The Gentian Research Network<\/strong><\/a> is a free, not-for-profit, web-based forum for worldwide research on the natural history and evolution of the flowering plant family Gentianaceae<\/a> (gentians).<\/p>\n View Gentian Photo Gallery<\/a><\/p>\n The focus of my research (starting when I was an undergraduate student) is the historical evolution and biodiversity of angiosperms, especially plants from the order Gentianales and its families: Apocynaceae (dogbanes and milkweeds), Gelsemiaceae (Carolina jessamine), Gentianaceae (gentians), Loganiaceae (strychnine family), and to a lesser degree Rubiaceae (coffee and madder family). I investigate species diversity, evolution, and biogeography based on phylogenetic reconstructions using anatomical, morphological, and molecular data. Much of my recent work has focused on the classification and phylogeny of the families Gentianaceae and Loganiaceae, for which I have provided the most recent international family classifications.<\/p>\n The gentian family is also the focus of my research in the evolution of morphology and New World biogeography. To understand the evolution of the gentian family I look at a group of plants and track their ancestors. In addition I follow changes in their looks and attributes through their evolution tens of millions of years into the past. I ask questions such as: How old are these species? Where did they evolve?\u00a0 How did they get there?\u00a0 Which traits have they inherited from their ancestors?\u00a0 Why do they look like this? How did they come to look like this? How do their flowers and fruits develop? What are their proper names and how many species are exist?\u00a0 Are they endangered?\u00a0 How are they useful to humans? Why do some grow in the mountains and some grow in rainforests or savannas?<\/p>\n I study these questions using modern molecular (DNA) and traditional (morphological) techniques. This requires field work for collecting new plant material, visits to herbaria in many countries to study specimens collected during the last 300 years, and work in my laboratory with DNA sequencing, herbarium material, computers, and microscopes. We also use methodologies such as histological preparations, SEM, GIS, statistical methods (multivariate statistics, etc.), light microscopy, and phylogenetic analyses (parsimony, Bayesian, and maximum likelihood). As part of my research I developed the Spatial Evolutionary and Ecological Vicariance Analysis (SEEVA) method with collaborators.<\/p>\n Our systematic botany research focuses mainly on the evolution and biogeography of the flowering plant order Gentianales, which includes:<\/p>\n <\/p>\n <\/p>\n What are gentians?<\/strong><\/p>\n The gentian family (Gentianaceae<\/a>), commonly known gentians, includes: deep-blue flowered alpine gentians (Gentiana<\/a><\/em>), the pink-flowered centaury (Centa<\/em>u<\/em>rium<\/em>) and marsh-pink (Sabatia<\/em>), as well as the cut flowers and potted plants of lisianthus (Eustoma<\/a><\/em>) and Persian violet (Exacum<\/em>). I use phylogenetic data from gentians to understand the biogeography of plants from tropical areas, especially in Latin America (the Neotropics).\u00a0\u00a0The gentian family comprises ca. 87 genera and ca. 1650 species classified into six tribes. Gentians are distributed worldwide, but has the highest number of genera, and greatest morphological diversity, in the tropical areas of the world.\u00a0\u00a0My research includes phylogenetic, biogeographic, taxonomic, and floristic projects using data derived from molecular, morphological, and anatomical studies (e.g. flower anatomy and development, palynology, seed anatomy, and DNA sequencing).<\/p>\n Publications:<\/strong>\u00a0Struwe & Albert, 2002 <\/p>\n Classification and monograph of the gentian family<\/strong><\/p>\n The book\u00a0Gentianaceae – Systematics and Natural History<\/em> (Struwe & Albert, 2002) includes chapters written by experts on the evolution, biogeography, morphological and molecular-based phylogenetic studies, phytochemistry and pharmacology, seed anatomy, and palynology of the gentian family. The book also includes a new family-level classification of the gentians written in collaboration with Victor Albert, Joachim Kadereit, Jens Klackenberg, the late Siwert Nilsson, Mike Thiv, and Bernhard von Hagen. This was the first classification of gentians since Ernst Gilg\u2019s system (1895). It was also the first comprehensive treatment of the family since Grisebach\u2019s (1839) gentian monograph, which was published in Latin.