A low, nearly evergreen shrub, with a creeping root-stock and erect, obscurely angled, unbranched stems, 12 to 18 in. high. Leaves rich bright green, ovate oblong, 2 to 3 in. long, slightly odorous, with little or no stalk. Flowers solitary, rarely in pairs, at the top of the stem, 3 to 4 in. across, bright yellow; petals obovate; sepals green, roundish, 3⁄4 in. long; stamens in five bundles, yellow, 3⁄4 to 1 in. long, very numerous; styles five. Bot. Mag., t. 146.
Native of S.E. Bulgaria, European Turkey, and N. Anatolia. Introduced by Sir George Wheeler in 1676, this has proved so well adapted to our climate as to have become naturalised in some parts of the country. On the whole, it is the most useful and not far from the most beautiful of hypericums, admirable for making a dense carpet on the ground in half-shaded places beneath trees, etc., where most shrubs would not thrive, flowering from the end of June to September. In hard winters it loses much of its foliage, and in any case, if a clean level growth is desired, it is best to cut the old stems down to the ground just as the new growths are pushing from the base in spring. Propagated with the greatest ease by dividing up the plants.
H. oblongifolium Choisy H. cernuum D. Don – This species, a native of the Himalaya from W. Pakistan to Nepal, is perhaps not in cultivation at the present time. It is placed by Dr Robson in the same group as H. calycinum. For a description see Flora Iranica (1968), Guttiferae, p. 4.
The H. oblongifolium of Wallich and the H. patulum var. oblongifolium of Koehne are not this species but H. hookeranum. The H. oblongifolium of Bot. Mag., t. 4949, is H. lobbii.