The inflorescence consists of a branched, flat-topped cluster, each flower being radially symmetrical, with a superior ovary.

Flowers have the following components: sepals, four or five, which tend to persist; petals four or five, usually yellow, sometimes dotted with black specks; stamens many, on long filaments; styles, three to five, often fused at the base.

[6] When accepted as a complete family, the cladogram of Hypericaceae would appear as such: Cratoxylum Eliea Triadenum Hypericum Thornea Lianthus Harungana Psorospermum Vismia Many members of this family contain the naphthodianthrone derivatives hypericin and pseudohypericin; these are contained in glandular tissues that appear as black, orange or translucent spots or lines on petals, leaves and other parts of the plant.

These compounds are photosensitive and can cause reactions in grazing animals, such as blistering of the muzzle, as well as in people who come into contact with the plants over prolonged periods.

[5] The highest concentration of these substances occurs in common St. John's wort (Hypericum perforatum), which is used in herbalism and as a folk remedy.