About Idahoa scapigera (Hook.) A.Nelson & J.F.Macbr.
Idahoa is a monotypic genus of flowering plants in the mustard family (Brassicaceae), consisting of just one species: Idahoa scapigera (Hook.) A.Nelson & J.F.Macbr. This species has two common names: scalepod and oldstem idahoa. It is native to western North America, where its natural range extends from British Columbia in the north, through California to the south, to Montana in the east. It grows most commonly in mountain and foothill habitats. It is a small annual herb that forms a basal rosette of leaves. Each leaf has a petiole, is one to three centimeters long, and has smooth or lobed margins. It produces thin, leafless erect stems that reach a maximum height of around ten centimeters. Each stem holds just one tiny flower, which has white petals positioned above red-purple sepals. After flowering, the plant produces a fruit that is a flat, round capsule, shaped like a disc or slightly oval. This capsule is 6 to 12 millimeters wide. When young the fruit is green, and it dries to become papery and gray or white in color.
