Episodes of the cult television series "Twin Peaks" (1990-91) featured monologues with the enigmatic Log Lady, played to deadpan perfection by actress Catherine Coulson. She would cradle a cut of Ponderosa pine like a baby, channeling its koans. As a forester, biologist and ecological activist, Suzanne Simard is a real-life tree whisperer, and the trees whisper back. "Finding the Mother Tree" — a luminous weave of memoir, scientific treatise and Native-inflected meditation — is her singular story, rooted in keen observation and leaps of imagination.

Raised in rural British Columbia, Simard spent childhood summers among old-growth forests and craggy mountains. She limns her tale with rich anecdotes and family lore: a beagle trapped in an outhouse; a grandmother who would dance-step across logs in the Shuswap River. In one scalp-tingling scene, her cowboy brother is thrown by a bull, reminiscent of Annie Proulx's magnificent short story "The Mud Below." These are among the book's many writerly treasures.

But the science here is equally absorbing. Simard is foremost a student of trees. Early on, she stumbles across a vital linkage between forests and mycorrhizal fungi, and she devotes years of graduate study and creative field experiments to the complex symbiosis between overstory (the uppermost canopy) and understory (the saplings and shrubs below).

In the 1990s, this was a revolutionary insight. She even dabbles in radioactivity: "I could tell not only if carbon was passing from birch to fir but also distinguish if it was moving in the opposite direction, fir to birch, like trucks on a two-lane highway. By measuring how much of each isotope ended up in each seedling … I would know if trees were in a more sophisticated tango than just a competition for light."

Outside the silos of academia, Simard relied on her own intuition as she mapped out her ideas. She patiently waited for epiphanies: "My wrist lifted slightly in an upbeat, and my Geiger counter wand crackled faintly. … Strings and woodwinds, brass and percussion, exploding as one, flooding my ears, the movement allegro and intense … the breeze sifting the crowns of my little birches and firs and cedars seem to lift me clear up. … We were listening to birch communicate with fir."

Simard rejected the forest industry's clear-cutting and turned increasingly toward environmental advocacy. She swallowed her fear of public speaking. She published groundbreaking papers on how plants of all kinds send chemical signals to each other — a "wood-wide web."

And yet "Finding the Mother Tree" is never self-congratulatory; she exposes her darker moments with the same fortitude as she delves into her data. Her self-deprecating wit brings us into the messy human life of a brilliant mind.

For his Pulitzer Prize-winning novel "The Overstory," Richard Powers modeled a character on Simard; and indeed her book reads like a nonfiction cousin of his novel and Proulx's "Barkskins."

"Finding the Mother Tree" is a literary revelation, that botany class you never knew you needed, and certain to be one of this year's most widely discussed books.

Hamilton Cain reviews for a range of venues, including the Star Tribune, Oprah Daily, the New York Times Book Review, the Washington Post and the Boston Globe. He lives in Brooklyn.

Finding the Mother Tree
By: Suzanne Simard.
Publisher: Alfred A. Knopf, 368 pages, $28.95.