1a. var. argentea

Stems relatively slender, inconspicuously ridged. Inflorescences spikes, these sometimes grouped into small panicles, the flowers attached to a more or less tubular, stemlike axis. 2n=36, 72 (mostly 2n=72). July–October.

Introduced, known thus far only from St. Louis County (native distribution not known, widely but escaping sporadically in the U.S.). Banks of streams; also open, disturbed areas.

Plants of var. argentea tend to be taller and with more slender stems than those of var. cristata. Sometimes, partial fusion or expansion of the inflorescences can be observed, and although such plants are probably best referred to var. argentea, their inflorescence structure is somewhat intermediate between the two varieties.