Conium spp.
hemlocks
Europe, North Africa, and western Asia
Overview
Conium spp. is a small genus of about six species of biennial and short-lived perennial herbs in the carrot family, Apiaceae, native to Europe, North Africa, and western Asia. The widely known species, C. maculatum, poison hemlock, is a severely toxic plant that has naturalized as a weed across North America, South America, Australia, and beyond. Plants grow 3-10 ft (0.9-3 m) tall on stout, hollow, ridged stems that are smooth and marked with purple-red blotches. The leaves are large, triangular, and finely divided into a lacy, fern-like pattern, and the foliage and crushed stems give off a musty, mouse-like smell. Small white flowers are carried in many flat-topped compound umbels in late spring and summer, followed by ribbed seeds. All parts contain the alkaloid coniine and related compounds, which are poisonous to people and livestock and can be fatal if eaten. The genus grows on moist, disturbed ground, roadsides, ditches, and field edges and spreads quickly from heavy seed set.
Native Range
Native to Europe, North Africa, and western Asia, where it grows in damp meadows, ditches, and waste ground. C. maculatum has spread worldwide and is listed as a noxious or invasive weed in many parts of North America, South America, and Australia.Suggested Uses
Not grown as an ornamental because of its toxicity and weedy spread; it appears mainly as a roadside and waste-ground weed and in botanical or teaching collections of poisonous plants. Where present near pasture or crops, it is managed as a noxious weed rather than cultivated.How to Identify
Appearance
Size & Dimensions
Height3' - 10'
Width/Spread2' - 4'
Bloom Information
Flowering occurs in late spring and summer, mainly May to July, when the branched stems carry numerous white compound umbels. Bloom lasts several weeks and is followed by abundant ribbed seeds that ripen and drop nearby. Second-year plants flower, set seed, and then die.
Detailed Descriptions
Foliage Description
glossy green, finely dividedGrowing Conditions
Sun Requirements
Requires 4-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight