Description from Flora of China
Herbs perennial, rarely annual, glabrous. Rootstock usually short, woody. Stem alternate or dichotomously branched, green or glaucous, base with or without fibrous remnant sheaths. Leaves entire, petioles sheathing; blade membranous, herbaceous or coriaceous, usually with parallel venation, base usually tapering into petiole. Cauline leaves often sessile, clasping, auriculate or perfoliate. Inflorescence loose, umbels compound, terminal and lateral; bracts several, conspicuous, often similar to uppermost leaves; rays few to many; bracteoles several, conspicuous. Calyx teeth obsolete. Petals yellow, greenish-yellow, tinged purple or purple, oblong to orbicular, apex narrowly inflexed. Stylopodium conic, low-conic or discoid; styles short, often reflexed. Fruit oblong to ovoid-oblong or ellipsoid, slightly laterally compressed, mericarps subpentagonal (rarely rounded) in cross section; ribs 5, filiform, prominent or obscure; vittae 1–3(–6) in each furrow, 2–6(–8) on commissure, sometimes obscure. Seed face plane. Carpophore 2-cleft to base.
This distinctive genus is easily recognized by the simple leaves and conspicuous bracts and bracteoles. Species within Bupleurum are, however, notoriously difficult to identify on account of wide morphological variation within a species, often spread across wide geographic distributions. Many Bupleurum species are difficult to characterize, as is evident by complex classifications where all possible taxonomic ranks have been used. Several taxa are recorded only from a few collections, and it is likely that future work will reduce the number of species. The roots of several species of Bupleurum are famous for their use as the traditional Chinese medicine “chai hu” for treatment of coughs, fevers, and influenza. Almost all of the species are recorded in the literature as regional substitutes for “chai hu” or for other local medicinal purposes. However, caution should be applied as a very few species are toxic (e.g., B. longiradiatum) and can result in “toxic strike” if misused as such substitutes.
Also see post-FOC publication: Wang, Chang-Bao et al. 2011. Fruit features of some Bupleurum species (Apiaceae) and their systematical implication. Plant Science J. 29: 399-408.
About 180 species: widespread in the N temperate zone, one species (B. mundtii Chamisso & Schlechtendal) in S Africa; introduced in Australasia; 42 species (22 endemic) in China.
(Authors: She Menglan (佘孟兰 Sheh Meng-lan); Mark F. Watson)