The Need for Seed

When Midewin was established in 1996, less than three percent of its 20,000 acres remained in native vegetation. Re-establishing prairies and wetlands on such a vast scale requires an initial 10 to 25 pounds of native seed per acre, depending on the kind of habitat. That’s a lot of seed, especially considering that there are limited sources for a limited number of native plant species.

Today’s volunteer stewardship day was all about cleaning seed, seed that had been harvested from Midewin seed beds, natural area remnants, or other approved natural area sites. Since it had been about a year since last I ran the seed cleaning machines, Jennifer, Midewin botanist, gave me quick review of the two machines I’d be running. The first was a brush machine. Think twin rows of soft scrub brushes revolving within a hard mesh drum. It’s good a good first-step instrument for breaking down the likes of smooth white lettuce.

smooth white lettuceSmooth white lettuce (Prenathes racemosa) is not threatened or endangered in Illinois, but it is uncommon enough that it is not listed in any of my native wildflower guides. Nor does it appear in the on-line database I’ve never seen this plant in the wild, but according to a 1914 manual about weeds, it is a native prairie plant – “of very stately appearance, with a stout stalk, two to six feet or more in height” with dense clusters of pale purple florets.

Once dried, those florets first need to be separated from the stalks. Into the top of the brush machine they go, like raw meat into a meat grinder. A revolving metal blade first breaks up the stalks, then the revolving brushes dislodge and break up the florets against the side of the hard mesh drum. One output contains mostly broken stems. The other output contains a mix of chaff and seed.

The seed is brown, slender and less than half a centimeter in length. It is attached to a straw-colored pappus – think funnel-shaped dandelion fluff. One could remove each pappus by hand, rather like nipping the end off a miniature cocktail umbrella. Or more efficiently turn to another cleaning machine to tackle the job en masse. The second machine uses a combination of mechanized sifting, aspiration and gravity. The chaff/seed mix gets sprinkled on a top screen that shimmies back and forth, allowing the seed to drop down to a second, finer-grade shimmying screen. From there, remaining heavier chaff is sifted to away and lighter chaff is siphoned off by a gentle vacuum, allowing cleaned seed to drop into a bin at the very bottom of the machine.

seedIt can take a couple of runs through this machine and trying different grade screens to achieve the desired goal of a “clean” batch of seed. Even then, the seed must be viewed under a microscope to ensure that it is viable, meaning that it is capable of germinating. The last time I looked at anything under a microscope was in high school biology class. If memory serves (high school was a long time ago) I wasn’t much impressed by what whatever magnified algae or frog part I was looking at. Some 30-plus years later, I was enthralled by the beauty and complexity of a tiny seed. What looked like a nondescript splinter in a petri dish became a cocoa brown torpedo deeply scored with vertical lines along its entire length. It took a while to master the tweezer point that became a 2 x 4 under the microscope, but I eventually managed to scrape away a bit of seed husk to reveal the “meat” of the seed beneath. This compared favorably to my microscopic examination of seed from various chaff outputs. To the naked eye, this seed looked no different than any other, but under the microscope it was clear that the “meat” was gone, leaving nothing but shattered husks.

From start to finish, it took about three hours to clean two small batches of stalks, resulting in a grand total of maybe five teaspoons of viable seed. If this sounds tedious, crazy, not worth the trouble, well, truth is it’s fun. As someone who makes his living largely sitting behind a computer, it’s fun learning how to operate machinery. I’m not without experience when it comes to working with my hands (I’ve rehabbed two historic homes), but in learning the various steps involved to operate the brush cleaner, for instance, a part of me felt a little bit like Cliff Robertson in the 1968 film Charley being challenged to operate the bread making machine. (That is, after he started receiving the experimental treatments to improve his intelligence.) Install correct mesh drum. Install correct brush set. Set brushes to proper contact with mesh drum. Attach top cover. Attach end plate. Bolt it in place. Attach vacuum hose. Set level of air flow. Set level of output for door one. Put on protective eyeware. Put on dust mask. Turn on machine. Insert stalks one at a time in input. Check outputs. Make any necessary adjustments. Repeat entire process if necessary.

It’s fun to listen to the hum of well-oiled machines, an echo of the many, many machines that once hummed ‘round the clock at the former Joliet Arsenal, churning out a billion pounds of TNT and nearly a million bombs, mines, shells, detonators, fuzes and boosters.

It’s fun to be entrusted with an important step in the return of an uncommon plant species to the wilds of Midewin. Perhaps most fun of all is the cultivation of patience, for it well may be a few years before the descendants of the seed I cleaned blossom on the prairie. The next step for my smooth white lettuce seeds is to propagate them indoors, with the ensuing seedlings to be planted in Midewin’s seed beds. It may take a couple of years before enough plants are established well enough to generate a sufficient amount of seed, which, in turn, would still need to be collected, cleaned and only then used to seed wet prairie restoration areas at Midewin.

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