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Peter Alden The Plants Henry Never Knew: The Invasive, Alien Plant “Crisis” with Peter Alden

Learn about locally invasive plants, where they came from, what we are doing (or not doing) and what Henry would think.

Henry David Thoreau was a fine observer and recorder of wildlife and plants in the mid-1800’s. As a botanist, he was both a collector and an early phenologist, noting the times of flowering, leafing, and fruiting over decades. Now, 175 years later, Henry would be fascinated (and shocked) to see what grows in our woods, fields, marshes, rivers and back yards. Sauntering around Concord at growing season he would find a quarter of the species he studied missing. He would note native flowers coming out earlier and breeding summertime birds arriving earlier. What might draw his attention most is the abundance of trees, shrubs, vines, wild flowers, grasses and aquatic plants that he would not recognize.

This presentation of charming newcomers (and the birds and people that spread them) will prepare you for next summer’s gardening fun.

Peter Alden is a Concord author and naturalist. He has spent 55 years leading birders and travelers to over 100 countries on the seven continents and the seven seas. He is the author of more than 15 books on North American and African wildlife, including the National Audubon Society’s Regional Field Guide Series and has sold over 3 million copies. On July 4, 1998—a date commemorating the 153rd anniversary of the day Thoreau moved into the cabin he had built at Walden Pond—Peter and the late Dr. E.O. Wilson organized the world’s first bioblitzes centered at Walden and supported by the Walden Woods Project, Minuteman National Park and National Geographic Society. Hundreds of invited specialist field biologists have verified 3,600 species of vertebrates, invertebrates, plants, mosses, lichen and fungi in 3 days! He serves on the Thoreau Farm Trust board of directors and is part-time at the Thoreau Society Shop at Walden Pond.


Jan 25 2022


7:00 pm - 9:00 pm

The Thoreau Society Bulletin is a 20-page newsletter with bibliographic information and writings on the life, works, and legacy of Henry Thoreau.

Each issue features news, upcoming events, and announcements from the Society, along with original short articles on new discoveries in and about the world of Thoreau, his contemporaries and related topics. It also contains a Notes & Queries section and a President’s Column, as well as additions to the Thoreau Bibliography and reviews of new literature relevant to the field. Edited by Brent Ranalli.

The Thoreau Society Bulletin is mailed to each member on a quarterly basis as a benefit of membership.

Membership includes a subscription to the annual journal.


The Concord Saunterer is a valuable aid to studies of Thoreau.” — Harold Bloom, Yale University

The Concord Saunterer: A Journal of Thoreau Studies is an annual peer-reviewed journal of Thoreau scholarship that features in-depth essays about Thoreau, his times and his contemporaries, and his influence today. Membership includes a subscription to the annual journal.


Get news from the Thoreau Society and learn about ways you can help preserve Thoreau Country as part of our common heritage and as the embodiment of Thoreau’s landmark contributions to social, political, and environmental thought.

The Thoreau Society®, Inc.
341 Virginia Road, Concord, MA 01742
P: (978) 369-5310
F: (978) 369-5382

Educating people about the life, works, and legacy of Henry David Thoreau, challenging all to live a deliberate, considered life—since 1941.


Any views, findings, conclusions, or recommendations expressed in this article do not necessarily represent those of the National Endowment for the Humanities.

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