Abstract: Cytological, morphological, and geographical studies of Epilobium angustifolium in China reveal two partly distinct, partly overlapping entities that are best treated as subspe- cies.  The diploid (n=18) subsp. angustifolium has smaller, triporate pollen grains, typically glabrous stems and leaves, and smaller leaves and flowers, and occurs in colder, more northern areas, and at higher elevations in overlap zones.  The tetraploid (n=36) subsp. circumva- gum has larger pollen with a mixture of quadriporate  pollen  grains,  pubescent  stems  and leaves, and larger leaves and flowers, and occurs in warmer parts of southern China and at lower elevations.  We report 11 chromosome counts, six diploid and five tetraploid, includingthe first reported tetraploids in Asia.