Berkeley Sedge is Eurasian Grey Sedge

A pot of the more loosely tufted foothill sedge (Carex tumulicola). Photographs by Dave Fross

Over the past fifteen years, emerald tussocks of Berkeley sedge have been so successfully established in West Coast gardens that many gardeners have affirmed its horticultural virtues and its role in helping connect their gardens to their native contexts. As a rapidly growing, nearly evergreen perennial for sun or shade, wet or dry soils, Berkeley sedge also tolerates trampling, and reproduces readily from seed in many gardens—all traits sought after in natives for gardens or wildland revegetation, but despised in alien weeds.

As the horticultural renown of Berkeley sedge grew, so did doubt about its species assignment to Carex tumulicola and provenance as a West Coast native. My suspicions arose over a decade ago after my attempts to confirm identity of some nursery stock did not lead to C. tumulicola, or to any other North American sedge. Others reached the same perplexing conclusion independently. Although the name Berkeley sedge presupposes that mother stock was obtained from native populations in the vicinit...