Not Just Poisonous But Stubborn & Spreading

A closeup may be attractive, but this plant is trouble

Parsley, celery, carrots, anise, fennel, cilantro, and POISON hemlock – as they say, “One of these things is not like the other.” All are members of the carrot family (Apiaceae, formerly known as Umbelliferae), and all but one are – not only non-toxic –  but edible.

One significant challenge comes when poison hemlock, an arguably visually appealing plant, is misidentified. If ingested, as few as a handful of leaves – or any of the other anatomy, including the seeds and roots – can incapacitate an otherwise healthy adult in a matter of seconds. The potent toxin causes permanent paralysis of the muscles, including those used for breathing. Remarkably, this plant is truly lethal (ask Socrates), and there is no known antidote.

Another significant challenge is that beyond the extreme toxicity of this outwardly innocuous carrot-like impostor, poison hemlock joins a growing list of invasive plants as a true nuisance in the marsh community. Europe was home originally, but now the plant is increasingly common along roadways, railways, field edges, disturbed sites, wet areas, streambanks, pastures, and even ag land in much of the United States. According to the Ohio State University Extension program (2012), "The population of poison hemlock along field edges, in fence rows, around barn lots, and now even growing throughout hay fields seems to have reached new proportions," in the state, and its versatility is making it a rampant invader in Ohio (and beyond).

When I first sat down to write this post, I thought I’d have to commission Roy to procure some photos. There is no shortage of photo-documentation online, but I wanted images from our specific property. What I found in looking back at just about any landscape shot we’ve taken in the last three weeks is that poison hemlock is at least present just about everywhere there is relative high ground. It loves the dikes, particularly in areas where cool season grasses are thin and/or Phrag is or was recently prevalent.

Poison hemlock lining both sideslopes of the dike where the portable pump is now installed; these plants are a modest 3-6' tall, but prolific flowering means prolific seed production if we don't get ahead of them

We can attest that this plant readily grows in excess of 10 feet tall in moist, fertile conditions. A subtle side note from an Illinois source says it “likes calcium-rich substrates.” We fit that bill, too – our marl-rich soils certainly qualify.

By way of identification, the plant produces small white flowers that are typical of the carrot family, and has a smooth, hairless purple-spotted stem and dark, glossy-green, fern-like triangular leaves in addition to a fleshy, white taproot.

To confuse things further, poison hemlock is often mistaken for another noxious and toxic invasive plant called giant hogweed. It exhibits many crude similarities in form and is one that is also spreading rapidly across Ohio.

Although poison hemlock is more known for poisonings as a result of ingesting (particularly by an unsuspecting cow), I've found evidence that the plant’s natural oils may absorb through the skin. According to the University of Illinois Extension, simply handling the plant seldom causes a toxic reaction in humans, but “ingesting” it even through the eyes or open wounds can cause poisoning. For this reason, I’m now in the habit of wearing a mesh face shield and safety glasses when I’m encountering the plant with our bladed power trimmer.

Where's Waldo? Can you find the
swallowtail caterpillar happily
munching away on this hemlock?
(click to enlarge)

I just received the bill for our second mowing of the season, and couldn’t help but notice the note added IN BOLD to the invoice, “HEMLOCK BECOMING A PROBLEM” – Joe is being kind; that’s an understatement. We are trying to mow and trim more often so that grasses might outcompete. Mowing after the hemlock has bolted and before seed set will prevent seed production. But because this relative newcomer hasn't historically been prevalent enough to be problematic, we're still developing a more comprehensive management strategy.

While poison hemlock can be partially managed by mowing and tilling, it seems the most effective control approach involves properly timed applications of selective post-emergent herbicides. Flowering begins in early to mid-May and really seems to hit its stride in June on our property. It is a prolific seed producer, so applications of herbicides made now should reduce seed production.

Based on OSU Extension recommendations, there are several herbicide options. Crossbow, Banvel and 2,4-D are all thought to be fairly effective on small poison hemlock in the spring. Taller plants may can be controlled with glyphosate (Roundup) during the summer months, so we may start experimenting with selective spraying soon. Being a biennial, however, poison hemlock is perhaps most effectively controlled late in the fall. We'll be experimenting with a variety of tactics, and we're certainly open to suggestions! Eventually, I hope to be able to report back with some success stories.

Dike Maintenance: Kindly Replace Your Divots

Dike Repair: Our ever-dependable contractor (Buehler Excavating of Oak Harbor) was on-site this AM with excavator in toe.
A couple hours and a fair amount of compacted clay was all it should take to put us back on the right path. We should know 
a lot more by morning, provided the pumps continue to run and we don't get a significant thunderstorm (a low probability).

It was a busy day on the marsh. As is so often the case, there were several things going on all at once. Much of our activity was driven by dike maintenance and the ongoing effort to bring the water levels down on the neighboring marsh so that we can circle back on our final push to draw down on an additional 100-200 acres of own east side (before it gets too late in the "early" drawdown season). [NOTE: Because of stress on dike stability, it's not advisable to draw down one unit while leaving an adjacent unit in a high-water condition. Differences in head pressure tend to wreak havoc.]

After several consecutive days of dedicated searching, Roy and Nate were finally able to turn up the primary source of our neighbor's problem (and by association, ours): a significant hole . . . well, three holes, actually. Pumpzilla has been churning out 5,000-gal/min for several days in a row on the neighbor's 65-acre unit to supplement his ~1,500-gal/min pump, and we still weren't making any measurable headway. The math suggests we should be dropping 4-6" of water per day. We obviously knew there was a problem, but despite the tireless (tiring) search, they just couldn't seem to pinpoint the problem until late yesterday. Fortunately, all the hard work paid off, and Buehler Excavating came to our rescue -- as they so often do!

