Volume 82 - Issue 1 (March 2017)

ABSTRACT We investigated the seed production and germination requirements of Penstemon oklahomensis, a species of conservation concern, to determine interannual variation in seed production and germination requirements. Mature seed capsules were collected and seed numbers counted in two successive years to assess interannual variation in seed production. A significant difference in number of seeds produced was found between collection years. Germination trials were conducted using the seed collected and subjected to three stratification treatments in two soil types. Seeds held over from the first collection year were also germinated to investigate viability loss a year after collection. Survival analysis was used to estimate the probability of seed germination under the treatment conditions. Germination probability was highest for seeds that underwent a cold stratification period of 60 days if sown the same year as they were collected, regardless of soil type used. Seeds held over a year had higher germination probability after a 30-day cold stratification period, but the probability was lower than the same treatment when the seeds were sown during the year collected. Seed production and germination requirements for P. oklahomensis are similar to other species of Penstemon, both in the Intermountain West and east of the Mississippi River.

ABSTRACT Apios priceana (Fabaceae) is a rare herbaceous perennial vine. Seed collection for ex situ conservation is difficult because seed production is sporadic. We investigated propagation by cuttings of A. priceana at Redstone Arsenal, Alabama. Two experimental factors were investigated: donor plant size (small vs. large) and month of cutting (May vs. June 2013). We also documented impact of cutting collection on donor plants by recording size and reproductive variables from both cut and uncut (control) plants. About one-third of cuttings formed tubers by May 2014; success did not differ due to donor plant size or month of cutting. However, May cuttings produced two-fold more tubers and had five-fold greater total tuber mass. Large donor plants grew more, and produced significantly more inflorescences and legumes than small donors. Cutting treatment alone did not significantly affect any donor plant variable, showing that donor plants recovered quickly after cuttings were taken. Significant interactions (for stem diameter and inflorescence production of donor plants) suggested that cutting more greatly stimulated regrowth of large plants cut in June. We conclude that propagation by cuttings can rapidly produce plants of this species for ex situ conservation, but there are trade-offs in outcomes. Cuttings taken in May have an advantage for tuber production (producing more tubers and greater tuber mass), whereas cuttings taken in June affect donor plants less (although this effect was modest). Overall, propagation by cuttings is a useful technique for this rare species as it produces new plants yet minimally impacts wild populations.

Supplemental Material File 1

Supplemental Material File 2

The Editorial Committee gratefully acknowledges and thanks the following  people who reviewed manuscripts for Castanea during 2016.

CASTANEA REVIEWERS FOR 2016
Rob Addington
Mac H. Alford
T. Wayne Barger
Craig Barrett
Vanessa Beauchamp
Z. Carter Berry
Jay F. Bolin
Robert Boyd
Gloria Caddell
Joshua W. Campbell
Julian Campbell
Matt Candeias
Brandi Cannon
Richard Carter
Xiongwen Chen
Lawrence J. Davenport
Alan R. Franck
Scott B. Franklin
John Freudenstein
Cecil Frost
Paul Gagnon
Donald Hagan
Rebecca E. Hale
Ryan Huish
Sean E. Jenkins
Suneeti Jog
Diana D. Jolles
Wesley M. Knapp
Karen Kuers
Claude Lavoie
Nancy Loewenstein
Urbatsch Lowell
Lucas C. Majure
Paul McKenzie
Conley K. McMullen
John McNeill
Nicole Miller-Struttmann
Wayne Morris
Howard S. Neufeld
Priscilla Nyamai
Michael W. Palmer
Derick B. Poindexter
Christopher P. Randle
Donald G. Ruch
Tom Saladyga
Michael Schafale
Gerald F. Schneider
Alfred Schotz
Scott Schuette
Victor Shelburne
Michael Simanonok
Mark Skinner
R. Wayne Tyndall
Donald Walker
Lisa Wallace
Thomas R. Wentworth
Alan Windham
Theo Witsell
George Yatskievych

Review of:
Chafin, Linda G., Author, and Hugh and Carol Nourse, Chief Photographers. 2016. Field Guide to the Wildflowers of Georgia and Surrounding States.
The University of Georgia
Press, Athens, Georgia.
516 p. Softbound. $32.95.
ISBN 9780820348681.

Significance. This is the first report of Hydrocotyle bowlesioides for North Carolina, expanding the range of the species to five states in the continental United States: Florida, Georgia, Louisiana, South Carolina, and North Carolina.

Hexastylis arifolia (Michx.) Small var. arifolia
(ARISTOLOCHIACEAE)—Shelby County

ABSTRACT: Changes in landscape spatial structure—specifically, reductions in habitat area and connectivity—are thought to be a primary cause of pollinator declines across North America. However, the mechanisms by which landscape structure influences pollinator diversity are not well understood. Because flowering plants and pollinators are generally mutualistic, the impact of landscape structure on one can influence the diversity of the other directly or indirectly. Here, we examine the direct and indirect effects of landscape structure on plant and pollinator communities in the naturally patchy, dolomite glade grasslands of the Missouri Ozarks. We quantified landscape spatial structure and the richness of plants and flying invertebrate pollinators in 30 glades. Higher pollinator diversity was not directly related to greater landscape area and connectivity. However, we found evidence for an indirect relationship where better-connected landscapes support higher plant richness, which in turn supports greater pollinator diversity. Our findings highlight the importance of conserving extensive, well-connected natural habitat in order to maintain the plant diversity needed to support diverse pollinator communities.

ABSTRACT Opuntia cespitosa (until recent taxonomic splitting, identified as O. humifusa) is an endangered cactus in Canada, is found in only two populations nationwide after some local extirpations. The larger site is at Point Pelee National Park (PPNP-ON) at the northern edge of its range has little published data. Data were collected for plant size, overlying cover (the species is sensitive to high shade), reproductive variables, and various cladode (pad) characteristics to assess response to local conditions. The PPNP-ON population was considered conspecific to many populations throughout the eastern USA until recently. A southern Humifusa clade population in Florida was sampled to confirm the recent separation of these populations into distinct species. A variety of parametric (e.g., ANOVA) and nonparametric (chi-square, Spearman’s correlation) tests were used to determine relationships across variables. This study contributes to our foundational knowledge of an endangered species. Results for this species in its last major Canadian population include that site conditions affect variables such as etiolation, in addition to shade. Plants are taller and have larger pads in Florida, supporting an upcoming taxonomic revision which would split the Floridian populations from the Ontario plants. Past work also suggests that Opuntia pads develop phototropically to maximize PAR (photosynthetically active radiation) receipt. Results show that while pads are statistically more parallel than perpendicular to the pad from which they grow, the offset is random. Thus physiological limitation of orientation is possible, or if there is a phototropic response, it occurs at the pad/areole scale.

ABSTRACT The ectomycorrhizal fungi associated with American chestnut (Castanea dentata) were characterized using DNA extracted from the root-tips of naturally occurring saplings from a forest in northeastern Tennessee. A total of 18 taxa were recorded, although one of these (Oidiodendron maius) was surprising because it has been reported previously to form what appear to be mycorrhizal associations only with members of the Ericaceae. One-third of the recorded taxa were representatives of the genera Russula or Lactarius (both members of the family Russulaceae), and three other genera (Cortinarius, Tomentella, and Tricholoma, each represented by two species). The data presented herein at least suggest that members of the Russulaceae are among the most common and widespread ectomycorrhizal fungi associated with naturally occurring individuals of American chestnut in the forests of eastern North America in which it was once dominant. However, it should be pointed out that our data are limited and thus are best considered as preliminary.