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My research focus mainly on the evolution and biogeography in the flowering plant order Gentianales, which includes:
My projects include research in the following areas:
The gentian family (Gentianaceae) Commonly known gentians are the deep-blue flowered alpine gentians (Gentiana), the pink-flowered centaury (Centaurium) and marsh-pink (Sabatia), as well as the cut flowers and potted plants of lisianthus (Eustoma) and Persian violet (Exacum). I am using phylogenetic data from gentians to understand the biogeography of plants from tropical areas, especially in Latin America (the Neotropics). The gentian family comprises ca. 87 genera and ca. 1650 species classified in six tribes. It is distributed worldwide, but has the highest number of genera and greatest morphological diversity in the tropical areas of the world. My 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). Publications: Struwe & Albert, 2002 Classification and monograph of the gentian family The book Gentianaceae - Systematics and Natural History (Struwe & Albert, 2002) includes chapters written by experts on evolution, biogeography, and morphological and molecular-based phylogenetic studies, phytochemistry and pharmacology, seed anatomy, and palynology. The book also includes a new family-level classification of the gentians written in collaboration with Victor Albert (Oslo, Norway), Joachim Kadereit (Mainz, Germany), Jens Klackenberg (Stockholm, Sweden), the late Siwert Nilsson (Stockholm, Sweden), Mike Thiv (Zurich, Switzerland), and Bernhard von Hagen (Germany). This is the first classification of gentians since Ernst Gilg’s system from 1895. It is also the first comprehensive treatment of the family since Grisebach’s gentian monograph in 1839, which was published in Latin. Publications: Pringle & Struwe, in press; Struwe & Albert, 2002; Struwe et al., 2002 Neotropical biogeography: geology, speciation and geography in Latin America Neotropical biogeography is one of my main interests, focusing primarily on the tepuis and the lowland white-sand savannas (on nutrient-poor and ancient sediments, with vegetation known as Amazon caatinga) in the Amazon basin. The tepuis are flat-topped and sharp-cliffed mountains of the Guayana Highlands in eastern Venezuela, northern Brazil, and Guyana. I am working on 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? Are 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? What 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 Guayana Shield in the north)? The tribe Helieae and the genus Potalia are used as model organisms for these biogeographic studies. Publications: Mansion & Struwe, 2004; Struwe, 1999, in press; Struwe & Albert, 2002; Struwe et al., 2002, 2006 Evolution in tribe Helieae (Gentianaceae) The gentian tribe Helieae occur only in Latin America and include Calolisianthus, Chelonanthus, Irlbachia, Macrocarpaea, Symbolanthus, and Tachia, 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 tepui summits and their associated slopes with rainforest, 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 can be found, from hummingbirds in Symbolanthus and Lagenanthus, bats in some Chelonanthus and Macrocarpaea, insects in several genera, and hawkmoth pollination in Aripuana and Macrocarpaea. I aim at investigating 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. The traditionally difficult generic delimitations and species relationships in the group are being resolved using cladistic methods and modern molecular techniques. Graduate students Kate Lepis and Maria Fernanda Calio participate in this project. Publications: Gould & 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 Saccifolium (Gentianaceae; formerly Saccifoliaceae)The phylogenetic position of Saccifolium bandeirae from the mountain Sierra de la Neblina on the Brazilian-Venezuelan border, had been uncertain since its discovery decades ago when it was described as the sole member of the family Saccifoliaceae. Saccifolium has now been shown to be a member of the most basal clade of the Gentianaceae, the new tribe Saccifolieae, together with e.g., Curtia and the saprophytic genus Voyriella. Publications: Struwe & Albert, 2002; Struwe et al., 2002; Thiv et al., 1999 Evolution in Potalieae (Anthocleista, Fagraea, and Potalia; Gentianaceae) 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, African-Malagasy Anthocleista, and Asian-Australian-Pacific Fagraea (all in the Potalieae) are being investigated using morphological and molecular data. Potalia and its closely related genera Anthocleista and Fagraea 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. Potalia is restricted to the Neotropics and seven species are now recognized - as compared to only one species previously. Potalia is also the gentian that is most used pharmacologically by people in the New World. It is used against snake bites and other animal bites, poisonings, stomach aches, inflammations, fungal infections, fevers, and many other health problems. Publications: Struwe & Albert, 1997, 2002, 2004; Struwe et al., 1998, 2002 Flower development in gentiansOther areas of my research are 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 and Anthocleista 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. Publications: Struwe, 1999; Struwe & Albert, 2002; Struwe et al., 1997, 2002 Evolution in LoganiaceaeI 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) in Buddlejaceae (order Lamiales), Desfontainia in Desfontainiaceae, yellow jessamine (Gelsemium) in Gelsemiaceae (Gentianales), Sanango and Peltanthera in Gesneriaceae (Lamiales), and Retzia in Stilbaceae (Lamiales). Left in Loganiaceae proper are only 13 genera, namely Antonia, Bonyunia, Gardneria, Geniostoma, Labordia, Logania, Mitrasacme, Mitreola, Neuburgia, Norrisia, Spigelia, Strychnos, and Usteria. Graduate student Cynthia Frasier participates in this project. Publications: Albert & Struwe, 2002; Molina & Struwe, 2004; Struwe & Albert, 1997; Struwe & Motley, in press; Struwe et al., 1994. Additional research projects
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| DNA alignments and data from published works |
For questions or comments about this site, contact
struwe@aesop.rutgers.edu
Last updated:
08/20/2006
© 2004 Lena Struwe, Rutgers University. All rights reserved.