<\/p>\n The most recent worldwide family treatment will be published soon as part of the global Families and Genera of Vascular Plant series (in press).<\/p>\n Publications:<\/strong>\u00a0Struwe & Pringle, in press; Struwe & Albert, 2002; Struwe et al., 2002<\/p>\n <\/p>\n Neotropical biogeography: geology, speciation and geography in Latin America<\/strong><\/p>\n Neotropical biogeography is one of my main interests, focusing primarily on the tepuis and lowland white-sand savannas (on nutrient-poor and ancient sediments, with vegetation known as Amazon caatinga<\/em>) in the Amazon basin. The tepuis are flat-topped and sharp-cliffed mountains in the Guiana Highlands in eastern Venezuela, northern Brazil, and Guyana.\u00a0\u00a0I work to answer research questions such as: Are the montane species of the tepui summits derived from ancestral lineages present in lowland rainforests and white-sand savannas, or from montane areas, such as the Andes?\u00a0\u00a0Are species endemic to the nutrient poor and ancient lowland white-sand areas in the Amazonas the oldest, relictual remnants of isolated evolutionary branches of the gentian family tree?\u00a0\u00a0What are the biogeographic relationships between plants in the Andes, the Amazon Basin, the Caribbean, and the two ancient geological Shields in South America (the Brazilian Shield in the southeast and the Guiana Shield in the north)? The tribe Helieae<\/a>\u00a0and the genus\u00a0Potalia<\/em>\u00a0are used as model organisms for these biogeographic studies.<\/p>\n Publications:<\/strong>\u00a0Mansion & Struwe, 2004; Struwe, 1999, in press; Struwe & Albert, 2002; Struwe et al., 2002, 2006<\/p>\n <\/p>\n Evolution in tribe\u00a0Helieae<\/a> (Gentianaceae) Publications:<\/strong>\u00a0Gould & Struwe, 2004; Grant & Struwe, 2001, 2003; Grant et al., 2006; Struwe, 2003; Struwe & Albert, 1998, 2002; Struwe & Gould, 2004; Struwe et al., 1999, 2002, 2005<\/p>\n <\/p>\n Saccifolium<\/strong><\/a><\/em>\u00a0(Gentianaceae; formerly Saccifoliaceae)<\/strong><\/p>\n The phylogenetic position of\u00a0Saccifolium bandeirae,<\/em> from the Sierra de la Neblina mountain on the Brazil-Venezuela border, had been uncertain since its discovery decades ago when it was described as the sole member of the family Saccifoliaceae.\u00a0Saccifolium<\/em>\u00a0has now been shown to be a member of the most basal clade of the Gentianaceae, the new tribe\u00a0Saccifolieae<\/a>, together with e.g. Curtia<\/em>\u00a0and the saprophytic genus\u00a0Voyriella<\/em>.<\/p>\n Publications:<\/strong>\u00a0Struwe & Albert, 2002; Struwe et al., 2002; Thiv et al., 1999<\/p>\n <\/p>\n Evolution in\u00a0Potalieae<\/a>\u00a0(Anthocleista<\/em>,\u00a0Fagraea<\/em>, and\u00a0Potalia<\/em>; Gentianaceae)<\/strong><\/p>\n The tribe Potalieae was also excluded from Loganiaceae, and is now placed in the Gentianaceae, a strongly supported position based on molecular, morphological, anatomical, and phytochemical data. Phylogenetic and biogeographic relationships between and within Potalia<\/em>, African-Malagasy\u00a0Anthocleista<\/em>, and Asian-Australian-Pacific\u00a0Fagraea<\/em>\u00a0(all in the Potalieae) are being investigated using morphological and molecular data.\u00a0Potalia,<\/em>\u00a0and its closely related genera\u00a0Anthocleista<\/em>\u00a0and\u00a0Fagraea<\/em> of Potalieae, are tropical woody genera with showy flowers and fleshy or leathery berries, whereas most gentians are smaller herbs or shrubs with dry capsular fruits.\u00a0\u00a0Potalia<\/em> is restricted to the Neotropics, and seven species are now recognized, compared to the only one species recognized previously.\u00a0 Potalia<\/em>\u00a0is also the gentian that is most used pharmacologically by people in the New World.\u00a0\u00a0It is used against snake bites and other animal bites, poisonings, stomach aches, inflammations, fungal infections, fevers, and many other health problems.<\/p>\n Publications:<\/strong>\u00a0Struwe & Albert, 1997, 2002, 2004; Struwe et al., 1998, 2002<\/p>\n <\/p>\n Flower development in gentians<\/strong><\/p>\n My research also extends to studying floral and fruit development in Gentianaceae. I investigate postgenital fusion of ovaries, development of berries vs. capsules, and anatomy and vascularization of flowers in the tribe Helieae and Potalieae. Another research project is early flower development of the supermerous flowers of Potalia<\/em>\u00a0and\u00a0Anthocleista\u00a0<\/em>of tribe Potalieae. Their unique flowers have 8-16 corolla and stamen parts instead of the usual 4 or 5 lobes\/stamens characteristic for most other gentians.