Environmental analogs in the search for stress-tolerant landscape plants

This paper reviews briefly the climatic and edaphic factors related to tree adaptation. Photoperiod regimens, the timing and severity of low temperatures, and high temperaturemoisture interactions all are important climatic determinants of adaptation for which adequate data have been widely recorded. Edaphic factors that injure trees in managed environments are more difficult to extrapolate to natural systems, but natural soils that are poorly drained, calcareous, alkaline, or saline may be initial foci for seeking tough trees. A project to identify promising new landscape plants for the north-central United States, by examining climatic, edaphic, and floristic factors in Eastern Europe, is presented as a case study

Short Term Pollen Storage of Two Rhododendron simsii Cultivars

Rhododendron breeders work with a genus that collectively has a broad flowering season. However, many individual species or cultivars flower for much shorter periods. To make many desirable crosses, it becomes necessary for the breeder to store pollen. Existing literature offers only brief recommendations on storage conditions in reports by Bowers (1932), Lee (1958), and Schroeder and Bump (1982) and a single, more detailed report by Visser (1955) that few breeders have available. This study outlines the relative value of a range of storage conditions for short-term (two weeks or less) pollen storage of two cultivars of evergreen azaleas. Long-term storage is generally done successfully by using variations of the desiccator-freezing method, as described by Schroeder and Bump (1982) and Visser (1955)

Building a comprehensive collection of Ash germplasm

This paper summarizes a presentation from the Congress Symposium, “The Introduction of the Emerald Ash Borer in North America, A Case Study of Invasive Species Epidemiology and Conservation of the Host Species.” It briefly discusses the state of Fraxinus (ash) taxonomy, ash as a landscape and forest tree, some of its specialized uses, including those by Native Americans, and its role in supporting other organisms. The devastation caused to native, North American ash populations by the introduction of Agrilus planipennis (emerald ash borer; EAB) to the Detroit, Michigan area has already led to the loss of tens of millions of trees. Diverse efforts are underway to document and slow EAB’s spread and develop appropriate biological controls. Scientific research on ash-EAB interactions, including the study of potential tolerance or resistance mechanisms, breeding and genetic-diversity analyses, and ash systematics, would all benefit from access to well-documented, diverse ash germplasm. To help redress this unfolding biological tragedy, a collaborative, international effort to conserve these important genetic resources has been organized. Fortunately, ash is amenable to ex situ conservation through seed storage and cryogenic storage of dormant winter buds. Key partners in this effort are described herein, with a focus on the coordinating organization, the USDA-Agricultural Research Service’s National Plant Germplasm System, along with a summary of progress to date and future plans

While They Were Asleep: Do Seeds After-Ripen in Cold Storage? Experiences With Calendula

Methods to break seed dormancy are of great interest to plant propagators, with many papers on this topic presented at past I.P.P.S. meetings. For example, in Vol. 54 of our Combined Proceedings of the International Plant Propagators’ Society, there were reports on embryo culture to avoid dormancy (Douglas, 2004) and recommendations on dormancy-breaking techniques for Helleborus (Bush, 2004), Salvia (Navarez, 2004), and many wildflowers and grasses native to the North Central U.S.A. (Diboll, 2004). As propagators, we typically want quick methods that consistently result in high germination rates without large labor inputs. But if we can afford to be more patient, some seeds may eliminate their primary dormancy mechanisms during storage. This progressive loss of dormancy after maturity in “air-dry” seeds is known as after-ripening (Murdoch and Ellis, 2000). Typically, after-ripening is thought to occur under warm, dry conditions (Foley, 2000; Probert, 2000), but the literature of after-ripening is somewhat confusing. Simpson (1990) defined after-ripening in a more general way as “loss of the dormant state over some period of time through exposure of the seeds to a set of environmental conditions after maturation and separation from the parent plant.” The term has even been used to describe combinations of warm storage and the effects of stratification (Baskin and Baskin, 1988)

The Genus Rubus L. in Iowa

Morphological features were examined from more than 5,000 Rubus specimens to prepare the first comprehensive revision of the native and naturalized Rubus of Iowa. Twenty-eight species (one with two varieties) and one interspecific hybrid have been collected in the state. They are described in this revision, which contains keys to subgenera and species designed specifically for field researchers in Iowa and nearby states. Synonymy, distribution, phenology, habitat, associated plants, and taxonomic treatment by past researchers are also discussed. Range-wide county distribution maps are presented for 22 species representing Rubus subgenus Rubus (the blackberries and dewberries), and Iowa county distribution maps have been included for R. idaeus L. var. strigosus (Michx.) Maxim., R. occidentalis L., R. parvifolius L., and R. pubescens Raf. The findings of this study are discussed in the context of the putative reticulate phylogeny among species of Rubus subgenus Rubus, and potential subjects for future molecular and cytological research are proposed

Insights Into Woody Plant Adaptation and Practical Applications

Since its inception in 1954, the NC7 Regional Ornamental Plant Trials have evaluated 623 different accessions of woody landscape plants under a wide range of environments across the North Central U.S. and at other locations with similar climatic conditions. The evaluation of replicated field plantings at multiple locations has a long tradition in forestry (Langlet, 1971; Wright, 1976) beginning with common-garden trials of tree populations in the 1700s and leading to the development of modern, replicated designs in Europe in the early 1900s. By evaluating many provenances of the same species at numerous sites, considerable knowledge has been accumulated about tree adaptation in relation to geographic origin and to climatic and edaphic conditions at the evaluation sites. This knowledge has been valuable in matching forest trees to appropriate production sites and has facilitated the breeding and selection of superior tree populations for timber and Christmas trees (Wright, 1976)

Seed storage for the commercial propagator

Commercial propagators routinely produce a diverse mix of seedlings, yet the volumes of the Proceedings of the International Plant Propagators\u27 Society have remarkably little advice on seed storage. Most propagators plant freshly-collected seeds or store seeds only briefly before planting. But there may be advantages to storing seeds for future use. This report will consider some of those advantages, summarize pertinent reports on seed storage for landscape plants, and present some personal experiences with germination of stored seeds

Old and New Trends Influencing the Introduction of New Nursery Crops

At the First National New Crops Symposium in 1988, I reported on four trends that were influencing the introduction of new landscape plants (Widrlechner 1990). These trends were: 1. increased interest in, and use of, low-input plantings; 2. edible landscaping; 3. in vitro propagation methods; and 4. ways to overcome limitations caused by urban conditions. But trends, by their very nature, are dynamic; what was timely twenty years ago can be passé today. The environment in which nursery producers and retailers operate continually evolves, and the trends that affect them and their consumers need periodic re-analysis. Thus, the objectives of this brief review are to examine how past trends have fared and to describe some trends that now supplant them or are poised to become more important

A Short Geography of Remembrance

In the early Summer of 2012, my wildest year came to a gradual close. To help mark that ending, through nearby friends I found a sweat lodge leader and learned the protocol for meeting him and requesting that a lodge be conducted on my behalf. This new collection of poems includes all the verses from eight of my chapbooks, beginning shortly after the sweat lodge and concluding as Summer began in 2013. As with the poems published in “This Wildest Year,” nearly all those included here have resulted from a spontaneous flow that still puzzles me. As you will soon see, the geography covered in these poems encompasses broad swaths of territory: physical and spiritual (or, in the Taoist sense, both earthly and heavenly). Occasionally, it also ventures into dreamscapes, especially in the closing chapter.https://lib.dr.iastate.edu/ebooks/1001/thumbnail.jp