Conium maculatum

Conium maculatum "commonly occurs in sizable stands of dense, rank growth along roadsides, field margins, ditchbanks and in low-lying waste areas. It also invades native plant communities in riparian woodlands and open flood plains of rivers and streams in southern California" (Goeden and Ricker 1982) and other regions in the state. It is common on shady or moist ground below 5000 feet, especially in cismontane California.

Life Cycle: In California, "poison hemlock reproduces only from seed, both as a biennial and winter annual, and occasionally as a short-lived perennial" (Goeden and Ricker 1982).

"Seeds germinate in autumn and plants develop rapidly throughout the winter and spring. Some produce flowering stems in the first spring and die in the summer. Others remain in the vegetative stage without producing flowering stems until the second spring, thus becoming a biennial. Plants are more likely to be biennial in very moist situations. After producing seeds, the plants die in the summer ... The spread of hemlock is by seeds which can adhere to farm machinery, vehicles, agricultural produce, mud and clothing as well as being carried by water and to a limited extent wind" (Parsons 1973).

"Hemlock is capable of rapid establishment after autumn rains, particularly on disturbed sites or where little vegetation exists at the start of the autumn growing season. Once it is firmly established under such conditions, hemlock can preclude most other vegetation and established pastures" (Parsons 1973).