Rehmannia henryi

The Rehmannia henryi is a rare Chinese perennial with erect stems, producing from spring to autumn, large tubular flowers in old pink with a darker heart, with an exotic appearance. Robust, it requires a very well-drained soil to thrive but can tolerate periods of drought, and can grow in both full sun and partial shade.

This curious species belongs to the no less curious family of Orobanchaceae, which includes mostly semi-parasitic plants such as broomrapes or louseworts. In its natural habitat, it grows along paths, on rocks, and sometimes in the crevices of cliffs. Stiff stems emerge from a rosette of wrinkled leaves, medium green sometimes shaded with brown-red, and semi-evergreen, coarsely toothed. The whole forms a sparsely leafy clump 35 cm (14in) tall and about as wide. Over a long period, from May to September, this Rehmannia produces short clusters carrying beautiful pink tubular flowers, with a purple heart. Two large golden stamens embellish the whole. These flowers, large in proportion to the plant, resemble the flowers of the incarvillea (even though the latter belongs to the Bignoniaceae family). The petals are widely recurved, allowing pollinators to land easily on the edge of the corolla. The corolla is also scattered with stiff and woolly hairs, giving it a slightly tousled appearance.

The Rehmannia henryi will be comfortable in a not too rich soil, in partial shade or in full sun, but above all, perfectly well-drained; in heavy soil, its longevity will be much shorter, and its hardiness can be compromised. However, it can endure periods of drought.

It can be paired with plants that enjoy partially shaded rocky conditions, such as Saponaria ocymoides, Geranium renardii, Veronica liwanensis, or Campanula poscharskyana. It will bring its exotic touch alongside neighbors like Asarum caudatum, Naples cyclamens, or stinking hellebore. It is also possible to cultivate it in a pot, in a "mini-rockery," being very careful with watering and choice of substrate.

Rehmannias have long been used in Chinese pharmacopoeia under the name Shu Di Huang. They are believed to combat diabetes and fevers.