Comparison of morphological variation indicative of ploidy-level in Phragmites australis (Poaceae) from Eastern North America.

ABSTRACT. Variation in ploidy levels in Phragmites australis is a welldocumented phenomenon although North American populations are less studied than European ones. It has been suggested, based on morphological measurements, that native and introduced P. australis subspecies in North America represent different ploidy levels. The objectives of this study were to assess whether guard cell size and stomatal density, morphological differences indicative of variation in ploidy level between native and introduced P. australis, are truly associated with different ploidy levels as measured by flow cytometry. Significant differences in guard cell size and stomatal densities were found between subspecies, with native plants having larger guard cells and lower stomatal density. However, no differences in 2C DNA content were found. Although these morphological measurements are significantly correlated with subspecies and can be added to the list of useful morphological characters distinguishing the two subspecies, it does not appear that they are accurate indicators of ploidy levels. Potential implications of these differences on the invasion biology of introduced P. australis are discussed

Your environment and what you can do about it

xvii+299hlm.;21c

The law of the roadside. : How to protect our landscape. Electric lines in public ways. Shade trees in public ways. Insect pests. Trespass to real estate.

Includes index."The first edition of this pamphlet was compiled by Augustus Hemenway and George W. Anderson, and was published in 1893." -- Explanatory note, signed: Richard M. Saltonstall, Warren Motley.Mode of access: Internet.Bound in: Miscellaneous publications (Massachusetts Society for Promoting Agriculture), as [v.2.9]UM copy has publisher's presentation inscription to the St. Botolph Club, Boston, on front free end-paper

Susceptibility of Native and Non-Native Common Reed to the Non-Native Mealy Plum Aphid (Homoptera: Aphididae) in North America

As black swallow-wort, Vincetoxicum nigrum L. Moench, and pale swallow-wort, V. rossicum (Kleopow) Barbar., spread throughout the northeastern United States and southern Canada, there is concern about the impact of these invasive plants on populations of the native North American monarch butterfly Danaus plexippus L. Recent laboratory studies in New York and Ontario, Canada, have found little or no oviposition by monarch butterflies on the two Vincetoxicum species. In Rhode Island, we found 10.5–21.7% oviposition on Vincetoxicum species relative to common milkweed Asclepias syriaca L. in choice tests and 11.9–20.3% in no-choice tests in 2 yr of laboratory testing. These results were supported by field cage trials where monarchs given a choice between V. nigrum and A. syriaca laid 24.5% of their eggs on V. nigrum. In surveys of three pasture fields in Rhode Island where relative coverage of A. syriaca exceeded that of V. nigrum by a 0.77:0.23 ratio, 15.4% of monarch eggs were found on V. nigrum plants. In V. nigrum stands with very little A. syriaca (6.25 stems/ha), monarch egg density on V. nigrum was found to be over five times greater than in the three mixed pasture fields. In none of our laboratory or field evaluations was there any survival of monarch larvae on Vincetoxicum species. It seems that in Rhode Island, Vincetoxicum species serve as an oviposition sink for monarch butterflies. These findings suggest that East Coast butterflies may differ in host selection from those in central New York and southern Ontario, Canada