At the tail end of August, I spotted three or four valerian plants blooming along Route 9. Valerian is a pretty common escapee from captivity hereabouts, white-off-white umbels in a distinctive shape, once your eye gets used to it. This sighting was kind of weird, though. Valerian by and large blooms in June and July. It was the first valerian I’ve ever seen in August. But nature’s rules, even seasonally, are often more like tendencies in categories than laws.

Water hemlock in a field in Burnham. Photo courtesy of Dana Wilde

There are other white flowers that look a lot like valerian, to an unpracticed eye. One of them blooms at the top of my driveway in Troy starting in July. Many midsummers I’ve taken samples of it among the grass, day lilies and bedstraws, and headed back to the house to try to identify it in the wildflower books.

It kind of looks like valerian, but more like Queen Anne’s lace, whose the tiny white, five-petaled blossoms grow in an umbel shaped like a flat moon. Queen Anne’s lace is also called wild carrot because the root, like a small carrot, can be dug up and eaten. So can valerian root, for medicinal purposes.

But the valerian and Queen Anne’s lace umbels are usually denser than the umbel of the flower by my driveway, and Queen Anne’s lace often has a tiny purple floret that this other flower doesn’t. You’d think these would be helpful clues to identifying it. But in fact, there are several other flowers that look so much like these two that from a distance it’s hard to tell them apart. And a mistake, it turns out, can kill you.

Water hemlock, for example, looks to the unpracticed eye just like Queen Anne’s lace. One big difference though: It can be fatal to ingest or, in extreme cases, even touch its sap. How do you tell them apart? Water hemlock has a smooth, purple-streaked stem. Queen Anne’s lace has a bristly stem. Water hemlock’s umbels tend — tend, mind you — to be more domed than the flattened moons of Queen Anne’s lace. Tiny leaflets called bracts hang under the flowers of Queen Anne’s lace, but not under water hemlock flowers. Water hemlock’s blossom time overlaps with Queen Anne’s lace, starting a month or so earlier usually. Like valerian. The critical, but invisible, difference is that water hemlock contains a powerful neurotoxin called cicutoxin.

Another plant whose umbel resembles Queen Anne’s lace, valerian and water hemlock is ginseng. In October 1992, two brothers, 23 and 39 years old, were searching for it in the woods of midcoast Maine. The men came upon what they apparently thought was ginseng, and both chewed some of its root, the younger biting off more than the older. It wasn’t ginseng.

“Within 30 minutes,” a Centers for Disease Control report stated, “the younger man vomited and began to have convulsions; they walked out of the woods, and approximately 30 minutes after the younger man became ill, they were able to telephone for emergency rescue services.

“Within 15 minutes of the call, emergency medical personnel arrived and found the younger man unresponsive and cyanotic with mild tachycardia, dilated pupils, and profuse salivation. Severe tonic-clonic seizures occurred and were followed by periods of apnea,” the report continued. “He was intubated and transported to a local emergency department. Physicians performed gastric lavage and administered activated charcoal. His cardiac rhythm changed to ventricular fibrillation, and four resuscitative attempts were unsuccessful. He died approximately 3 hours after ingesting the root.”

Within a couple of hours, the older brother was having seizures and delirium, according to the report, but he lived.

The root they ate belonged to water hemlock (Cicuta maculata, aka spotted cowbane), which the CDC says killed five people in the U.S. from 1979-88. The root contains the highest concentration of cicutoxin, but ingesting any part of the plant is potentially fatal, including the sap which can be absorbed through your skin.

It turns out ginseng looks less like water hemlock than do water parsnip, cow parsnip (aka hogweed), hemlock parsley and caraway, all of which grow in the Northeast, have edible parts, and look very much alike — which is to say not only like water hemlock, but also like bulb-bearing water hemlock and poison hemlock, both of which are also fatal to ingest. Another flower with a general resemblance to water hemlock is common yarrow, or milfoil, whose feathery-looking little leaves are however quick studies.

One June afternoon I was attracted into a field by some lovely white umbels that I thought were valerian, but turned out to be water hemlock. The flower at the top of my driveway has that umbel of small white flowers, a grooved stem and is not mottled purple. I’m pretty sure it’s not water hemlock. It has characteristics of hemlock parsley, caraway and Queen Anne’s lace, not to mention valerian (which shouldn’t even blossom in late summer), but not all of any of them.

I wonder what it is, exactly. I’m not going to eat its root.

Dana Wilde lives in Troy. You can contact him at naturalist1@dwildepress.net. His recent book is “Summer to Fall: Notes and Numina from the Maine Woods,” available from North Country Press. Backyard Naturalist appears the second and fourth Thursdays each month.