Q: What is this weed growing in my yard? I brought in some fill dirt from an area in the woods and now I have a weed I cannot kill.
A: What you have is called Florida Betony, Stachys floridana, or Rattlesnake weed. The name for the genus, Stachys, is derived from the Greek word stachys, which means an ear of wheat or spike, as the flowers appear to be arranged in a similar way. The Latinized English species name floridana refers to the fact that it was first named from a Florida collection. This species was thought to be restricted (endemic) to Florida until the 1940s or 1950s. However, it is now found as far west as Texas and as far north as Virginia.
The stems of Florida betony are hairy, square and upright, and grow to between one and two feet tall. It leaves looks similar to the mint family and spreads just as quickly. The trumpet-shaped flowers are white to pink and may have purple spots. The underground tuber is the reason for the common name “rattlesnake weed”. It is segmented and white and resembles the rattle of a rattlesnake. Florida betony will grow in full sun to part shade and tolerates a wide variety of soil conditions including wet or dry. Florida betony reproduces primarily from tubers but also from seed and rhizomes. Throughout the winter months, it will grow and spread rapidly, especially in the loosened soil of landscape beds.
If you are finding Florida Betony in the lawngrass your best management is to maintain a healthy, dense lawn by fertilizing, watering and mowing at the proper height and frequency. If it is growing in flower beds, remove as much of the root as possible, but small amounts of non-selective herbicide may be required for best management. It is aggressive and will take over an area if not kept in check.