Blue Curls


aka forked bluecurls,
bastard pennyroyal
Trichostema dichotomum

This mint family member will get your attention. The flower has five petals, two up and three down. But the speckled middle lower petal extends far out from the others, and the four stamens protrude and curl dramatically. The plant itself shows the usual mint family characteristics of paired leaves on a square stem.

Trichostema is from the Greek and means “hair-like stamens”, while dichotomum refers to the way the plant grows (forking in pairs, typical of the Lamiaceae).

Blue curls is a short (to 18 inches) annual plant of dry, sunny places, such as the power line clear-cut in Serpentine Barrens Conservation Park where I found dozens of specimens. They were growing in a swath of orangegrass plants, another species I only just learned about.


According to various sources, blue curls blooms from August through October. I don’t know if that’s the case in the Maryland Piedmont, but I’ll keep an eye open for them when I go back to that area.

This is one of twelve species of Trichostema native to North America; only two others can be found in this area, and both are on the Maryland DNR’s RTE (rare/threatened/endangered) list. T. dichotomum ranges from Quebec and Ontario south to Florida, Texas to the southwest, and Iowa to the northwest. It’s rare in Indiana and threatened in Michigan. In Maryland look for it in the Piedmont as well as parts of the coastal plain, the Blue Ridge, and the ridge and valley provinces.