Here are some weeds we have seen in pastures the past few weeks. Some of the weeds have toxic properties, so we do need to be aware of these.
Tropical Bush Mint
This is also called bittermint (Hyptis mutabilis). Originally, we thought this was perilla mint, which does have toxic properties. We noticed a square stem with similar leaf shape. When we looked close, we could see the leaves appeared smaller than perilla, and the flower arrangement was different. It is in the same family as perilla mint – Lamiaceae. However, there are no known toxicities with this plant.
UGA Extension Livestock Scientist Dr. Jacob Segers reminds us the plants in the mint family are known to cross. This makes ID more difficult, since they all look similar. This is about as far north as tropical bush mint grows.
This is one we need to watch for. This is the time of year when showy crotalaria is blooming and everyone knows this one. It’s a summer annual in the bean family and is a tall growing weed along pastures. It’s leaves are alternate and waxy. Its flower has bright yellow petals, spirally arranged on the stalk. It forms an inflated-looking pod with kidney-shaped seeds. Showy crotalaria is toxic to all livestock. The seeds contain the highest amount of toxins. The leaves also contain enough of the alkaloids to be toxic. The leaves of showy crotalaria are toxic even when dried. Here’s some more information on Showy Crotalaria.
We are also seeing some grass weeds in pastures. Vasseygrass is starting in spots in this Bermuda pasture. This is a perennial grass with a bunch-type growth habit that does not have a significant rhizome system, like Johnsongrass. Vaseygrass is more commonly seen in wetter fields or ditches. It has a seedhead with alternating spikelets forming silky hairs around the seeds. Seeds are produced along the entire length of the seedhead branch, which is not the case with johnsongrass. One thing you will notice are hairs where the leaf and stem meet and toward the base of the plant. It also has a pretty prominent midbrib. Controlling vaseygrass is not as easy, but here is a good source for information on control of grasses in pastures: Identification and Control of Johnsongrass, Vaseygrass, and Guinea Grass in Pastures.