POWO and standard current floras of WA [Flora PNW 2], OR [OregonFlora], CA [Calflora and Jepson eFlora], and BC [eFlora BC] all synonymize A. amplexicaulis under A. lanceolata subsp. prima.

If anyone's interested, I've reviewed the taxonomic history on obs 68918654, but it shouldn't matter much. This seems fairly open and shut clerically, but I'll leave it open for someone else to commit.

@bouteloua @jdmore @eralverson @walterfertig