Veronicastrum villosulum

Veronicastrum villosulum is a rather unusual representative of this genus of perennial plants, better known for the imposing Veronicastrum virginicum. It is a creeping plant with long stems that are initially upright and then trailing and capable of rooting upon contact with the soil, much like a periwinkle. Its small deep bluish-purple flowers bloom in late summer, accompanied by densely hairy foliage that takes on beautiful bronze to red-purple tones in autumn. This semi-evergreen, hardy and undemanding plant is an effective, original and elegant ground cover for the base of shrubs or woodland settings. Its naturally trailing habit will also be highlighted if planted above a wall.

Veronicastrum villosulum is native to Japan, specifically the island of Honshu. It is resistant to cold winters (-20°C). In the wild, it can be found in forests and groves or sometimes hanging on rocks, at an altitude between 300 and 500 m (984 and 1640ft). This perennial develops green stems covered with short hairs, which trail before reaching a height of 50 cm (20in), and root upon contact with the ground. Its rapid growth allows it to cover the ground quite densely within about 2 years, discouraging the appearance of weeds. The foliage is semi-evergreen, disappearing completely in a severe winter. The leaves of this Veronicastrum are 4 to 7 cm (2 to 3in) long and 2 to 5 cm (1 to 2in) in width, ovate to lanceolate and hairy with toothed edges. The unassuming flowering is late, generally from late August to early October, in the axils of the leaves. It takes the form of small glomerules or pompoms, 1 to 4 cm (0 to 2in) in size, composed of tiny, deep violet flowers, adorned with prominent yellow stamens. After flowering, the foliage takes on beautiful colours ranging from yellow to pink and purple-violet if the plant receives some sunlight. In winter, the leaves that have remained attached to the stems are light green with a beautiful purple reverse.

Veronicastrum villosulum is a good ground cover, useful for the base of deciduous trees and shrubs, provided that the soil is not too dry. It is a good plant for partial shade or light shade and will appreciate some evening or morning sun, and humus-rich soil. Place it in an exotic-looking group under Fatsia, Aralia or at the base of bamboo. It will also thrive in a slightly moist and shaded rockery, or planted on top of a wall, alongside adventives or the yellow strawberry Waldsteinia ternata, which are also hardy.