An illustrated flora of the northern United States, Canada and the British possesions from Newfoundland to the parallel of the southern boundary of Virginia and from the Atlantic Ocean westward to the 102d meridian. Vol. 3, Apocynaceae to Compositae, dogbane to thistle
Britton, Nathaniel Lord,
Frodin 2 : 140.
Marquand, Eleanor: Library.
Fife, Sarah Gildersleeve : Library.