Saving Fossils with Sunlight: Cleaning Seeds

The past few days I had a wonderful time helping a friend, Jesse Hoffman, transform more than a dozen large leaf bags filled with seed heads of flowering plants to five small bags of clean seeds. Jesse has been doing this process at the Big Flats, New York, Plant Materials Center near Corning, for a few years: http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_015104.pdf . This is one of 27 plant materials centers operated by the United States Department of Agriculture, Natural Resources Conservation Service that serves northeastern states. It's an incredibly valuable resource for the region.

Jesse is the Preserve Steward and Botanist at the 5,380 acre Albany Pine Bush Preserve, www.albanypinebush.org, a local and national treasure that harbors rare and endangered species including the federally endangered Karner blue butterfly, two rare natural communities and fourteen rare insects. His responsibilities include replacing invasive species with native plants that help endangered insects flourish. His staff, volunteers and seasonal workers gather seed heads from selected varieties and after drying them, place them in bags. They concentrate on wild lupine which is the only plant that Karner Blue butterflies feed on and have that cleaned at the New York State Tree Nursery: http://www.dec.ny.gov/animals/7127.html in Saratoga Springs because the very large quantity of pods is too difficult to transport to the Finger Lake region. We processed New Jersey Tea, Showy Tick Trefoil, Bush Clover, Butterfly Weed, and Horsemint.

The first step tears apart the pods or seed heads to release the individual seeds using either a hammermill or a seed brushing machine. Both force the plant matter through one of a variety of screens with different size holes. The next operation then separates the mix of materials through more screens using a combination of shaking and blowing to separate the materials that are larger than (scalpings), smaller than or lighter than single seeds. This often required repeating the process a few times to remove different sizes of extraneous material to end up with pure seed. A great tool for finishing was the Clipper Office Tester, http://www.atferrell.com/clipper/products/clipper-office-tester that is small, easy to reconfigure using a large selection of screens, and runs quietly. For the first separation process we typically used a larger, floor mounted, model, and for one type, an even larger model cleaner to remove the tiny seeds from five large bins of hammer milled material.

We had budgeted more than two days, including two overnights, but finished in less so we could get home on the second day. This was only possible because Jesse had processed each variety before and knew exactly what size reducing process and screen size was best for each, and then what machine, screen sizes and air blowing settings gave good results for the final separation and cleaning steps.