Most Apiaceae are annual, biennial or perennial herbs (frequently with the leaves aggregated toward the base), though a minority are woody shrubs or small trees such as "Bupleurum fruticosum". Their leaves are of variable size and alternately arranged, or with the upper leaves becoming nearly opposite. The leaves may be petiolate or sessile. There are no stipules but the petioles are frequently sheathing and the leaves may be perfoliate. The leaf blade is usually dissected, ternate, or pinnatifid, but simple and entire in some genera, e.g. "Bupleurum". Commonly, their leaves emit a marked smell when crushed, aromatic to foetid, but absent in some species.