Poison Hemlock Identification — Is This Poison Hemlock?
Upload a photo and our free AI tells you in seconds whether it's poison hemlock or a harmless look-alike like Queen Anne's lace. Every part of this plant is lethal if eaten — learn the purple-stem tell before you touch it.
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☠️ POISON HEMLOCK CAN BE FATAL — DO NOT TOUCH, CUT, OR BURN
All parts of poison hemlock (Conium maculatum) are lethally toxic. Ingesting a small amount can kill an adult. The sap can be absorbed through skin and eyes, and burning the plant or cutting it with a weed trimmer releases toxic particles you can inhale. If ingestion is suspected, call Poison Control at 1-800-222-1222 or 911 immediately — this is a medical emergency. Identify from a photo at a safe distance; never handle it without full protective equipment.
How to Identify Poison Hemlock
Check these features before you rely on any single one — the combination is what confirms the ID.
The definitive tell. Poison hemlock's smooth, hairless green stem is streaked and splotched with distinctive purple or reddish-purple blotches. No safe look-alike has these purple markings on a hairless stem.
Stems and leaf stalks are smooth and waxy with no hairs at all. Queen Anne's lace, its most common look-alike, has visibly fine hairs on its stem — the classic memory aid is "the Queen has hairy legs."
Leaves are finely divided and lacy — three to four times pinnately compound, resembling parsley or carrot tops but larger and glossier, with a triangular overall outline.
Crushed leaves give off a rank, musty smell often compared to mouse urine or parsnips. Never deliberately crush or sniff a suspected plant — this is a feature to note only if you've already brushed it accidentally.
Small white flowers in loose, dome-shaped umbels (umbrella-like clusters). Unlike Queen Anne's lace, the clusters are more open and never have a single dark purple floret at the center.
Grows aggressively to 6–10 feet tall in its second year, far larger than Queen Anne's lace. It has a white taproot easily mistaken for a wild parsnip or carrot — a mistake that has proven fatal.
Look-Alikes: How to Tell Them Apart
Queen Anne's Lace (Wild Carrot)
The critical distinction. Queen Anne's lace has a HAIRY stem with no purple blotches, grows only 1–4 feet tall, and its flower cluster usually has a single dark purple floret at the very center. It smells like carrot, not musty. Remember: "the Queen has hairy legs."
Wild Parsnip
Not a hemlock, but dangerous in its own right — its sap causes severe blistering burns when skin is exposed to sunlight (phytophotodermatitis). Distinguished by YELLOW flowers rather than white, and a grooved green stem without purple blotches.
Giant Hogweed
Far larger, reaching 8–14 feet with leaves up to 5 feet across. Its stem has purple blotches AND coarse white hairs. The sap causes severe burns and permanent scarring. Report sightings to your state agriculture department.
Elderflower
Also has white umbel-shaped flower clusters, but elderflower is a woody shrub with opposite compound leaves and brown bark — not a hollow green herbaceous stem. It grows from a woody trunk, never a taproot.
Yarrow
White flat-topped flower clusters, but with feathery, very finely divided leaves growing directly along the stem and a pleasant aromatic scent. Stems are hairy, and it stays under 3 feet tall.
Water Hemlock
A different species (Cicuta) and considered North America's most toxic plant. Grows in wet ground, has coarsely toothed leaflets with veins ending in the notches, and a chambered root. Also fatal — treat any suspected hemlock as deadly.
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