Which of these plants is commonly referenced as an herbaceous ornamental?

The plant referenced as an herbaceous ornamental is Pachysandra. Herbaceous ornamentals are typically non-woody plants that die back to the ground in the winter but regrow each spring. Pachysandra, in particular, is a ground cover that thrives in shady areas and is known for its lush green foliage and ability to create a dense carpet-like appearance. Its aesthetic appeal, along with its low maintenance requirements, make it a popular choice in landscaping.

On the other hand, Juniper is a type of evergreen shrub or tree characterized by its woody growth and persistent foliage. Email does not pertain to any plant and seems to be an unrelated option. Forsythia is also an ornamental shrub but is woody, not herbaceous, as it retains a woody structure and blooms in early spring with bright yellow flowers. Therefore, Pachysandra stands out as the correct example of an herbaceous ornamental plant.