<\/p>\n Publications:<\/strong>\u00a0Struwe, 1999; Struwe & Albert, 2002; Struwe et al., 1997, 2002<\/p>\n <\/p>\n Evolution in Loganiaceae<\/strong><\/p>\n I have also been working on the systematics of the tropical and subtropical family Loganiaceae in its older, traditional and larger circumscription. Nowadays, several former Loganiaceae genera are placed in other families, for example: the butterfly bush (Buddleja<\/em>) in Buddlejaceae (order Lamiales),\u00a0Desfontainia<\/em>\u00a0in Desfontainiaceae, yellow jessamine (Gelsemium<\/em>) in Gelsemiaceae<\/a>\u00a0(Gentianales),\u00a0Sanango<\/em>\u00a0and\u00a0Peltanthera<\/em>\u00a0in Gesneriaceae (Lamiales), and\u00a0Retzia<\/em>\u00a0in Stilbaceae (Lamiales). Left in\u00a0Loganiaceae<\/a> proper are only 13 genera, namely Antonia<\/em>,\u00a0Bonyunia<\/em>,\u00a0Gardneria<\/em>,\u00a0Geniostoma<\/em>,\u00a0Labordia<\/em>,\u00a0Logania<\/em>,\u00a0Mitrasacme<\/em>,\u00a0Mitreola<\/em>,\u00a0Neuburgia<\/em>,\u00a0Norrisia<\/em>,\u00a0Spigelia<\/em>,\u00a0Strychnos<\/em>, and\u00a0Usteria<\/em>. Graduate student\u00a0Cynthia Frasier<\/a>\u00a0participates in this project.<\/p>\n Publications:<\/strong>\u00a0Albert & Struwe, 2002; Molina & Struwe, 2004; Struwe & Albert, 1997; Struwe & Motley, in press; Struwe et al., 1994.<\/p>\n <\/p>\n Gentianales: trnL sequence matrix<\/a> (Struwe et al. 1999; 2002)<\/p>\n Gentianales – matK<\/a> (Struwe et al., 2002)<\/p>\n Gentianales – trnL intron and matK, combined<\/a> (Struwe et al., 2002)<\/p>\n Symbolanthus and Wurdackanthus: 5S-NTS<\/a> (Gould & Struwe, 2004)<\/p>\n 1. Gentianales – trnL intron<\/strong><\/p>\n Data: aligned trnL intron sequences from Gentianales; Apocynaceae (incl. Asclepiadaceae), Gelsemiaceae, Gentianaceae, Loganiaceae (incl. Geniostomaceae), Rubiaceae, Saccifoliaceae, and Strychnaceae (incl. Antoniaceae), and some outgroups outside Gentianales. For GENBANK accession numbers see Struwe et al. (2002). Gaps are indicated with “-“; “?” indicates missing data. First four letters of taxon name indicates genus, next four species name.<\/p>\n Matrix type: Parsimony jackknife format (Xac), text-only.<\/p>\n References: Struwe, L., J. Kadereit, J. Klackenberg, S. Nilsson, M. Thiv, K. B. von Hagen, and V. A. Albert. (2002) Systematics, character evolution, and biogeography of Gentianaceae, including a new tribal and subtribal classification. In: Struwe, L. & V. A. Albert, eds. Gentianaceae \u2013 Systematics and Natural History. Cambridge University Press, Cambridge. See also: Thiv, M., L. Struwe, V. A. Albert, & J. W. Kadereit. 1999. The phylogenetic relationships of Saccifolium bandeirae Maguire & Pires (Gentianaceae) reconsidered. Harvard Papers in Botany 4: 519-526.<\/p>\n Contact person: Dr. Lena Struwe, lena.struwe@rutgers.edu<\/p>\n Date posted on WWW: 1998<\/p>\nEvolution of Gentians and Gentian Relatives<\/h2>\n
\n
More Specifics on Our Lab’s Taxonomic Research in Gentianales<\/h2>\n
\n<\/strong><\/p>\n
\n<\/strong>The gentian tribe Helieae occur only in Latin America and include Calolisianthus<\/a><\/em>,\u00a0Chelonanthus<\/a><\/em>,\u00a0Irlbachia<\/a><\/em>,\u00a0Macrocarpaea<\/a><\/em>,\u00a0Symbolanthus<\/a><\/em>, and\u00a0Tachia<\/a><\/em>, etc. This monophyletic group of ca. 200 species contains both woody and herbaceous species and displays large variation in habit, leaves, flowers, and fruits. Many species are narrow endemics and restricted to small areas or habitats such as the tepui summits and their associated slopes, rainforests, or white-sand savannas, Andean mountain ridges, islands in the Caribbean, or highland savannas or forests in southeastern Brazil. Molecular data from the ITS and 5S-NTS DNA regions is used to resolve phylogenetic relationships within this group and to analyze biogeographical patterns. In the Helieae, many different pollinators<\/a> can be found, ranging from hummingbirds in Symbolanthus<\/em>\u00a0and\u00a0Lagenanthus<\/a><\/em>, bats in some\u00a0Chelonanthus<\/em>\u00a0and\u00a0Macrocarpaea<\/em>, insects in several genera, and\u00a0hawkmoth pollination<\/a>\u00a0in\u00a0Aripuana<\/a><\/em>\u00a0and\u00a0Macrocarpaea<\/em>. I investigate the evolution of floral traits and pollination syndromes, and also characters such as secondary woodiness, hairy leaves, inflorescence position, and pollen aggregation into tetrads and polyads in this group of gentians.\u00a0\u00a0The traditionally difficult generic delimitations and species relationships in the group are resolved using cladistic methods and modern molecular techniques.<\/p>\nGentian Molecular Systematics<\/h2>\n