Читать книгу The Midwestern Native Garden - Charlotte Adelman - Страница 8

HOW TO USE THIS BOOK

Midwest gardening focuses on changing seasons, so this book is divided into chapters covering spring, summer, fall, and winter, with some inevitable overlapping between the seasons. Each section contains a seasonal selection of alphabetically listed introduced (that is, nonnative, alien, exotic) garden flowers and plants that are popular in the Midwest. We list each plant and flower by its common name(s), followed by the family, genus, and species. Then we state its origin, which is frequently Asia or Europe. Next, we present the plant’s height, notable ornamental features (flower color, leaf shape), and cultivation requirements. An invasiveness note is provided if U.S. Department of Agriculture (USDA) maps or other resources indicate that the plant has naturalized or become invasive in the Midwest. Using “I” for “Introduced,” USDA maps reveal the great extent to which nonnative flowers and plants have moved into our Midwest ecosystems. USDA maps also document the Midwest’s threatened, endangered, rare, and extirpated native plants. Please reference USDA Plants at http://plants.usda.gov/.

Selecting the most popular nonnative plants turned out to be an eye-opener. The choices offered by most national nursery outlets, mail-order catalogs, large local nurseries, supermarkets, and garden centers are usually between one nonnative plant and another nonnative plant. Because mainstream sellers rarely offer native plants, it is no wonder imported plants dominate our gardens and landscapes and that we see fewer butterflies. In response to the increasing interest in native flora, some mainstream plant businesses include a few popular native plants. Though these offerings are usually hybrids or cultivars, popular demand is creating better choices. As customers we should ask sellers to offer native plants.

Following each nonnative entry is the heart of this book: descriptions of regionally native midwestern plants and flowers that resemble the nonnative plant in height, notable ornamental features (flower color, leaf shape), and cultivation requirements. The term “native midwestern plants” means plants that occur naturally in this region and were not introduced by direct or indirect human actions. These days it is easy to obtain native flowers, shrubs, trees, and grasses from the many native plant nurseries that sprung up in response to the needs of today’s buying public. In addition to native plant mail-order catalogs, Web-based native plant catalogs, local native plant nurseries, and native plant landscapers there are native plant sales run by park districts, forest preserves, community organizations, and native plant associations. Following each native plant entry we present a nature note, referencing some of the connections between a native plant and wildlife, especially butterflies and other native insects, because most native insects lay their eggs on native plants, which they require for successful reproduction.

Some plants in this book may be familiar under other common or botanical names. We often list several common names for nonnative plants and native alternatives (later references to the plant use only the first common name listed). But a plant’s botanical name is its only positive identification. This is why its botanical name should be verified before making a purchase or before incorporating plants provided by a neighbor or a friend. Occasionally even botanical names change, so if one doesn’t ring a bell, check its current status. For example, due to reclassifications of an American genus, Symphyotrichum is increasingly used instead of Aster. For butterflies, common and taxonomic names have changed significantly, and some quite recently, over the past century.

Our focus on native plants in the Midwest, an admittedly broad and imprecise region, is complicated by the existence of varying definitions, categories, and climate zones. We include Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, Wisconsin, and Ontario, Canada, in accordance with the Midwest Invasive Plant Network’s (MIPN) view of the region; here gardening practices are similar. However, our suggestions for native plants apply to most states that are adjacent to those set forth above.

USDA Hardiness Zones Maps show ten different zones, each of which represents an area of winter hardiness for the plants in our natural landscape. However, there are many plants that share hardiness zones but are native to entirely different geographical locations and ecosystems. “Hardiness ratings alone are inadequate to guide landscapers in selecting the most successful plants,” states the United States National Arboretum.¹ That climate zones are changing is another consideration. For example, the USDA puts Chicago into Zone 5b, with the outlying areas falling into the slightly harsher Zone 5a. The Arbor Day Foundation’s updated hardiness map places the

Chicago lakefront and southern suburbs into the upper reaches of Zone 6.² Another way of analyzing the region to which a plant is native is by its plant province or regional vegetation type. The Midwest states we reference fall into the Eastern Broadleaf Forest Province or vegetation type.³

You can quickly determine whether a plant is native to North America, and to your state, by accessing USDA Plant Information.⁴ Enter the plant’s taxonomic name (or an accepted common name), and this will bring up the plant’s profile, with all its synonyms plus additional Web sites if available. A distribution map depicts the plant’s province, or natural distribution, and, if a nonnative plant, where it has become naturalized or invasive.

The Midwest is home to North America’s most dense monarch butterfly population. But these well-known insects are under threat from dwindling habitat and herbicides that kill the butterflies and the milkweed upon which larvae must feed and upon which the adults depend for food. Gardeners and landscapers who want to benefit the greatest number of butterflies should determine which butterflies are local to their area and garden with these butterflies’ “host plants.” Generally, regionally native flowers, trees, shrubs, grasses, and sedges are the host plants on which butterflies lay their eggs and that their caterpillars (or larvae) eat. Host plants also supply nectar and pollen to adult butterflies, bees, and hummingbirds. To determine whether a butterfly occurs in your area, Jeffrey S. Pippen of Duke University’s

Nicholas School of the Environment recommends accessing “Map Search,” at http://www.butterfliesandmoths.org.

Plant heights, bloom periods, and cultivation requirements can vary with a plant’s geographical location and because of differences in light, soil, and other environmental factors. This can give rise to different information from different sources. For the best results, discuss your garden’s specific requirements with the purveyor before you purchase a plant.

For additional information about native plants and their associated wildlife, check with your state and local bird, native plant, and lepidopterist (butterfly/moth) groups. Also access state departments of natural resources and transportation; natural history museums; botanical gardens; native plant, butterfly, and bird books (see bibliography); national groups; federal agencies; and purveyors of native plants (see “Selected Resources” in the bibliography).