"An Orchard Invisible" plants seeds that sustain us

"An Orchard Invisible: A Natural History of Seeds"

by Jonathan Silvertown

University of Chicago Press, 224 pp., $25

In his new book, "An Orchard Invisible," ecologist Jonathan Silvertown begins with a Welsh proverb, from which his book takes its title: "A seed hidden in the heart of an apple is an orchard invisible."

Likewise, from a single idea — a natural history of seeds — emerges an enthralling study of the ways seeds survive in the terrestrial world, and also sustain us humans.

Silvertown approaches his subject, these "embryo[s] in a picnic basket," from various angles, among them sexuality, pollination, dispersal, germination, predators and diseases, and the use of seeds, in all their glory, in gastronomy.

The early chapters delve into the evolution and genetics of plant reproduction, kind of a slog for us science-challenged readers — some illustrations might have helped — but the author does season the science with an engaging, conversational style, and the backgrounding well informs the rest of the book.

The theme emerging here is the delicate pas de deux between plant and environment. For example, there's the largest seed in the world: the 45-pound, "double-coconut" fruit of the coco de mer palm, on two small islands in the Seychelles. Why so big? It seems the coconut, after falling beneath its sun-blocking mother palm, sends out an underground, 30-foot-long rope, at the end of which the seedling sprouts in sunnier climes.

Then there is the common gray squirrel, which nibbles the tip of an acorn to destroy the seed's embryo, thus keeping it from germinating and assuring a food source when the acorn is later dug up. Certain oaks, however, respond by producing an acorn with a displaced embryo to keep it from harm.

Silvertown ascribes nothing more to this process than natural selection, but his book will clearly remind its audience of a more vibrant, more sentient world than they might have imagined just outside their door.