Meanwhile, I was showing a local fence company around an area on the north side of the property that we're considering doing some work on. I then met with the County road mowing crew and tag-teamed to get the shoulders around our entrances cleaned up. They did a great job and things look as good as they have since we moved in.

I probably moved a couple/few cubic yards of clay. I'll feel it tomorrow, but it will make for a much smoother ride atop the dike, and it will also help reduce the likelihood of a small nuisance from becoming a big problem.

Finally, I focused my attention on a remote interior dike on the West Marsh to do some much more modest hand repairs of my own. I felt like I was channeling my inner Bill Murray as I identified small (softball- to basketball-sized) holes, sinks, and slumps caused by some of the same culprits that forced the excavator repair. As critical as muskrats are to the broader marsh ecosystem, they can also be a burrowing nuisance to put it modestly. Groundhogs and beaver can also be devastating. Fortunately, the biggest of these excavating rodents, the beaver, are not very common in the immediate area.

Julie caught this snapper up on the dike recently.
She was likely seeking high ground to lay eggs.

Another source of some of the smaller "potholes" that I encountered today likely came from still other digging mammals -- namely raccoons and opossums. Roy has seen this time and time again over his years in the marsh, but he has recently been pointing out these shallow depressions all over the tops of the dikes where clay had remained exposed (devoid of vegetation).

These locales are magnets for a broad diversity of nesting turtles like the snapper shown to the left. This is especially true on warm, rainy nights in the spring and early summer, when many turtles make their way out of nearby water, dig shallow holes, and lay several to several dozen round eggs that are then recovered with a few inches of soil to incubate (much like sea turtles).

Unfortunately, opossums and even more so raccoons are very wise to this behavior, so much so that coons are known to dig on fresh clay without any other visual or olfactory cue. They are unbelievably adept at raiding nests, and when you witness the quantity of destroyed sites, just on our property, it seems a miracle any single turtle prevails. But they do. And to a certain extent, this is just a natural part of nature's "checks and balances" system.

A raided turtle nest. Note dark hole right off the point of the burdock leaf and the small, broken shells to the upper left of the hole
(they look almost like dried white rose petals).

ASIDE: Ohio is home to 10-12 species of turtle (depending on interpretation of "wild" vs. "introduced") and as many as eight of them likely call our marsh home. We hope to focus on turtle monitoring over the balance of the summer to document as many as possible. Our #1 MOST WANTED is the Blanding's turtle -- hopefully more on them soon!

Bowfin: Built to Last

Bowfin (Amia calva) displaying spring/early summer spawning colors; the vibrant turquoise of a mature male
can be difficult to fully capture on camera, especially from above

A couple months back, I briefly introduced the bowfin, a truly prehistoric fish that is actually fairly common on our marsh and throughout the backwaters of the Western Basin of Lake Erie. Thanks to a GoPro camera, I captured some underwater footage of a decent-sized female which I shared on April 12 -- to much fanfare, I might add! I promised more information, so having just stumbled onto the photo above (somehow taken a few weeks ago already), I'm making good on my promise.

Incredibly, bowfins are the only remaining survivor of an otherwise extinct group of ancient fishes that first arose more than 150 million years ago. I'm amazed in doing just a little research at how much is available online in images and in writing about a species that seems very much overlooked in the field.

But I guess it kind of makes sense. While somewhat secretive and most active at night, these relics are anything but inconspicuous. Males are smaller than females, but I'm most accustom to seeing them both in excess of 4-5 pounds -- and on the marsh and in the adjacent estuary females routinely grow to 8-10 pounds or more. Male are easily identified by a distinctive, dark "eye" spot on their caudal/tail fin (a evolutionary distraction technique also seen in moths and butterflies), and their coloration can truly look like something rendered by a Sci-Fi artist or camo designer.

Other endearing nicknames for the bowfin include, but certainly are not limited to: dogfish, mudfish, grinnel, and my favorite
-- the swamp-muskie (photo courtesy of the Ohio Department of Natural Resources, Division of Wildlife)

Additionally, "swamp-muskies" have many characteristics in common with ancient fish. Like members of the gar family, they have a "primitive" skeleton (part bone, part cartilage) and a "double skull" (an inner layer of cartilage wrapped in bone). By contrast, modern and more recently evolved fish have skeletons made entirely of bone.

Bowfins also provide parental care for their young, an unusual characteristic in modern fish. They are nest builders and voracious nest protectors (guarding eggs and then their tightly schooled offspring longer than any other fish in North America -- often for several months).

Fingerlings and juveniles, like adults, are relentless predators with a hearty appetite. Their preferred forage seems to be crayfish and other crustaceans, but they have been proven to be opportunists -- taking down, invertebrates, leeches, frogs, snakes, small rodents, birds, other fish, and even their own. That said they are not thought to be overly detrimental to the "sport fish" commonly pursued with hook and line. (Although I have heard they can be tasty to eat themselves!)

One final evolutionary adaptation of note: when the oxygen level in waters become depleted, as often happens in warmer shallow water, bowfins will rise to the surface and gulp air into their swim bladder. This organ is uniquely lined (in the bowfin's case) with blood vessels and can serve as a primitive type of lung, aiding in survival until oxygen availability improves.

P.S. Bowfins (without question, a native species) are often mistaken for northern snakeheads (another ominous invasive species). If you encounter one or the other, please make sure you understand and appreciate the difference, so that bowfins can continue to thrive in our waters.

One of my goals for myself and the kids this summer is to net and photograph some of this year's hatch. I'd love to rear young bowfins in an aquarium for a bit. There is so much more to  learn about this amazing critter. If you want more info, the best article I've found thus far comes from a post doc who works at the Shedd Aquarium in Chicago: Adventures with Bowfin, North America’s Underdog(fish) -- great photos and it is truly worth the read.