Chamaenerion angustifolium (Linnaeus) Scopoli ssp. circumvagum (Mosquin) Moldenke. Phen: Jun-Sep. Hab: Grassy balds, roadsides, montane fields, burned areas, disturbed areas. Dist: Circumboreal, extending south in North America to NJ, montane w. NC and ne. TN, n. IN, MN, SD, AZ, NM, and CA.
Origin/Endemic status: Native
Taxonomy Comments: Chamaenerion angustifolium (in the broad sense) has a circumboreal distribution; it is composed of several related taxa that differ in chromosome number, a variety of morphological characters, and distribution. The tetraploid 'entity' is generally more southern, extending south in North America to NJ, montane w. NC and ne. TN, n. IN, MN, SD, AZ, NM, and CA; it has been variously treated at varietal, subspecific, and species rank (and under various generic names) as separate from Chamaenerion angustifolium sensu stricto. The diploid 'entity' is arctic and boreal, extending south in North America to NB, QC, ON, alpine WY, and BC. We here (relatively arbitrarily) employ subspecific rank for the tetraploid entity.
Synonymy: = FNA10, K3, K4, NY; = Chamaenerion danielsii (D.Löve) Czerep.; = Chamaenerion exaltatum Rydb.; = Chamaerion angustifolium ssp. circumvagum – Tn, misspelled; = Chamerion angustifolium (L.) Holub ssp. circumvagum (Mosquin) Kartesz – GrPl, K1, NE, Wagner, Hoch, & Raven (2007); = Chamerion platyphyllum (Daniels) Á.Löve & D.Löve – Va; = Epilobium angustifolium L. ssp. circumvagum Mosquin – Mosquin (1966); = Epilobium angustifolium L. var. canescens Alph.Wood – C; = Epilobium angustifolium L. var. platyphyllum (Daniels) Fernald – F; < Chamaenerion angustifolium (L.) Scop. – S; < Chamerion angustifolium (L.) Holub – Il, Mi, Holub (1972); < Epilobium angustifolium L. – G, GW2, Pa, RAB, W, WV; >< Epilobium angustifolium L. var. angustifolium – F, Munz (1965); > Epilobium angustifolium L. var. macrophyllum (Hausskn.) Fernald – F