The path climbs slate steps before slanting left through oakwoods alive with the song of warblers. Green caterpillars wriggle in flycatchers’ bills (less effort to catch than flies, I suppose). Clouds of midges dance in shafts of sunlight. A long climbing traverse with views of Yr Wyddfa lures you on, takes you to the wood’s boundary. I lean against a wall, look around, and down to my right in a moist ditch see a plant of which all who venture into the Welsh countryside should be very wary. It’s an umbellifer, less tall than hogweed. I check out crucial detail. White flower-clusters are already present. Stems are hairless and hollow, lacking purple blotches low down that would identify this specimen as Conium maculatum (hemlock). It’s Oenanthe crocata – hemlock water dropwort, deadliest of all British plants, every part of it very poisonous. A member of the carrot family, it has pale, tuberous roots – dead man’s finger. Foragers beware! I first encountered it when I lived in Cwm Pennant in the mid-1970s. Three friends who rented the small cottage of Tanygraig used to call for tea at my house up-valley. They were pleasant idealists, committed to an alternative lifestyle, living as much as possible “off the land”. They gathered some of those tubers from the riverbank, grated them into a salad, served it up with sorrel and dandelion and ate it with home-baked bread. Later that evening they fell violently ill. All three were taken to hospital in Bangor. Seeing this isolated specimen at the margin of an Eryri wood reminds me of Plato’s account of the death of Socrates in 399BC. He was found guilty by an Athenian court of impiety and of corrupting youth through his teachings. He chose to die in his prison cell by drinking juice of the common hemlock, which works on the central nervous system and results in asphyxiation – a prolonged and unpleasant way to die. I pass through the gate and leave the wood, sit with my back to a solitary oak in the field beyond, put these dark thoughts aside and delight in the wood warbler’s song.