The sidebar of Backyard Biology now lists some interesting links to other nature and photography blogs, one of which, The Naturephile, from the UK, always features some interesting nature news. Recently, naturephile described the physiological effects of the alkaloid poison in hemlock, coniine, responsible for the death of Socrates. Less than 0.2 g of the plant is fatal to humans! Coniine is a neurotoxin and causes muscle paralysis by blocking the receptor at the neuromuscular junction (like curare does). The paralysis begins in the lower extremities and moves upward, eventually immobilizing the respiratory muscles, so you basically suffocate to death.
Although the hemlock plant is native to Europe, the Mediterranean region, and southern Africa, it has been introduced (whatever for?) in California and Nebraska. It’s quite an attractive plant, resembling a tall fern. But if you see something that looks like this — stay away. All parts of it are poisonous. It grows 5 to 8 feet tall, and has a smooth stem stippled with purple streaks. Read more about this at: http://thenaturephile.com/2012/06/15/poison-parsley/
Photo from Wikipedia (http://en.wikipedia.org/wiki/Conium)