Rarity Status Assessments of Bugseeds (Amaranthaceae: Corispermum) in Manitoba

Abstract

To provide a more accurate assessment of the rarity of the plant genus Corispermum (Amaranthaceae), commonly known as bugseeds, in Manitoba, I undertook a survey of all historical populations. In total, 68 quarter sections were selected for presence/absence surveys; 37 of them contained at least one species of bugseed. Only 10 of the 20 historical populations in Manitoba were relocated. The total estimated size of known bugseed populations in Manitoba in 2010-2011 was approximately 9,820 to 13,060 individuals. American Bugseed (C. americanum (Nutt.) Nutt. var. americanum) is the most abundant and widespread of the bugseeds in Manitoba, followed by Hairy Bugseed (C. villosum Rydb.). There is only one population of Hooker’s Bugseed (C. hookeri Mosyakin var. hookeri) in the province. Pallas’ Bugseed (C. pallasii Steven) was not relocated and should probably be considered extirpated in Manitoba. The habitats at 61% of the localities where bugseeds were confirmed are anthropogenically disturbed, the most common habitat being roadsides with exposed bare sand. Of the localities where bugseeds were not relocated, 67% occurred in natural sandy areas, suggesting that dune stabilization is a major threat to the continuing persistence of these species.