Identify this upright branching weed with long leaves and reddish stems

Question

I'm looking to identify the weed pictured below. It's been showing up and spreading around my area for the past several years. It grows in large patches around the pasture. They start out and seed at about 2' tall and if it's the same growth I'm think I see later in the year, which grows in the same areas, it gets about 6' tall and woody, though I wouldn't swear it's the same plant. It could be another that takes over from it. The leaves are across from each other. The stem is brownish-purple. It put out clusters of small white flowers that don't appear to fully open. They look like little cups. I also noticed when taking this pictures that it had what appeared to be a couple of very small string bean looking pods on it. You can see them in Pic1 and at the end of the branch, going to the left, in Pic2.

Please help me identify this plant. It's growing wild in the pasture in SC. Thanks.

Answer 1

Apocynum cannabinum, Hemp Dogbane. It is in the same family as milkweed and has a milky sap if the stems are broken. The plant is poisonous to (at least) humans, dogs and livestock if eaten. The sap is potentially an irritant to skin, causing blisters. And yes, those string bean like pods are seed pods.

Control in the pasture would likely be best accomplished by cutting it down on a regular basis. Pulling it out or plowing it under is unlikely to help much as the plant grows from rhizomes underground, any fragments left behind tend to sprout all over again.