Greek hyper—above, icon—image; referring to the traditional practice of hanging stems over religious icons to keep evil spirits away.
Herbs, subshrubs, perennials and occasionally shrubs. Stems occasionally angled or with expanded 'wings'. Leaves evergreen or deciduous, opposite, occasionally whorled, entire, often with black or translucent dots. Flowers yellow in terminal clusters, short-stalked. Petals and sepals 5. Stamens numerous, free or in 3 or 5 bundles opposite the petals. Ovary has ovules with axile or parietal placentation; styles 3 or 5, fused or separate. Fruit a capsule splitting along the partitions or occasionally berry-like.
Less frequently grown species include H. coris L. from S Europe which has linear leaves.
Several clumping species include H. cerastoides (Spach) N. Robson [H. rhodopaeum Friv.] which also forms prostrate tufts and has slightly larger leaves but with stems and foliage densely hairy, and H. reptans Hook. f. & Dyer, low and mat-forming with leaves less than 1.5 cm long.
Several other species described here have leaves less than 2.5 cm long and have become environmental weeds, most notably H. perforatum L., St John's Wort from Europe, which flowers prolifically and has black dots on the leaf undersurfaces; this is a declared noxious weed in ACT and NSW, also in Victoria except the metropolitan area and Western Australia except for a few areas. In Tasmania it is secondary and prohibited. It was first innocently introduced in Bright, Victoria as an ornamental and medicinal plant in about 1880 and now infests vast areas of grazing country; one of its chemical constituents, hypericin, is poisonous to livestock.
Seeds, softwood cuttings, division or layers.
Winter-flowering. Leaves with pale or dark glands
About 400 species almost cosmopolitan but mostly temperate to subtropical northern hemisphere.
Robson (1970, 1977, 1981-90).
Key to species mostly with larger leaves and flowers (to be used with caution as other species may be encountered and intergrading hybrids are known to occur).
Source: (1997). Clusiaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.