The Plant Press

Art by Alice Tangerini: Cyperus pulguerensis M.T. Strong

From Plant Press, Vol. 18, No. 4, October 2015.

Cyperus pulguerensis (Cyperacae) was published in “Monocots & Gymnosperms of Puerto Rico and the Virgin Islands” (Contr. U.S. Natl. Herb. 52: 1-415; 2005). The brush and ink illustration was drawn in 2005 from the holotype at the U.S. National Herbarium (Proctor & Thomas 43804, June 24, 1987, El Pulguero, Manati, Puerto Rico) and an isotype from the herbarium of the Departamento de Recursos Naturales y Ambientales in San Juan. Originally identified as Cyperus confertus, the type differed in the spikelet scales which have the carina prolonged at the apex as a straight thickened mucro versus a distinctly to slightly excurved cusp in C. confertus. This species and the beak-rush Rhynchospora depressirostris, are sedges endemic to the white sand areas of the Manati-Vega Baja area, north-central Puerto Rico. This is an area of high diversity where other rare and endemic plants are known to occur as well.

Flora of Oregon

From Plant Press, Vol. 18, No. 4, October 2015.

A revision of the genus Poa in Oregon, written by Rob Soreng and colleagues Barbara Wilson, Richard Brainerd and Nick Otting, was recently published in Flora of Oregon, Volume 1 (2015; BRIT Press, Fort Worth). This new book, edited by Stephen Meyers, Thea Jaster, Katie Mitchell and Linda Hardison, covers Pteridophytes, Gymnosperms, and Monocots, along with biographies of major plant collectors and details of the ecology of the state. All plant genera and about half the taxa are illustrated, and all species and infraspecies are mapped. More than 20 taxonomists contributed to the first volume of the first statewide flora for Oregon published since the second edition of Morton Peck's flora in 1961. Volumes 2 & 3 are expected in 2017 and 2020. Visit the Oregon Flora Project website for more information and data.

Canadian Populations of Magnolia acuminata Have Low Levels of Gene Flow

From Plant Press, Vol. 18, No. 4, October 2015.

By Elizabeth Jacobsen, Botany Intern

Magnolia acuminata, the cucumber tree, is not the social type. Even where it is widespread, it is never abundant, existing in small populations throughout its range. The northern end of the species distribution lies in Ontario, Canada, where around 200 trees occupy fragmented habitats consisting of small populations of no more than 50, and usually fewer, mature trees. It is considered endangered in Canada and critically imperiled in Indiana, Oklahoma, and Florida. Concerned about its lonely distribution, Elizabeth Zimmer joined Trent University biologists Cara Budd and Joanna Freeland to investigate the tree’s genetic diversity using DNA microsatellites, comparing Canadian populations with each other and with populations in the United States (across the heart of M. acuminata’s range). Their findings were published in Conservation Genetics. “For other groups of plants with this distribution,” comments Zimmer, “in some cases you see there have been bottlenecks, and that’s a stronger warning that you have to manage plants.”

Populations of Magnolia acuminata may become increasingly isolated and may experience reduced genetic diversity without intervention. (photo by R.A. Howard)

As it turns out, the northern populations of M. acuminata in Canada have lower levels of genetic diversity than populations across the United States. Zimmer explains, “may not be pollination that maintains genetic diversity, it may be seed dispersal.” The beetle species that pollinate the trees likely do not disperse as far as other major pollinating animals, but the plant’s seeds are likely dispersed greater distances by birds or in some cases waterways. However seeds must find suitable habitat to germinate, which can be a challenge in today’s altered and fragmented environments.

Canadian populations have little gene flow between them; many alleles are found only in one population or another. The trees are long-lived, not reaching fertility until they are 30 years old, and the genetic information in older trees may not represent the state of populations today. This is confirmed by lower levels of genetic diversity found in M. acuminata saplings. The information gathered in the study indicates that the most effective way to protect genetic diversity in peripheral populations is to protect the habitat and dispersers that could facilitate the exchange of seeds between populations.