Hooded Arrowhead (Sagittaria calycina Engelm.)

The USDA PLANTS treatment lists two varieties of this species, var. calycina and var. spongiosa. However, most authorities including BONAP, POWO, and Go Botany, have split var. spongiosa into its own species. However, these authorities refer to it by different names, reflecting lumping that variety or those populations into different species. POWO treats it as a separate species, Sagittaria spongiosa (Engelm.) Werier, a treatment we adopt. BONAP refers to it as Sagittaria spathulata, and Go Botany refers to it as Sagittaria montevidensis.