Bupleurum (hare's-ears) is a large genus of approximately 190 accepted species in the family Apiaceae (the carrot and parsley family), placed within the subfamily Apioideae and tribe Bupleureae. It was described by Carl Linnaeus in his 1753 Species Plantarum and remains one of the more taxonomically complex genera in its family, with GBIF recording 393 descendant taxa across all ranks.
Members of the genus are annual or perennial herbs or woody shrubs, ranging from a few centimetres to around 3 metres tall. The most distinctive character of Bupleurum within Apiaceae is its simple, undivided leaves — most relatives bear compound or deeply divided foliage. The bracts subtending the compound umbels are also simple, or occasionally absent, a combination that makes the genus readily recognisable in the field. Flowers are small and yellow, borne in compound umbels with bracteoles that may serve to attract pollinators.
The genus is almost exclusively an Old World taxon, centred on the Northern Hemisphere and especially diverse across Europe, the Mediterranean basin, and temperate to subtropical Asia. A single species, Bupleurum americanum, extends into North America, and one species is native to southern Africa. The genus is well represented in Europe: Switzerland alone hosts nine species or subspecies, from lowland populations of B. gerardii to the high-alpine B. petraeum and B. stellatum.
Several species have significant economic and ethnobotanical importance. Bupleurum chinense (chai hu) has been used in traditional Chinese medicine for several thousand years; its dried root (Radix Bupleuri) is prescribed for liver and digestive conditions, and modern pharmacological work has identified saikosaponins — triterpenoid saponins — as key bioactive constituents with hepatoprotective activity. Bupleurum falcatum (sickle hare's-ear), native across Europe and the Caucasus, has been investigated for antidepressant effects mediated through the serotonergic and noradrenergic systems.
Etymology
The genus name Bupleurum derives from the Greek bous (ox) and pleuron (rib or side), a reference to the prominent parallel veination of the simple leaves, which was likened to an ox's ribs. The common name "hare's-ears" alludes to the shape and texture of the leaf blade in some species, particularly the rounded leaves of B. rotundifolium.
Distribution
Bupleurum is almost exclusively an Old World Northern Hemisphere genus, with its greatest diversity across Europe, the Mediterranean, the Middle East, and temperate to subtropical Asia. The single North American representative is Bupleurum americanum, found in western mountain regions. One species is native to southern Africa.
In Europe, the genus is widespread: Switzerland records nine species and subspecies ranging from Mediterranean-influenced lowland habitats to high alpine zones. Bupleurum falcatum spans from France through the Caucasus to eastern European Russia; its subspecies corsicum is endemic to Corsica, while subsp. dilatatum occurs in Slovakia, Hungary, and Romania. Bupleurum chinense is native to East Asia.
Taxonomy
Bupleurum L. was formally described by Carl Linnaeus in Species Plantarum (1753). It sits within the family Apiaceae, subfamily Apioideae, tribe Bupleureae. The genus holds GBIF usageKey 3034551 and is listed as taxonomically accepted. The synonym Buprestis Spreng. appears in older literature but is not currently accepted.
Plants of the World Online recognised approximately 190 accepted species as of December 2022; GBIF records 393 total descendant taxa including infraspecific ranks and synonyms. The genus is morphologically distinct within Apiaceae for its simple, undivided leaves and simple or absent bracts on the umbels — characters that place it as an outlier in a family otherwise dominated by compound leaves.
The East Asian name Bupleurum falcatum has historically been misapplied to Bupleurum stenophyllum, illustrating the nomenclatural complexity common across the genus's Asian range.
Ecology
Bupleurum species occupy a broad range of habitats reflecting the genus's wide geographic distribution. European and Central Asian species frequently grow in dry, open grasslands, rocky slopes, scrub, and forest margins. Alpine representatives such as B. petraeum, B. ranunculoides, and B. stellatum (all recorded in Switzerland) extend into subalpine and alpine zones. Mediterranean species, including the shrubby B. fruticosum, tolerate drought and poor soils.
The genus's simple leaves are thought to be an adaptation to xeric or semi-open conditions. Phytochemically, the roots of several species are rich in polyacetylenes and triterpenoid saponins (saikosaponins), which may have roles in herbivore deterrence.
Cultural & Medicinal Uses
Bupleurum has deep roots in East Asian traditional medicine. Bupleurum chinense provides the herbal drug Radix Bupleuri (chai hu), one of the most widely prescribed roots in traditional Chinese medicine. It has been used for thousands of years primarily for liver and digestive complaints. Contemporary research has documented potential benefit in treating non-alcoholic fatty liver disease through formulations containing the species. The key bioactive constituents are saikosaponins — triterpenoid saponins, notably saikosaponin-d — which show hepatoprotective activity in experimental models.
Bupleurum falcatum has been studied for antidepressant effects, with pharmacological evidence pointing to modulation of serotonergic and noradrenergic pathways, though the precise mechanism has not yet been characterised.
