|Queen Anne's Lace- Wikimedia|
|Early leaves in April|
May is the time that the flat mats of Poison Hemlock bolt, rapidly shooting up to their mature height of 5-8 feet. This growth before other plants have their wits about them ensures that sunlight won't reach the neighbors. They hang on through the summer, their stems developing purple blotches.
Poison Hemlock (Conium maculatum) is a native of Europe, Central Asia and North Africa. It is a member of the carrot family, with foliage reminiscent of also non-native Wild Carrot (a.k.a. Queen Anne's Lace). There the resemblance ends as Hemlock has ridged stems with purple spots and smooth leaves. There are good pictures at missouriplants.com.
Poison Hemlock was the drug of choice for execution in Greece, made famous by the description of Socrates' death. It contains coniine, a toxic alkaloid similar to curare, which blocks neuromuscular transmission, leading to progressive muscular paralysis over minutes to hours and eventually death by suffocation. If only Socrates had CPR by a kind soul and a ventilator, history would have been changed.
|Poison Hemlock Root|
For those of us without livestock, this invasive plant can take over a pasture or disturbed soil in several years, shading out all the native vegetation before they get a start. Missouri University has good information on controlling poison hemlock.