Identifying Poison Hemlock (Conium maculatum)

To forage safely also involves being able to identify what is dangerous and deadly. Personally I would advise against foraging for any of the close lookalikes.

I have identified these as hemlock, despite AI identifying some of them as other plants of the chervil family. If I am wrong, it re-inforces why you should leave all these lookalikes alone.

The details below are edited and re-organised from a ChatGPT answers

🚫  Key Traits:

  • Smooth, hairless stems, often with purple blotches or streaks.

  • Ferny leaves (like parsley or carrot tops).

  • Strong musty/mousey smell when crushed – although it is advised not to touch any part of the plant.

  • Can grow very tall (up to 2.5m).

  • Typically found in disturbed ground, ditches, riversides.

🧪 To Positively ID:

  • Check stem texture (hairy vs smooth). Hemlock is smooth.

  • Smell the crushed leaf (hemlock = foul; sweet cicely = anise)

  • Look for blotches on the stem (blotchy + smooth = hemlock)

🌿 Lookalikes that can be confused with Hemlock

Here are some plants often mistaken for hemlock that have hairs on the stems and may show purplish colouring:

1. Cow Parsley (Anthriscus sylvestris)

  • Hairy stems

  • Can have some purple tint

  • Umbel flowerhead like hemlock

  • Grows early spring to summer

  • Edible when young, but can be confused with hemlock, so avoid unless 100% sure

2. Rough Chervil (Chaerophyllum temulum)

  • Purple-blotched and hairy stems

  • Often confused with hemlock, but is also toxic

  • Not edible

3. Hogweed (Heracleum sphondylium)

  • Hairy stems, can have purple patches or streaks

  • Broad leaves with jagged edges

  • Sap causes burns in sunlight (phytophotodermatitis)

  • Edible parts when very young, but handling must be careful

4. Sweet Cicely (Myrrhis odorata)

  • Hairy stems with aniseed smell

  • Ferny leaves, similar umbel flowers

  • Slight purple flush possible

  • Edible and delicious, but must be positively ID’d due to confusion with hemlock

⚠️Poison Hemlock flowers
Hemlock flowers can help with identification, but it’s important to be careful because many edible umbellifers have very similar-looking flowers. Here’s how poison hemlock flowers compare to others like sweet cicely, cow parsley, and the like:
  • Tiny white flowers arranged in umbrella-shaped clusters (umbels)
  • The umbels are flat-topped or slightly domed
  • Can be large, with many clusters per plant
  • No sweet smell – sometimes a musty or unpleasant odor
  • Grows on smooth, hollow stems, often with purple blotches
  • Blooms later than others – often June to August in the UKd
✅ Sweet Cicely flowers
  • Also white, in similar-looking umbels, but:
    • Smaller and more delicate
    • Often has fewer rays per umbel than hemlock
    • Appears earlier in spring (April–June)
  • Most importantly:
    • The plant smells sweet – strong aniseed scent in leaves, stem, and even flowers
    • Hairy stems and leaves, not smooth
    • No blotches on the stem
🌼 General Tips When Comparing Flowering Umbellifers:
FeatureHemlockSweet Cicely
SmellMusty/mousey (unpleasant)Sweet, aniseed-like
StemSmooth, blotchy purpleHairy, green or slightly flushed
Flower timeJune–AugustApril–June
Flower shapeLarge, flat-topped umbelsSmaller, looser umbels
Leaf textureSmoothSoft, hairy

Flowers can help, but aren’t reliable on their own. The smell, stem texture, and time of flowering are your safest clues.