At a quick glance you might think all the Friends do is litter pick the park each month, but we also work to improve the biodiversity in the park.

This year some of our volunteers have spent around five days carefully tackling hemlock within the park. We have barely dented the amount in the park, but have learnt a lot that will help us and the Park Management in future years.

The Trouble with Hemlock.

Hemlock can take over large patches of land if not controlled. Indeed, it has spread from the south of Mile End Park over the Green Bridge all the way up to Wennington Green in just a couple of years. It crowds out other plants and takes over. We have noticed lines of hemlock in the park, which suggests it has been spread by the council’s mowing regimes (ie seeds being picked up).

Each plant produces an average of 39,000 seeds. Hemlock has a two-year lifecycle (growing from seed to fruition and then dying). However, the seeds can lay dormant and remain viable for 3-5 years.

Wennington Green before and after hemlock removal (probably over a million seeds were removed!)

Identification

A tall, upright plant, hemlock can be distinguished by the distinctive and unpleasant, mousy smell of its foliage and its purple-spotted stems. Its leaves are finely divided and large, and its flowers are small and white and appear in umbrella-like clusters. It has hollow green stems with red or purple spots and streaks on them (like “varicose veins” some say). When poison hemlock is young, it starts as a rosette that grows low to the ground. As it matures, it becomes a tall, flowering stalk that can reach up to 2 metres tall.

Common Look-a-likes are wild carrot and cow parsley which are part of the same botanical family.

hemlock stem
Hemlock has distinct purple spots and streaks on its stems.
Lots of information on managing hemlock in open spaces
Information sheet on hemlock via nr.tulaliptribes.com

Symptoms of hemlock poisoning in humans:

  • muscle pain
  • excessive salivation
  • trembling
  • abnormal heart rate

Is hemlock poisonous to dogs?

Yes. Hemlock can poison dogs if ingested. Symptoms include:

  • frothing at the mouth
  • vomiting
  • rolling eyes
  • excessive drooling

Further information:

The Wildlife Trusts page about Hemlock

The WebMD page on Poison Hemlock Poisoning

Norwich City Council’s user friendly page on hemlock