Taxonomic Relationships in the Hypericum ericoides Aggregate (H. sect. Coridium, Hypericaceae)

A taxonomic revision of the Hypericum ericoides aggregate is presented based on morphological characters. This aggregate is endemic to the western Mediterranean basin and is currently included in H. sect. Coridium. Light microscopy and scanning electron microscopy techniques were utilized to check the diagnostic value of several characters that were neglected or overlooked in previous works. As a result, four wellcharacterized taxonomic entities are accepted: Hypericum ericoides L., H. hispanicum (Pau) M.A. Alonso, Agulló, J.L. Villar, Juan & M.B. Crespo comb. nov. [= H. robertii var. hispanicum Pau], H. maroccanum (Maire & Wilczek) Rivas Mart. [= H. ericoides subsp. maroccanum Maire & Wilczek], and H. robertii Coss. ex Batt. & Trab. For each one, the data on morphology, ecology, and distribution are reported. Nomenclatural types are also included, and an epitype for H. ericoides is designated. Hypericum robertii, a plant supposed to be restricted to Tunisia, is reported from eastern Algeria.