Lomatium dissectum is a species of flowering plant in the carrot family known by the common name fernleaf biscuitroot. It is native to much of western North America, where it grows in varied habitat. It is found in the eastern Transverse Ranges and the Sierra Nevada in California.
Lomatium dissectum is a perennial herb reaching up to 1.4 meters tall, growing from a thick taproot. The leaves are mostly attached near the base of the plant, spreading with petioles up to 30 centimeters long and large blades divided into many small, narrow segments. The inflorescence is an umbel of many small yellow or reddish flowers, each cluster on a ray up to 10 centimeters long. The fruits resemble pumpkin seeds.
A Lomatium dissectum root extract completely inhibited the cytopathic effects of rotavirus. It also showed antibiotic activity against Mycobacterium tuberculosis and Mycobacterium avium.