Bristle Briar. The plant is inedible, but its view delights the duplicates. If you put it in a flower vase, it will have a positive effect on the Decor. There are no other uses for it, and it yields no crops. You can often find it in the starting area, among other plants.
Wheezewort. An unusual plant that can only be found in the cold biome. Other than its positive effect on Decor and interiors, it has a certain very interesting quality. Namely, it absorbs warm gases from around itself and reemits them a few degrees colder. You can use it as bio-air-conditioning of sorts.
Thimble Reed. It's a special, wetland plant, which will enable you to make clothes for your duplicants. It grows very fast and provides up to 5 harvests of a special resource - Fiber Reed. The plant need warm temperatures, between 25 and 45 degrees, and water. You can plant it only on special fields - Aquatic Farm Tiles, which need to be submerged. The plant itself can be found in the warm, green biome.