Hypericum iwate-littorale is a species of flowering plant in the family Hypericaceae. It is found in temperate coastal regions of the Iwate Prefecture in Honshu, Japan.[1] The conservation status of H. iwate-littorale is unknown, as it is considered data deficient by the Global Red List of Japanese Threatened Plants.[2]
Hypericum iwate-littorale is a perennial herb that grows upright to a height of tall. The leaves are directly attached to the main stem or to a very small petiolate on its sides. The leaf blade is egg-shaped and paler on the underside. It has many pale point-shaped glands that are black or reddish. Each inflorescence can have anywhere between three and around thirty flowers from three nodes. These flowers are around in diameter with five bright yellow petals. There are many stamens in fascicles of three, with black anther glands. The seeds are dark brown and cylinder-shaped.[3]
Hypericum iwate-littorale was first described by Hideo Koidzumi, a Japanese botanist, in the Journal of the Plants of Iwateken (J. Pl. Iwateken) in 1937. Arika Kimura doubted the validity of the species, however, and placed it as a synonym of Hypericum pseudopetiolatum in subsect. Erecta. In 2003, as a part of his monograph of the genus Hypericum, Norman Robson restored H. iwate-littorale to the status of species and placed it in series Hypericum because of its raised stem lines with gland dots. He noted its similarities to Hypericum tosaense, but decided its minor differences in appearance and wide separation geographically warranted its inclusion as a separate species.
The species' current placement within the genus Hypericum can be summarized as follows:[4]
Hypericum subg. Hypericum
Hypericum sect. Hypericum
Hypericum subsect. Hypericum
Hypericum ser. Hypericum
H. iwate-littorale
H. momoseanum