Native to Europe, and introduced to California, where it now is extremely common as a roadside weed throughout central to southern California.
A perennial weed with extensive root systems and woody stems. Foliage dies back in the winter, and new growth sprouts quickly from the roots in the spring.
Propagation is from seeds and from roots. Foliage is cultivated for its licorice flavor, and the aromatic seeds are also used as a cooking ingredient. Fennel is the principal foodplant of the caterpillar of the Anise Swallowtail butterfly.
Mature plants grow as high as 7 feet tall, with woody, straight, erect stems, that are branched along their length. Stems are cylindrical and are distinctly striped with longitudinal lines or furrows.
Leaves are many-divided into thin, thread-like segments, giving them a fine, feathery look and feel. The foliage is present mainly on the lower half of the plant, with the upper half of the stems devoted to the wide, umbrella-like flower heads. The leaves grow on swollen, inflated stalks that clasp the stems.
Flowers are yellow and small, and in large, flat clusters composed of numerous stalks, with numerous flowers on each stalk. These give rise to the small seed pods, each with 2 seeds.
Characteristicts Important to Control:
A vigorous perennial that regrows from rootstock or from seeds. Highly drought tolerant, it grows well along dry roadsides and waste areas.