Sedge Research
My primary research interest is the systematics of Carex or sedges (family Cyperaceae), the world’s largest flowering plant genus (over 2100 species). Sedges are grass-like plants that grow on every continent except Antarctica. They occur in habitats ranging from marshes to deserts and they dominate many ecosystems, including tundra and savanna. Some species are habitat-specific, narrowly distributed, and of conservation concern, whereas others are ubiquitous weeds that occur in a variety of environments. Many species fill key ecological roles while others are economically important. Yet, sedges remain poorly known. Their reduced flowers and complicated patterns of morphologic variation make the identification of these plants challenging. As a result, many have avoided the study of sedges as too difficult.
Over the past decade, a marked upsurge of interest in sedges has occurred. Professional botanists, conservationists, and students have greatly increased our knowledge of the ecology, economics, and taxonomy of this fascinating group of plants with the most rapid strides being made in our understanding of evolutionary relationships. These phylogenetic studies show that Carex is comprised of five evolutionary lineages or “clades”: the Core Carex, Siderostictae, Schoenoxiphium, Vignea, and Caricoid Clades. Interestingly Carex, and its most diverse lineages, are sister to Southeast Asian species, many of which possess characters or character combinations that are rare or unique for their clades and the genus.
Despite having only a fraction of world sedge diversity (ca. 85 species), Vietnam possesses the largest number of these morphologically peculiar sedges making it key to understanding the evolution and radiation of this remarkably diverse group of plants. In 2012 and 2015, National Geographic Society sponsored expeditions allowed us to collect specimens and DNA samples from 40+ Carex taxa, including species that are new to science (Ford et al. 2017). Sedges were found in the greatest abundance in the granitic mountainous regions of northern Vietnam at elevations > 1000 m. Recent phylogenetic studies, conducted in collaboration with Julian Starr, University of Ottawa, have revealed major new lineages within the genus that are dominated by these morphologically unusual species (Starr et al. 2015). We now recognize Carex to be comprised of eight evolutionary lineages: Large Core Carex, Schoenoxiphium, Vignea, Caricoid, Small Core Carex, Siderostictae, Hypolytroides, and Dissitiflora, with the latter four clades being morphologically diverse and restricted to east Asia. Our research also suggests that northern Vietnam and adjacent regions may be the centre of origin for the world’s largest flowering plant genus. Ongoing studies are focused on increasing species and gene sampling for phylogenetic analyses and revising the taxonomy of the Vietnamese and Indochinese sedge flora.
In addition to our work on the sedges of Vietnam, we have been studying evolutionary relationships within the Vignea Clade (Ford et al. 2006, 2012), a taxonomically complex group of over 300 species. To date we have produced a detailed molecular phylogeny of this taxon using nrDNA sequences and amplified fragment length polymorphisms (AFLPs). Trends related to geography and evolution of inflorescence types were evident in our study. However, many groups had poor statistical support suggesting that this clade may have undergone recent radiation and diversification.
Finally, we have been revising the taxonomy of Carex sect. Phyllostachyae, a distinctive group of woodland species endemic to North America. As a result of our research, the number of species now recognized in this section doubled over a 10-year period (Ford et al. 2008). Intriguing question regarding inflorescence structure, character homology, cytology, and breeding systems require further study.
Orchid Research
Hybridization
is a naturally occurring phenomenon that can be a catalyst for
evolutionary change and speciation in plants. However, hybridization can
threaten the genetic purity of endangered species, especially when
these hybrids are vigorous and fertile. In collaboration with Dr. Anne
Worley, University of Manitoba, we are studying the population biology
of the globally endangered small white lady’s slipper (Cypripedium candidum) and the common yellow lady’s slipper (C. parviflorum)
in Canada. The goals of our research are to understand why
hybridization occurs and what the outcome of this process might be for
these species.
Preliminary studies of Manitoban populations indicated that individuals identified as C. candidum and C. parviflorum on the basis of their morphology are genetically distinct. Similarly, plants with a hybrid appearance are genetically intermediate. However, the genetic profile of some “pure” individuals suggests that cryptic hybrids are present in all populations (Worley et al. 2009). Ongoing studies will confirm the consistency of this pattern over the range of C. candidum.
We are also studying the reproductive biology of white and yellow lady’s slippers, and the influence of the surrounding floral community on hybridization and reproductive success. Our initial studies of fruit set and pollen viability indicate that Cypripedium candidum has much lower fertility than either hybrids or C. parviflorum. Future research will determine if this pattern is consistent over a wider geographic range.
Preliminary studies of Manitoban populations indicated that individuals identified as C. candidum and C. parviflorum on the basis of their morphology are genetically distinct. Similarly, plants with a hybrid appearance are genetically intermediate. However, the genetic profile of some “pure” individuals suggests that cryptic hybrids are present in all populations (Worley et al. 2009). Ongoing studies will confirm the consistency of this pattern over the range of C. candidum.
We are also studying the reproductive biology of white and yellow lady’s slippers, and the influence of the surrounding floral community on hybridization and reproductive success. Our initial studies of fruit set and pollen viability indicate that Cypripedium candidum has much lower fertility than either hybrids or C. parviflorum. Future research will determine if this pattern is consistent over a wider geographic range.