Great mullein (Verbascum thapsus) is a plant that most people have probably seen, and yet many of them may not have given the plant a second thought. In part, this may be because it is so common along roadsides and waste areas, especially those that are dry and that have clay or rocky soils. Some people might be surprised to learn that it has medicinal qualities.
Though widespread in the United States, this plant is not native. It was introduced from Europe and Asia. It is common in many areas of the UK.
As mentioned, this is a plant of waste places. In fact, to be healthy, poor and rocky soil is normally needed. Nutrient rich dirt hinders good growth and can prevent the plant from growing at all. However, this also means that this is one of the few plants that can flourish in soils that are extremely weak, with very little moisture. This species, related to both figworts and foxglove, is drought tolerant and often grows in places with full sunshine and sustained heat.
In the first year, great mullein is a ground-hugging and unassuming plant. The leaves are large, with the larger leaves often being 3-4 inches long and about half that in width. The height of the first year plant is seldom more than a few inches. However, it can be identified easily because the fairly oblong leaves are covered with fine hairs. This gives them a soft, furry feel. In other words, they are soft to the touch. The leaves are gray-green in color.
In the second year, the plant produces the flower spike. As it is doing this, the still fuzzy leaves also grow much larger. The flower spike has few leaves, though. Most of them are still around the rosette of leaves at the base. However, even the rosette is farther off the ground than with the first year plant.
The flower spike is a thick stalk arising from the center of the leaf rosette. Fully grown, it commonly reaches six to eight feet in height and sometimes taller. There is a single stalk per plant, however it can have branches off the main stalk, making it look rather like a smaller version of a saguaro cactus in form. The stalk is also quite fibrous and hard to break.
The flowers are connected to the stalk and those closest to the base open first, though once they start opening, they can open anywhere on the flowering head. The color is a sulfur yellow. The tube-shaped flowers aren't especially attractive, though they do add a splash of color here and there, to the landscape. The flowers are mainly pollinated by bumblebees.
Roots and seeds
The roots of the plant tend to be shallow but expansive to hold the weight of the flowering spike. Because of this structure, and the preferred rocky soil, there is little danger of being dislodged or blown over in even a stiff wind.
The seeds are even more remarkable. This is because they have the ability to lay dormant for years or even decades before germinating.
Great mullein was imported to the US primarily for its medicinal and other properties. It is now common. This is still a plant that many people can't name, though they may have seen it countless times when travelling.