environment in tropical Africa. Asia, and America. To study the evolution of monopodial leaflessness, molecular...

The fruits of Maxillaria nardoides are fusiform, 1–1.2 × 0.3 cm. Upon dehiscence, six valves separate completely at the apex, and a long cylindric mass (up to 6.5 cm long × 3 mm in diameter) of white hygroscopic trichomes (elaters) is extruded along with the seeds. This capillitium hangs limply from the fruit with its base clamped by the three plac...

We describe the use of forced-air space heaters for drying herbarium specimens with a setup that is simpler, lighter, safer, and more economical than most previously described portable dryers. We have tested this method during collecting trips in the tropics with excellent results. Access to electricity and a rain-protected site are the only requir...

The phylogenetic relationships of the orchid subtribe Zygopetalinae were evaluated using parsimony analyses of combined DNA sequence data of nuclear ITS 1 and 2 (including the 5.8s region and portions of the flanking 18s and 26s regions) and of the plastid trnL intron plus the trnL-F intergenic spacer and the plastid matK. Analyses of the three sep...

Se evaluaron las relaciones filogenéticas de Telipogon, Ornithocephalus y géneros afines (Orchidaceae: Oncidiinae) mediante análisis de parsimonia de datos de espaciadores de ADN ribosomal nuclear (nrITS) y de tres regiones de ADN de plastidios (matK, trnL-F y la región espaciadora intergénica atpB-rbcL). Además de un análisis de 81 OTU con ITS, se...

Piper auritum H.B.K. is commonly known in Panama as “Hinojo Sabalero. ” Its crushed leaves are used by the natives to catch fish during the dry season. Most of the fish thus caught have been identified as Brycon chagrensis, which is known as “Sábalo pipón.” It is presumed, on the basis of field observations by Jolly (1), who described this local fi...