Pam Larsen explains what volatile organic compounds are and how they can provide their own defense against pests at noon on Thursday, Sept. 8, in the County Commissioners meeting room at the Clallam County Courthouse, 223 E. Fourth St., Port Angeles.

The presentation is part of the “Green Thumb Garden Tips” brown bag series sponsored by the WSU Clallam County Master Gardeners.

According to Larsen, plants have survived for hundreds of millions of years in part because of the release of gaseous messages, the volatile organic compounds. These messages are understood by nearby plants and insects, warning other plants of potential attack by herbivores or requesting more mobile members of their neighborhoods to come to the aid of plants under herbivore assault.

This program introduces gardeners to some of these amazing relationships and help explain how plants did so well before people added pesticides to the garden picture.

A long-time organic gardener, Larsen has taught organic gardening classes for The Community Gardens of Sequim for eight years and for the general public. For the past four years she has been working on ways to translate technical scientific research on this topic into gardeners’ language.

She has a proposal for an article on “The Volatile Language of Plants” accepted by American Gardener, a publication of the American Horticultural Society, and hopes someday to organize the research she’s accumulated into a book for gardeners.

The Master Gardener Brown Bag series continues on the second and fourth Thursday of each month. Presentations are from noon-1 p.m. For more information, call 417-2279.