Hannah Fries’s ‘A Forest Language’ – A Way to Garden with Margaret Roach – Sept. 28, 2026

Margaret Roach and author Hannah Fries spend an hour on Fries's new book A Forest Language, a glossary-style essay collection built around tree terminology. The trigger was a pair of earrings depicting "crown shyness," the phenomenon where neighboring tree crowns grow right up to each other's edges but stop short of overlapping.

The most practically useful distinction in the conversation: sap and pitch (resin) are not the same thing. Sap is mostly water, roughly 98% in maple, and moves upward through the xylem in spring. Pitch is sticky, chemically distinct, and functions as the tree's wound-sealing immune response. Fries notes that Norway spruce resin has been studied in wound-care research, though she presents it as an interesting data point, not a clinical recommendation.

On wood structure: sapwood is the living outer layer that moves nutrients; heartwood is the dense, often darker center made of cells that are no longer alive. A tree can lose its entire heartwood to rot and keep fruiting and leafing out, because sapwood handles all the transport. Roach says her old apple trees prove the point.

The one piece of advice worth keeping if you manage any garden or wooded land: before you have a dying tree taken down to the ground, ask your arborist whether cutting it at eight to ten feet instead would leave a functional snag. Standing dead wood is wildlife habitat and costs nothing extra to create. Fries and Roach both make this case, and it's sound.

The rest of the episode covers burls, gemels (the fused points where two branches or roots from separate trees grow into each other), thaw circles, nurse logs, and marcescence (the beech-and-oak habit of holding dried leaves through winter rather than dropping them in fall). Engaging nature talk. Nothing here touches a financial decision, a health choice, or a family situation.

Host Margaret Roach and author Hannah Fries’s’s’s’s’s’s discuss Fries's new book A Forest Language, a collection of short essays built around tree and forest vocabulary — words like "crown shyness," "marcescence," and "nurse log." The episode is a pleasant nature conversation with no money, health, or life-decision content of substance.

What was covered

• The book's origin: Hannah Fries’s’s’s’s’s’s describes how a pair of earrings depicting "crown shyness" — the phenomenon where neighboring tree crowns grow up to each other's edges but not over them — inspired her to write a glossary-style essay collection about tree terminology.
• Sap vs. pitch (resin): Sap is watery and liquid (maple sap is roughly 98% water), flowing upward through the xylem in spring; pitch or resin is sticky and serves as the tree's immune defense, with antimicrobial properties that Fries notes have been studied for wound-healing in humans (she mentions Norway spruce resin as one example).
• Heartwood vs. sapwood: Sapwood is the living outer wood carrying nutrients; heartwood is the dense, often darker center made of no longer living cells. Some species' heartwood is naturally rot-resistant, useful for fence posts. A tree can survive even after its heartwood rots away, leaving a hollow trunk — Roach notes her old apple trees demonstrate this.
• Burls, gemels, and thaw circles: Burls are knobby growths caused by disrupted cell growth after minor injury, prized by woodworkers for their swirled grain. Gemels (also called inoculations) are points where branches or roots of two separate trees fuse after repeated contact. Thaw circles are the rings of bare ground that appear around tree bases in late winter as dark bark absorbs sunlight.
• Nurse logs, snags, and forest succession: Fries and Roach discuss the ecological value of fallen logs (nurse logs) and standing dead trees (snags) as habitat and soil builders. Both advocate leaving aging trees in place where safety allows, and note that arborists can cut a hazard tree higher up to create a functional snag rather than removing it entirely.
• Marcescence: The term for leaves — common on beech and many oaks — that dry out and cling to branches through winter rather than dropping in autumn. Theories include protection of dormant buds from browsing animals and timed nutrient release to the soil just as the tree wakes in spring.

Notable claims & predictions

• Hannah Fries’s’s’s’s’s’s: Sap and pitch are often used interchangeably but are chemically distinct — sap is mostly water and flows; pitch is sticky and functions as a wound-sealing immune response.
• Fries: The antimicrobial properties trees use to defend themselves sometimes translate directly to human medicine; Norway spruce resin is one studied example of wound-healing application.
• Fries: A tree can remain fully alive and productive — fruiting, leafing out — after its entire heartwood has rotted away, because the outer sapwood handles all nutrient transport.
• Margaret Roach: Allowing dead wood to remain on the ground is not neglect but soil-building; without duff accumulation and decomposition, forest soil cannot regenerate.
• Fries: Naming something with precise language causes you to notice it more — the practical argument for why botanical vocabulary is worth learning.

Fact check

The claims in this episode are botanical and ecological rather than financial or medical. The statements about sap composition, heartwood/sapwood function, and forest ecology are consistent with standard dendrology and are not contested. The mention of Norway spruce resin having wound-healing properties is plausible — spruce resin-based preparations have been studied in wound care research — but Fries presents it as an interesting finding rather than a clinical recommendation, so no overclaim is made. No claims fail scrutiny.

Why this matters for you

• If you garden or manage any wooded land, the practical point worth keeping is the one about snags and nurse logs: before having a dying tree removed entirely, ask your arborist whether cutting it at 8–10 feet rather than at the base would leave usable wildlife habitat. It costs nothing extra and Roach and Fries both endorse it.
• The distinction between sap and resin is genuinely useful if you make maple syrup or work with conifers, but carries no health or financial consequence.
• The rest of the episode is engaging nature talk. There is nothing here that affects a financial decision, a health choice, or a family situation — interesting, but nothing to act on this week.