Growing Magazine - October, 2013

COLUMNS

Seed Research: Beyond Tradition

By Rebekah L. Fraser


Cayte McDonough examines the container of red baneberries (Actaea rubra) she has just blended to separate the seeds from the flesh.

"The research part of what we're doing is still very much in its infancy," explains Cayte McDonough as I enter her lab at Nasami Farm Native Plant Nursery. McDonough, the nursery production manager for the New England Wild Flower Society's Nasami Farm in Whately, Mass., propagates plants that are native to New England and bordering ecoregions. Her goal is to make common native species of perennial wildflowers, grasses, ferns, trees and shrubs available to home gardeners as well as commercial farmers.

Offering plants that are native to a region supports the local ecosystem by maintaining its biodiversity. Indigenous pollinators and wildlife depend on native plants for food and shelter. New England has over 400 species of native bees, many of which feed on the nectar of native plants and help pollinate crops. Butterflies are also pollinators. Some butterfly species depend on New England's native milkweeds as their larval hosts. If those native milkweeds disappear, so do the butterflies, and as a result nearby farmers lose the services of those pollinators.



Spotted geranium (Geranium maculatum) has a unique seed dispersal system that operates like a catapult.
Photos by Rebekah L. Fraser.

Collecting and preparing wild seed for germination

McDonough and her colleagues collect seeds in the wild with permission from landowners. They collect from large populations to ensure genetic diversity and limit their collections to 20 percent of the available seed to minimize the impact on the population. Recently, they've collected blueberries (Vaccinium) from Maine, New Hampshire and Massachusetts; red elderberries (Sambucus) and spotted geranium (Geranium maculatum) from the Massachusetts Pioneer Valley; and red trillium (Trillium erectum) from Wells, Maine, plus white and pink wild bleeding heart (Dicentra) and heartleaf foamflower (Tiarella cordifolia). They also propagate seeds from Garden in the Woods, the New England Wild Flower Society's headquarters and botanic garden in Framingham, Mass. McDonough has a lot to show me during my visit to the society's lab and greenhouses in western Massachusetts.

Because seed is alive but dormant, the researchers must handle it properly to keep it viable and improve the odds of germination. Each species has certain requirements that must be met before it will break dormancy. "Some requirements are well-known, and others are still a mystery to be solved," says McDonough.

A species' requirements can relate to when the seed is collected, how it is cleaned (removing fleshy pulp and chaff), the humidity and temperature at which it is stored, and when and how it is sown. Following the cycles of nature, many New England species must experience a 90-day cold period to break dormancy. Staff at Nasami Farm looks for ways to shorten the time to germination, increase germination rates, and discover the requirements for new species, those for which the germination protocol is not well-documented.

"Though the methods we use for handling seeds are often simple, the germination requirements can be complex," states McDonough, as she slides several bright red baneberries (Actaea rubra) into a clear plastic container, adds about a cup of tap water, and blends it with a hand blender. The berry contains a chemical that prevents the seed from germinating; normally a bird or other creature would eat the berry and remove that flesh.

When the water is pinkish, McDonough holds it up to the light to see whether the flesh has separated from the seeds. Indeed, the flesh has risen to the top, and the black seeds rest at the bottom of the container. She pours the flesh and pulp off, pours the seeds into a strainer, rinses them, and sets the seeds aside for drying and storage. "We collected this seed early, just as the fruits began to blush from green to deep pink. With this species, seed that is just shy of ripe often germinates in one year rather than the two years it takes more mature seed to ripen."

In preparing seed from other species for germination, McDonough often uses the blender for another purpose: seed scarification. This process, which nicks or wears down very hard seed coats, helps the seed to imbibe water, a necessary precursor to germination. McDonough has used various scarification methods for different types of seeds. Seeds from the pea family, such as sundial lupine (Lupinus perennis), respond well to a 30-second scuffing with sandpaper. Red bearberry (Arctostaphylos uva-ursi) is notoriously difficult to grow from seed due to its dense coat, but is reputed to thrive when scarred by fire. McDonough recently tried fire scarification; the seed has yet to germinate. She plans additional research on bearberry.

Pointing to a plastic zipper bag filled with brown mush, McDonough demonstrates another low-tech seed cleaning method: squishing. This sample of elderberry has been fermenting in the bag for a while. The fermentation process makes it easier to separate the pulp from the seeds. With that task complete, McDonough will begin germination trials on this native New England plant.

Read about Nasami Farm's other germination trials in next month's column.

The author is a freelance writer based in Massachusetts and a monthly contributor to Growing.