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Arboretum’s seed-cleaning volunteers far from dormant during cold months

April 8, 2014 By Chris Barncard

Sorting seeds

In the basement of the UW Arboretum Visitors Center, volunteers sort and collect seeds from plants collected at the Arboretum. The seeds will be used for restoration in areas that need planting in spring, summer and fall.


The rhythms of nature time the sprouting of seeds with a litany of cues — physical and chemical changes brought on by fire and frost and even the teeth and acid of a browsing animal’s digestion.

Add to that a winter ritual at the UW Arboretum, where volunteers huddle indoors with tweezers and sieves to clean bug parts, stems and other chaff from the next generation of native plants.

“Prairies like we have here developed with Native Americans and with fire and with animals like bison and elk that kept the woody material down,” says Susan Kilmer, Arboretum staff horticulturist and research specialist. “It takes a little intervention to make these processes work as they developed.”

Kilmer and a handful of seed preparation and propagation volunteers meet on most Mondays and Thursdays through Wisconsin’s coldest months. They gather in the basement of the Arboretum Visitors Center around tables and paper bags filled with the fall’s bounty of seeds, sorting and cleaning in support of the Arboretum’s restoration and research mission.

Seed sorting

The fussy and careful work of sorting seeds is carried out by Arboretum volunteers.

It’s not that the plants wouldn’t properly determine the time and place their seeds meet germinating conditions without the volunteers’ sharp eyes and patient hands picking the bracts — the outer parts of flowers — and cottony fluff from showy goldenrod seeds.

“Obviously, nature knows how to do that,” says Christine Gauder of Madison, who joined the Arboretum’s large and vital volunteer corps in the spring of 2013. “That’s why the fluff is on here in the first place.”

But the Arboretum often has to interrupt natural processes to protect them. In 2012, that meant picking over locations like Pasque Flower Hill on the Arboretum’s Raymond Road Prairie property with a heavy forestry mower, grinding away invasive honeysuckle and buckthorn shrubs with trunks up to 4 inches in diameter.

Before the mower trundled in to do its damage to the interlopers — which were crowding and shading out the native plant species prized by the Arboretum for more than 75 years — seeds were collected from Pasque Flower Hill’s populations of goldenrod, blazing star, false boneset and smooth aster and grasses such as sideoats grama and little bluestem.

“The reason we clean these seeds and care for them to the extent we do is to ensure the quality of our seed mixes, and to keep quality research data on what we’re taking off the land and putting back when it is time to sow.”

Susan Kilmer

Arboretum staff and volunteers knocked the seeds into bags, as they do while collecting seed annually from plants around the Arboretum to help reseed and restore struggling areas and spots were the ground is bare after the removal of invasive plants like garlic mustard.

“In heavy years, we have seed from 50 to 60 different plant species to work with over the winter,” Kilmer says. “And we have years when, due to heavy rains or absent pollinators, we don’t take much seed off at all.”

After cleaning, sorting and weighing, the seed collected from Pasque Flower Hill will be mixed to represent the pre-mowing distribution of plants and then the same groups of staff and volunteers will sow it in ground cleared of troublesome buckthorn.

Seed sorting volunteers

The volunteers sift seeds from chaff through sieves and separate out insect parts and other tiny, non-seed materials using tweezers.

Some more finicky seeds require a simulated winter, rotating through refrigerators for several months and stored in an unheated building that dates back to the Civilian Conservation Corps’ work at the young Arboretum in the 1930s.

“The reason we clean these seeds and care for them to the extent we do is to ensure the quality of our seed mixes, and to keep quality research data on what we’re taking off the land and putting back when it is time to sow,” Kilmer says.

That care requires attention to tiny plant structures and insect egg sacs and pieces of unrelated stems and leaves and organic detritus that rides along with the precious seed.

“It’s not always so tedious,” says volunteer Sherrie Gates-Hendrix, of Madison, while tweezing a heap of fluffy goldenrod seeds (one at a time) from the unwanted junk. “It’s just this species. The fluffier seed is the fussiest.”

“We try not to sneeze or laugh when we’re working with goldenrod,” adds Tom Henzler, another Madison volunteer. “So no jokes.”

That doesn’t mean seed cleaning is without its social side. And a jeweler’s care is not as necessary as — as Madison volunteer Allison Eyring-Green puts it — “the right personality.”

Conversation ebbs and flows the way it might over a jigsaw puzzle. Eyring-Green’s three-year-old daughter, Aileen, eyes up seeds between long breaks spent examining the pictures in plant field guides and her own (even more colorful) books.

“I saw her doing some very minute tasks at home,” says Allison, an Arboretum volunteer since 2005, “and thought, OK, this is for her.”

Bottles of sorted seeds

Bottles of sorted seeds await planting.

Seeds pass from the preparation and propagation volunteers to some partner groups like Swamplovers of Cross Plains, but most are spread during the growing season or planted in the Arboretum’s nursery, from which more mature plants are moved out into marshes and prairies.

Seed cleaning is its own kind of fun — “It’s just as much for the educational aspect,” says Kilmer, “talking about the biology and unique differences of species” — but many of the volunteers look forward to the sowing and transplanting of spring and summer.

“The fun thing was collecting and planting in Green Prairie,” Gates-Hendrix says. “You spend time getting to know parts of the Arboretum you may not see as often, and you know that this work you’ve put in all year is helping to maintain the health and beauty it deserves.”