Hemlock

Conium maculatum

The man.... laid his hands on him and after a while examined his feet and legs. Then pinched his foot hard and asked if he felt it. He said "no";  then after that, his thighs; and passing upwards in this way he showed us he was going cold and rigid. And then again he touched him and said that when it reached his heart he would be gone.
Plato on the death of Socrates

Hemlock is poisonous, so poisonous, that it was used for executions in ancient Greece. The most famous victim of hemlock was Socrates who was condemned to death for corrupting the young minds of Athens in 399BC.  You should treat hemlock with respect and know how to distinguish it from other members of the Apiaceae because even casual contact with the plant can be dangerous. For example, using the hollow stems to make a blow-pipe has resulted in burnt lips and nausea.

1. Bank of hemlock by the lake

Taxonomy

Hemlock belongs to the Apiaceae or carrot family which has been discussed in general terms in a previous blog. These tend to be statuesque flowers with compound leaves and flowers arranged in umbels. They can be difficult to separate out from each other and you may have to pay attention to how the compound leaves are divided, and the presence of bracts and bracteoles. The genus name Conium is derived from ancient Greek and may be derived from the word konos meaning to whirl because vertigo may be a symptom of hemlock poisoning. The second part of the binomial name, maculatum, derives from the purple spots on the stems that are a diagnostic feature of hemlock.

Habit

Hemlock grows upright and around Leazes Park lake grows to shoulder height. The stems are smooth with purple blotches (picture 1) and as soon as you see this you know that you should treat the plant with respect. The purple spots become more obvious as the plant matures but they can still be seen on immature plants that have yet to flower. A casual inspection reveals that the plant has a more delicate lace appearance compared to cow parsley which is also now past its best in the park (mid-June).

Leaves

The basal leaves are 2-4 pinnate and have an overall triangular outline. The leaflets have a somewhat glossy appearance compared to other members of the family, particularly in immature plants. The upper leaves are similar but smaller. The leaflets have serrated edges (pictures 2 and 3).

Inflorescence and flowers

The inflorescence is more globular than the more flat-topped cow parsley. The primary rays are subtended by bracts that point downwards and the secondary rays by bracteoles that oddly are not arranged evenly around the circumference of the secondary umbels. As with other members of the Apiaceae, there are five notched petals and although broadly speaking there is radial symmetry the petals on the outside of an umbel tend to larger than the centrally facing petals. There are five stems alternating with the petals. The ovary is inferior and 2 styles can be seen protruding above the plane of the petals.



2. Purple blotches on the stem.


3. Triangular shaped basal leaf.

4. Upper stem compound leaf.


5. Inflorescence from below showing bracts and bracteoles.


Where to find Hemlock

Hemlock crops up in a few locations including but the best I find is the shaded area to the south of the lake (figure 6 arrowed in red).

6. Some good places to find hemlock (arrowed in red).


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