Illinois Native Plant Guide - Introduction and Purpose

Illinois Native Plant Guide

Introduction and Purpose

In order to gain the most benefit from the concepts and information presented in this Guide, users must understand the purpose of the Guide and its limitations and must consider the detailed species-specific information. It is important to emphasize at the outset that this Guide is intended to encourage the use of native plant species along streams and in and around stormwater facilities instead of traditional landscaping. It is NOT intended for wetland or prairie restorations or creations, particularly those restorations or creations implemented as part of a Clean Water Act permitted mitigation plan.

Increased urban development in northeastern Illinois has resulted in major changes in the area’s hydrologic regime. Presettlement information indicates that only a small percentage of precipitation in a given watershed actually resulted in measurable runoff. In the presettlement landscape, most precipitation was able to infiltrate into the soil. Today, streams which originally meandered have been straightened and channelized to carry larger flows. Stormwater detention basins are utilized to temporarily store excess stormwater generated by impervious surfaces and compacted lawns, as well as displaced floodplains and wetlands. Erosion commonly occurs along streambanks and edges of detention basins as a result of increased stormwater discharges and large fluctuations in water levels.

Traditional methods to control erosion and stormwater management problems have included structural measures such as rock and concrete structures, rip-rap, seawalls, and nonnative plant materials, such as reed canary grass and Kentucky bluegrass. In northeastern Illinois and elsewhere, there is a growing interest in the use of native plants to landscape and stabilize these areas. This approach, recommended or required by many natural resource and regulatory agencies, takes advantage of the deep-rooted native species that historically stabilized the soil, slowed runoff, facilitated infiltration, and decreased erosion prior to development of the area. These species may also offer a more aesthetically pleasing solution to the stormwater and erosion challenges of an urban area, while providing better wildlife habitat.

Native plantings can also provide economic benefits. The “bottom line” can be a strong motivation for installing and maintaining natural landscaping instead of conventional turfgrass. The major savings is in the lower cost of landscape maintenance. Over a ten year period, the combined costs of installation and maintenance for natural landscapes may be one-fifth of the costs for conventional landscape maintenance.

Using native vegetation along streams and in and around stormwater facilities also provides water quality benefits. Pollutants in stormwater can be removed by native vegetation through a combination of mechanisms. Physical, biological, and chemical pollutant removal mechanisms are documented to occur in wetlands and other natural communities. These mechanisms include nutrient uptake, sedimentation, adsorption, precipitation and dissolution, filtration, biochemical interactions, volatilization, and infiltration. More detailed information can be found in Strecker, et al. (1992), Adamus, et al. (1987), and others. In addition, the processes that occur in natural wetlands, which we try to emulate in stormwater management facilities, are described in Mitsch and Gosselink (1993), Galatowitsch and van der Valk (1994), Marble (1992), Hammer (1992), and van der Valk (1989). The reader who wishes to pursue a more complete wetland restoration is referred to these five referenced publications for more detailed and comprehensive information. For prairie restorations, Packard and Mutel (1997) is recommended reading.

There are 1,638 native taxa (species or subspecies) of plants found in the Chicago region (Swink and Wilhelm 1994). Native plants are those that are believed to have grown naturally in this region prior to settlement by Europeans. An additional 892 taxa grow naturally but are believed to have been introduced by settlers from other parts of the world. Current ecological understandings indicate that many of these introduced species displace native species and reduce diversity. Of the 2,530 types of plants known in the Chicago region, more than one-third were not here prior to European settlement. Yet out of the nearly 900 nonnative species, only about 150 species are generally successful and persistent. These 150 nonnative species dominate more than 95 percent of the vegetated landscape. Most human disturbed or managed landscapes are nearly monocultures, vegetated by only one or a few species. A natural prairie remnant, in contrast, can contain more than 100 species within just two or three acres. This mix of more than 100 species is what is meant by diversity, and is one example of biodiversity. Thus, using native species in stormwater management facilities and for streambank and shoreline stabilization can help increase biodiversity while providing a more aesthetically pleasing landscape. The more diverse native landscapes will be able to withstand more adverse conditions, such as droughts.

Currently, there are no other comprehensive guides that provide information on native species for streams and stormwater facilities in northeastern Illinois. This Guide will provide a valuable new tool for federal, state, and local governments, park districts, developers, landscape architects, engineers, homeowners’ associations, and others. While the science of using native plants in urban landscapes is expanding rapidly, much remains to be learned about most aspects of native landscaping in stormwater management facilities and streambank stabilization projects. With each project and with each native landscape restoration in the northeastern Illinois region, information about plant “preferences” and tolerances is obtained. Surprisingly little of this new knowledge is published and that which is, remains difficult for nonscientists to access and apply.

This Guide is an effort to consolidate the information available from as many different sources as possible. It also relies heavily on the knowledge and experience of local restoration ecologists and practitioners. This knowledge and experience encompasses a large amount of information that is not published and is generally not available to those from other disciplines or vocations. The information in this Guide is intended primarily for use in stormwater management facilities and streambank stabilization projects. Wetland or prairie restorations or mitigation required under Section 404 of the Clean Water Act will likely need to go beyond the species and information in this Guide. True prairie and wetland restorations will not be constrained by detention or other goals and purposes and should include more diverse species communities. The species selected for inclusion in this Guide are thought to be more tolerant of the harsh urban environment, relative to other more sensitive native species. Species in this Guide are also more easily established and widely available.

This Guide provides practical information in a user-friendly format and will guide the selection and placement of native species in those areas where they can best compete and survive. Individual species are presented on facing pages with several categories of information given for each. Some species were included even if all the information required in a given category was not available. Suggested mixes or lists of species for different applications are also suggested. If users of this Guide have experience or literature references that would add to the information contained herein, this information with references should be sent to: USDA Natural Resources Conservation Service’s Chicago Metro Urban and Community Assistance Office, 603 E. Diehl Road, Suite #131, Naperville, Illinois 60563 or U.S. Fish and Wildlife Service, Chicago Field Office, 1000 Hart Road, Suite 180, Barrington, IL 60010 for possible inclusion in future editions.