Distribution and status of Howell’s Quillwort (Isoetes howellii, Isoetaceae) in Canada and its relation to Bolander’s Quillwort (Isoetes bolanderi)

Abstract

The sparsely documented lycophyte, Howell’s Quillwort (Isoetes howellii), occurs in Canada in four distinct areas of British Columbia in a variety of microhabitats. Before 2010, two areas of occurrence were known in Canada. Two additional clusters of occurrences have been discovered in the last decade. In Canada, I. howellii is found in open, ephemeral wet swales, shallow ponds, and periodically flooded shorelines, channels, and back beach meadows. Habitat rarity may be the primary reason for the large gaps between areas of occurrence. The current viability of the Canadian population is dependent on maintaining the recently discovered large number of individuals in the North Thompson River Region. Isoetes howellii shares many similarities with fellow diploid, Bolander’s Quillwort (Isoetes bolanderi). The possibility that it represents a low-elevation subspecies of I. bolanderi requires further investigation. Isoetes howellii is rare in British Columbia and warrants consideration as a species at risk in Canada.