Bringing Nature Home: How You Can Sustain Wildlife with Native Plants / Douglas W. Tallamy -- Portland, OR: Timber Press, 2007

I've known more than a few wags who have remarked slyly that a weed is simply a plant that you don't want, and while that initially seems generous and open minded with respect to the natural world, it misses the critical role that some plants play in their ecosystem and the role that others don't play. From the perspective of a healthy, diverse, and functioning ecosystem, some plants (weeds) simply don't pull their weight, while others are citizens in good standing. In the first half of Bringing Nature Home, Douglas Tallamy brilliantly argues that plants in good standing are, generally speaking, native to the region, while non-natives tend in almost every case to be either unhelpful or positive threats to the diversity of life. What Tallamy hopes the reader will take home from this is that converting your garden to a native plant preserve is one of the easiest ways a gardener can help recover the ecosystem that is most beneficial to his or her locale.

The key element in the overall picture is the insect population. Gardeners often treat insects as the enemy and in some cases they can be; however, in a well-functioning ecosystem herbivorous insects are a critical link in the food chain linking plants to larger, more charismatic animals, like birds, frogs, rabbits, and turtles. Non-native plants have become best-sellers in nurseries all over the country in large part because they are "insect resistant," meaning, they aren't food for anything in the ecosystem. Planting such species is comparable to laying down astroturf, planting plastic flowers, and erecting artificial trees. They may look nice and be generally whole and intact, but they serve no other purpose but to decorate one's garden. Worse, they have a tendency to spread out of control and take up an enormous amount of space, crowding out ecologically valuable species. Of course, the loss of habitat for insects results in a loss of habitat for larger animals. After reading Tallamy's arguments, one comes to appreciate the beauty of the ragged shape of an insect-eaten leaf. One's heart goes out to noble native plants that has given up some portion of their foliage for the greater good of the ecosystem.

One of the most significant environmental problems we face today is the loss of habitat. Urban sprawl and mono-cultural fence-to-fence agribusiness farming has left less and less room for inhabitants of the natural world and is drastically reducing the size of numerous species' populations. Tallamy argues that urban and suburban gardeners can do quite a lot to mitigate this problem simply by choosing to plant natives in their gardens. One small suburban lot may not seem like a significant contribution to the solution, but if gardening with natives becomes as popular as gardening with non-natives, the problem will be cut in half.

A yet stronger response to the urban-suburban desert-scape that we have created would be to organize whole neighborhood or cities to plant native plants. Recent ecological research shows that the size of a contiguous ecosystem is important to maintaining a native wildlife population. This runs counter to the belief that many small fragments of an ecosystem can effectively support the population. Obviously, fragments suitably close and with no significant barriers can be helpful, but organizing large swaths of natural habitat is preferable. Still, to get to this stage, pioneer native gardeners are critical. Happily, Tallamy provides tips on "making it happen."

The second half of Bringing Nature Home is essentially a reference guide to useful native plants and insects, a.k.a., "bird food." Tallamy also provides a valuable chapter entitled "Answers to Tough Questions," like "If birds eat the berries of alien plants..., why shouldn't I plant those species?" (The short answer is that those berries do not provide adequate nutrients required to make eggs, to feed the parent birds while they are feeding the young, and to feed the young themselves. Too many such plants means there will be fewer insects to provide the nutrition needed for reproduction.)

Finally, there are three excellent indexes listing native plants across the U.S., host plants for specific butterflies, and results from experiments comparing the value of native and non-native plants. Also there are numerous beautiful color photographs and a superb bibliography.

No gardener interested in native plants should be without this book!

Native Plants for Wildlife Habitat & Conservation Landscaping-Chesapeake Bay Watershed / Britt Slattery, et al -- MD: US Fish & Wildlife Service, 2003

There are a lot of very good reasons to remove invasive plants -- particularly non-native invasives -- and replace them with less aggressive native plants. Most important is the ability of a variety of native plants to support the local wildlife, but also important is their ability to improve the soil quality by sinking deep roots that aerate the top soil and add organic matter. Deep rooted plants are also far better at retaining water and in urban and suburban areas, this is critical for reducing the destructive, polluting, storm water runoff that is killing our streams rivers, and bays.

However, identifying the right native plant is not always easy. Fortunately for those of us who live in the Chesapeake Bay watershed, the U.S. Fish and Wildlife Service has published a handy catalog of hundreds of native plants: ferns, grasses, herbaceous plants, herbaceous emergents, shrubs, and trees. For each (or almost each) plant, the guide provides basic information to help you decide if the plant is right for you.

The guide identifies the basic characteristics of the plant: size, colors of its flowers, leaves, and fruit, as well as the time of the year when it flowers and fruits. It also provides basic information about its optimal growth conditions: sun, shade, and partial shade; but also soil pH and soil conditions: clay, loam, sand, or organic. It even provides an indication of the ideal habitat and geographic region within the watershed to help ensure that its nativity is reasonably local. For anyone particularly interested in attracting wildlife to your garden, it indicates how attractive the plant is to song birds, water fowl, small mammals, butterflies, beneficial insects, and hummingbirds.

The authors point out, of course, that the Chesapeake Bay contains many more native plants than are included in this catalog, and encourage the reader to seek out other sources to learn about those plants outside of their selection. The encouragement isn't necessary, though, as one's appetite for more information about native plants is whetted by the guide's clear presentation alone.

