[2] It grows naturally in warm-temperate to cold China, including Manchuria, and in Korea, Japan, Far Eastern Russia (Primorsky Krai) and on Sakhalin.

[4] It is a perennial herbaceous plant of 30–70 cm high, which dies down in the autumn, and overwinters with buds just under the surface of the soil.

Within the ring of stamens is a low, yellow, ring-shaped disc, that encircles the base of the two or three (rarely one, four or five) carpels, which are hairless and consists of a green ovary topped by a carmine-colored stigma.

These develop into a dry fruit that opens with one suture (a so-called follicle), that is gradually recurved, ellipsoid in shape and 2–3 cm long.

One of those combinations with 20 chromosomes is now recognised as the subspecies willmottiae, occurring in the Qin Mountains, is characterised by a hairy underside of the leaf blade.

[4] Karl Maximovich in 1859 was the first to describe this species, based on a specimen collected in the Amur Oblast, and it had rose-purple flowers.

A variety with white petals was discovered on Honshu by Tomitaro Makino and named P. obovata var.

Otto Stapf described P. willmottiae in 1916 based on a specimen from the garden of Miss Willmott, that was raised from seed that had been collected by Ernest Henry Wilson in China.

Stern revised this group of names in 1946, and suggested to merge P. oreogeton and P. vernalis with P. obovata, and to reduce P. willmottiae to a variety, but retained P. japonica.

In the most recent revision of the genus, P. obovata is assigned to the subsection Foliatae with P. algeriensis, P. broteri, P. cambessedesii, P. clusii, P. coriacea, P. corsica, P. daurica, P. kesrouanensis, P. mairei and P.

[8] The subspecies willmottiae is named after the location for its type specimen, Miss Ellen Willmott's garden at Warley Place in Essex, Great-Britain.

[9] The typical subspecies of P. obovata grows in forests ranging from deciduous broad-leaved to coniferous forests and may be found at an altitude of 200–2800 m. In China it occurs naturally in Anhui, southeastern Gansu, northern Guizhou, Hebei, Heilongjiang, southeastern and western Henan, western Hubei, northwestern Hunan, northern Jiangxi, eastern Jilin, Liaoning, southeastern Inner Mongolia, southern Ningxia, eastern Qinghai, southern Shaanxi, Shanxi, Sichuan and northwestern Zhejiang.

It also grows in Korea, Far East Russia (Amur Oblast, Primorsky Krai, Sakhalin, Shikotan) and Japan (Hokkaido, Honshu, Shikoku and Kyushu).

[1][4][5][10] The roots of P. obovata (along with P. lactiflora) are used in traditional Chinese medicine as a painkiller, tranquilliser and anti-inflammatory drug, and as a cure against cardiovascular disease and bleeding.