One of our most famous, or perhaps that should be infamous, plants is hemlock (Conium maculatum) which is well known to be deadly poisonous, it is the plant that killed Socrates! Whilst everyone has probably heard of it how many people would actually recognise it if they saw it in the countryside?
Hemlock is a member of the carrot family and has the white umbel flower that carrot family members often have. It can look much like hogweed or cow parsley or any one of a number of plants but it does have one distinguishing feature, it has dark blotches on the stem which is unique. It also has a very unpleasant smell if the stem is squashed or bruised but if you decide to put this to the test make sure you wash your hands well afterwards. Flowering from June through until August it can be found on roadsides and waste ground, usually on chalk soils.
The plant contains a number of dangerous chemicals which are the cause of its toxicity and even small does are sufficient to kill both humans and livestock. So, for those who like to collect and eat herbs from the hedgerow or indulge in herbal remedies, make sure you know hemlock when you see it.