Perhaps the only weakness is the size of the photographs. While it is great to have photos of each plant, the photos are tiny and there is only one (sometimes two) for each plant, sometimes showing fruit, leaves, or blossoms, but seldom more than one of the characteristics. Consequently, using the book in conjunction with other reference sources amplifies its value, but regardless of this drawback, it is an extremely helpful starting point for learning about what native plants will grow well in your garden.

Wild Urban Plants of the Northeast: A Field Guide / Peter Del Tredici -- Ithaca: Cornell University Press, 2010

For at least a century, American botanists have raised the alarm over the invasion of non-native plant species. The immigration to North America of people from all over the world has brought with it food crops, ornamental plants, and stow-away seeds that have found a congenial new habitat in the Americas. The primary concern is that these non-native species are sometimes "invasive," meaning they exist without natural predators and therefore spread out of control. Their success crowds out many native species, thus reducing the diversity of the native ecosystem and damaging the health of the environment.

Despite the apparent threats, Peter Del Tredici, Senior Research Scientist at the Arnold Arboretum at Harvard University, is not so alarmed about non-native invasives. Starting from the premise that our native ecosystem has been irreparably transformed by urban development, native species are now as alien to the new urban ecosystem as non-natives. For Del Tredici, the important question in the urban setting is not whether the plant thrived in a by-gone local ecosystem, but whether the plant provides "ecosystem services" that would not otherwise be provided to the city.

In place of the native/non-native distinction, Del Tredici distinguishes plants that grow spontaneously in the urban environment versus plants that require cultivation. In the concrete jungle, Ailanthus altissima (the tree-of-heaven) is able to grow without any help from us, and according to Del Tredici, without this species, our urban tree canopy would be greatly impoverished. Replacing them with "native" species and maintaining natives would require an enormous effort for little or no increased benefit. Among the ecological benefits that spontaneous plants can provide to the city are temperature reduction, food and habitat for wildlife, erosion control, riparian stabilization, nutrient absorption, soil building, and phytoremediation or the ability to absorb and store heavy metals thereby cleaning contaminated sites.

Del Tredici's argument is persuasive, but only as long as we accept that our urban environments will be built without caring that they be hospitable to formerly native species. Careful urban planning can increase the areas that are compatible with native plants and thereby preserve the local biological heritage. Del Tredici would, however, point out that this reflects a cultural value judgement and can not be defended on the basis of biodiversity or ecological services. On the other hand, invasives are often able to spread rapidly outside of the urban environment and into relatively undisturbed ecosystems. Such escapees from the city likely pose all the threats to native species about which botanists warned us.

Del Tredici's argument in favor of spontaneous plants makes up just 23 of the book's 374 pages. The rest of the book is, as the subtitle states, a field guide in which spontaneous urban plants are cataloged and described in a manner traditional to such field guides. Each entry includes, however, information on the ecological functions and cultural significance of the plant described. This is consistent with Del Tredici's two primary goals, "to teach people how to identify the plants that are growing in urban areas, and to counter the widespread perception that these plants are ecologically harmful or useless and should be eliminated from the landscape." Each entry also includes five or six useful color photographs of the plant or its near cousins.

Guide to the Flora of Washington and Vicinity / Lester F. Ward -- Washington DC: GPO, 1881

Flora of Washington is a monograph in the series Bulletin of the United States National Museum, published by the Department of Interior under the direction of the Smithsonian Institute. It is the first "scientific" attempt to catalog the flora of Washington and the surrounding region since the 1830 catalog entitled Florae Columbianae Prodromus, and it contains lists of plants found by several botanists (mostly Ward) over the years 1878-1880.

The volume begins with 59 pages describing the range and localities where plants were collected with various information about the flowering of plants, their statistical frequency, and the methods for classifying them, but the heart and bulk of the volume is a list of the Latin names of the collected plants. Usually accompanying each entry is the name of the collector, the common name or names of the plant, the times when it flowers and fruits, and, when the plant is not commonly found in the region, the locale where it was found. Sometimes further information is included in a note.

Ward's list of plants includes an indication as to whether the plant appeared on the 1830 Prodromus list, providing a valuable record of the impact of the growth of the Washington D.C. on the flora of the region. Unfortunately, the method of classifying plants has changed since 1881, making current use of the list difficult. However, many names are consistent with our names today. For example, Ward writes that Cannabis sativa grows in "waste lots in the city." Somethings haven't changed. Throughout the work, many current concerns about invasive species and habitat destruction are raised, though the concern is understandably less critical than it is today.

The final 28 pages are "Suggestions to Beginners," explaining in extraordinary detail the equipment needed to identify, collect, transport, preserve, and mount plants to be included in one's herbarium. Ward even recommends methods for mailing one's plant inventories and duplicate plants to other botanists when making trades. (By including nothing in writing in the packages of plants, one could take advantage of a cheaper postal rate.)

Flora of Washington contains a final gem: a 31" x 24" fold out map of the Washington D.C. region, printed in 1882. The region ranges from the Rockville and Laurel post offices in the north to the confluence of the Occaquan and Potomac Rivers in the south; and from the Bull Run post office in the west to the Patuxent River in the east. Along with the river system of the region, roads also appear on the map. Some have retained their names to the present, others have changed, but hardly any follow the same routes of their descendant roads today.