Conium maculatum L. - Poison Hemlock

Conium maculatum plant

Family - Apiaceae

Stems - To 3m tall, herbaceous, green with purple or black spots, sometimes entirely purple, often glaucous, glabrous, erect, from large taproot.

Conium maculatum stemStem.

Leaves - Alternate, large, to 40cm long, about as broad as long, ternate, glabrous, broadly ovate in outline. Leaflets pinnatifid. Lobes serrate.

Conium maculatum leaf

Inflorescence - Multiple compound umbels terminating the stems. Umbels and umbellets subtended by attenuate bracts to 5mm long. Rays glabrous. Flowers +/-15 per umbellet.

Conium maculatum inflorescence

Flowers - Petals 5, white, subequal but typically with one petal larger than the others, glabrous, to 1.2mm long, 1mm broad, cuneate at base. Apex of petal apiculate with the apiculus curving adaxially. Margins of petal folding slightly downward. Stamens 5, alternating with petals. Filaments to 1mm long, white, glabrous. Anthers pale yellow to whitish, .15mm broad. Stylopodium present, slightly flattened, greenish.

Conium maculatum flowersFlowers close-up.

Flowering - May - August.

Habitat - Waste groung, disturbed sites, pastures, open fields, low ground, railroads, roadsides.

Origin - Native to Europe.

Other info. - Although this plant may smell like fennel (Foeniculum sp.) , or Finocchio in Italian, when bruised or crushed, it should not be eaten as it is very toxic.
No other species in the family has such large and divided leaves as C. maculatum, so the plant can be easily distinguished from a distance. It is a very common weed in Missouri.

Photographs taken at the Kansas City Zoo, 5-22-00, and in Eminence, MO., 6-6-03.