1. Leaves densely soft-pilose, the blades less than twice as long as broad; achenes black; bracts about equaling or shorter than the flowers; anthers ca. 1 mm long.

P. judaica

1. Leaves glabrous to only sparsely and minutely pilose, the blades mostly at least (2.5-) 4-6 times as long as broad; achenes pale whitish to brown; bracts much exceeding the flowers; anthers less than 0.5 mm long.

P. pensylvanica