From a couple of spikes collected: achene l/w and "knobs" appear to match key; two single culmed plants present in area; woodland vernal pool edge; went out today (Sault) to get lupulina fruit to compare achenes... last images.
Odd growth form, giving off the impression of J. brachycephalus, but outer tepals acute. Nearly 60cm tall. In fen adjacent to lake/beaverpond with numerous other graminoids (Juncus pelocarpus, Juncus canadensis, "typical" Juncus brevicaudatus, Carex lasiocarpa, Eleocharis palustris, Dulichium arundinaceum etc.)