Yesterday John and George explored the natural area adjacent to Bert Winters Park on the Intracoastal in Juno Beach. This disturbed scrub habitat is in part a scuffed-up area showing signs of invasive exotic removal, and has a small pond surrounded by a sedge-lover’s paradise of wet-mud-plants. Like any recently disturbed area, the botanizing is fun, and the wildflowers were pretty and plentiful: Coreopsis, Frostweed, Hempvine covered with puffy fruit clusters, Jeweled Blue-Eyed Grass looking like a little blue garden iris, Pineland Scalypink blooming on the sunbaked sand, Procession Flower parading across the dune side, Skyblue Lupine, and striking Beautyberry in full berry.
Photo above: Procession Flower by JB
Photo above: Skyblue Lupine by JB
Such a dandy menu – so hard to select a species to feature. So how about the most beautiful of all: Pokeweed.
Phytolacca americana is a fascinating species, at least to a die-hard plant enthusiast. We’ve all heard of Poke Sallet Annie who used to make a mess of it, after careful boiling it to defuse the toxins. Poke sallet (salad) has had such prominence as an “edible” green they used to can it, a bad idea. They also used to color wine with the berry juice, another bummer. As kids we used to smear the berries on as war paint, again, not optimal. And here is why:
The plant contains kickass bioactive compounds. The roots or even the berries can kill a person in a jiffy. But the acute toxicity is not what we’re going to discuss now. More subtle and insidious are proteins called pokeweed mitogens, abbreviated PWM. For George these have the distinction of being his first Internet search, back in the 80s when you had to make an appointment with a trained librarian, and received the results on that green-striped perforated computer paper. The outcome of that primitive search was a huge literature on PWMs. You can Google pokeweed mitogens on your own now with no help from the librarian. (That’s a hint—do it.) These compounds, merely from touching the plant, repeat, from just handling the foliage, stimulate the human immune system to proliferate white blood cells. PWMs work in ultra-minute concentrations. No thanks on that sallet, Annie.
Photo above: Pokeweed by JB
Why was this not discovered until recently? The PWM effects don’t seem to cause any known symptoms. You don’t feel ill, but if you go in for a routine blood test you might raise some eyebrows. (That is how the effect was discovered.) These super-charged proteins have taken on a life of their own in immune-cell medical research. Poke the Pokeweed, it pokes you back.
There is additional interesting Pokeweed biochemistry—antiviral compounds for instance—but let’s move on to bigger things. This species is a master weed. It builds up a massive root that can pose as a parsnip, which is how it has snuffed occasional vegetable gardeners. The root could survive a nuclear attack and provide poke salad to the mutant post-apocalyptic survivors. (They will have bigger concerns than proliferating white blood cells.) Even more interesting are the seeds.
Squash one of those black berries (oh yea, right, don’t touch it). There are 10 seeds like bullets in a revolver. Now you might think, “that’s nice, the birds eat the berries and disperse the seeds like any old berry maker plant.” True, but with an odd twist. The seeds have varied “wait times” for germination. If you pluck out the 10 seeds and plant them, some will sprout right away, and others won’t. Some have a built-in delay documented to last at least 40 years. This weed is banking for the future! When a bird drops the seeds from one plant, not only is it being dispersed in space but also in time. Some of those delay-action seeds get into the soil, then a new forest grows up, a cyclone blows the forest away, and ta-dah(!) pokeweeds sprout forth after a very patient wait.
This is getting long, but there’s one more important thing, so just keep reading. Pokeweed has an odd geographic distribution pattern. The species comes in two varieties. The “normal” variety, variety americana, with droopy flower clusters is widespread across much of North America. What’s weird is variety rigida, which, by contrast, holds the inflorescence upright. Variety rigida is confined to the Atlantic and Gulf coasts, mostly in a razor-thin seaside strip as narrow as a mile or so, stretching from approximately New Jersey to Texas. The only area where it occurs inland is across all of Florida, which is not exactly inland. You might think the difference is environmental—maybe those coastal briny breezes influence the angle of the dangle, but life is never so simple. If you take seeds from perky variety rigida and cultivate them inland where its droopy cousins dwell, the rigida grows up proudly erect, indicating a genetic component to the puzzle.
Now that’s just wacky. Geographically, upright variety rigida is a thin wrapper on the edge of a huge dangly variety americana population. Along the coast the two grow in close proximity. I mean, start at the beach, spot the upright rigida on the dunes, walk inland a mile and the inflorescences droop. Birds no doubt constantly carry rigida seeds into americana territory and vice versa, yet the two persist as distinct (there are occasional intermediates). Go figure!
The take-home lessons are these:
1. Do not eat the Pokeweed even if Grandma did, even if Grandma boiled it. If you are a Grandma, do not serve it.
2. Do not handle the Pokeweed if you are having blood work anytime soon, unless you want to have some fun with the doctors.
3. If you clear the forest, time-delay Pokeweed may rise up and say hello.
4. Because we live in Florida, our Pokeweed has upright flower clusters, but who knows why.