Arboretum "Bank" Is for Saving Seeds

April 16, 2016

By L. Clark Tate 

brett hall

A rainy day fund or a stack of cash squirrelled away protects against an unexpected event. Seed banks have the same purpose: to guard against unanticipated occurrences that beset plants, such as droughts, floods, catastrophic fires, or invasive species. Since such incidents can happen any time and potentially wipe out isolated plant species, stockpiling seeds is the invaluable goal of the Arboretum’s seed bank program, now in partnership with the ambitious California Plant Rescue Project (CaPR).

“We’ve been collecting seeds forever,” says UCSC Arboretum’s California Native Plant Program Director, Brett Hall. “We have a significant seed collection,” he notes, one filled with central California coast species. And they aren’t just squirrelled away; they are used in situ - planted in the garden – as well as ex situ - banked. The Arboretum began saving seeds in earnest around 2007. The project follows a basic economic principle: as species and their seeds become more threatened or less common, they become more valuable, and it makes more sense to invest. Luckily, the investment risk is quite low. Though some seed storage facilities resemble large locked-down containers, the Arboretum’s seed bank looks a lot like a regular freezer. “They don’t cost that much,” Hall says of seed banks. And potential returns, i.e. preventing plant extinctions, are truly important.

Harvesting, cleaning, drying, and prepping seeds for the big freeze takes work but creates an otherwise nonexistent safety net. And, the interest in making that net as big as possible is growing. Seed banking efforts are increasingly collaborative on regional, national, and international scales. Enter CaPR, a seed-banking consortium with the modest goal of banking the entire flora of California.

 It’s not surprising this ambitious project sprung from a botanical man-myth-legend, Dr. Peter Raven, a longtime UCSC Arboretum supporter and holder of the U.S. National Medal of Science. In January 2014, Raven got the CaPR seed-ball rolling as a loosely organized partnership of ten preeminent California botanical organizations chaired by Claremont’s Rancho Santa Ana Botanic Garden (RSABG). Members include The Center for Plant Conservation, CA Native Plant Society, San Diego Zoo, East Bay Regional Park, UC Davis Arboretum, and Santa Barbara, Berkeley, San Diego Botanic Gardens, and, of course, the UCSC Arboretum.

seed collectingPriority one for CaRP is collecting rare and endangered plants. Last year, the Arboretum took on the rare, local Arctostaphylos: Manzanita. “We think of them as among our local stars,” says Hall about the charismatic flora, a.k.a. the little apple. Manzanita—with its affinity for harsh environments and low nutrient soils; its alternatively smooth or peeling red bark, and sometimes fuzzy shoots; and its pretty flowers and tidily clustered light-green leaves—is a plant so uniquely adapted to our coastal range that it could be assigned only to Santa Cruz.

Two of the four species assigned to the Arboretum are in point of fact endemic to Santa Cruz County. Arctostaphylos glutinosa and Arctostaphylos ohloneana, composed of less than 100 individuals and named to honor the Ohlone Indians, grow nowhere else on earth. The two others are San Bruno’s Arctostaphylos montaraensis and the North Coast Range’s Arctostaphylos stanfordiana raichei, from near Cow Mountain in Mendocino County. They also live folded into California coastal range ridges, extraordinary gardens hanging between ocean and sky.

The journey from these edenesque natural arenas to the Arboretum’s gardens is a labor intensive one. “The first step is actually locating the plant, which becomes more of a treasure hunt,” explains UCSC senior Plant Science major and Arboretum student intern Alexander Matzat. Third year UCSC student and long-time Arboretum worker Reed Kenny especially likes the search: “I really enjoy seed collecting because it is mostly hiking around and identifying plants, two of my favorite things!” Once the correct Manzanita is identified, Hall and his students harvest the drupes, baby-apple-like fruits that surround the seeds, from each plant then group and place them in a paper envelope to dry:

seed cleaningNext comes the cleaning, which can be tedious, monotonous, laborious. These descriptors are used by Matzat, Kenny, and Hall to describe the sieving, screening, and peeling process for each Manzanita seed. “Seed cleaning is not my favorite job,” admits Kenny. Matzat accepts the boredom as a means to an end: “Knowing that these seeds could possibly preserve the future existence of these plants made every second spent worthwhile.”

seed cleaningWhen cleaning is completed, a small number of seeds are counted and weighed. The entire batch is then weighed to approximate the number of seeds collected. So far, the Arboretum has collected just under 25,000 Manzanita seeds for the CaRP.

With Manzanita, and the other seeds collected at the Arboretum, there’s yet another step in-between, one that Hall deems particularly important. “In my opinion, there needs to be kind of a middle ground as well where you’re actually using it [the seed],” he says. “Just having them in the seed bank isn’t enough." There must be people that know how to grow them.  So, after the seeds are prepared for banking and kept frozen for a while, some are pulled out to see if they can survive, which means tested for both viability (do they have the potential to sprout) and germination (do they actually develop). To date, those tests have gone very well. “Almost everything we plant germinates,” reports Hall. “So far so good.”

Such practices may be particularly important for Manzanita plants because they are difficult to germinate from seed and are usually propagated via cuttings. If these seeds are to be useful down the line, knowledge about their cultivation must survive along with the plants. Since one of the best ways of keeping such information alive is to involve youth, UCSC students like Matzat and Kenny are key people to a program like CaRP. Kenny, noting climate change and other factors pose a threat to California’s plant populations, is aware not all of the wild seeds can be saved so views seed banking as  "the only way to preserve some form of California's biodiversity.” Drawing connections to anthropogenic causes, Matzat adds, “Habitat loss through human expansion is the primary reason many plants are endangered so I view it as our obligation to preserve seeds to ensure the future existence of these plants.”

Such encouragement from today’s youth infuses the program with energy and optimism. “To me, the seed bank is really indicative of how forward thinking operations begin,” observes Kenny. He notes that, though currently the operation is possible only through student ("inexpensive") labor and is low on the priority totem pole, he is certain that will change: “I am confident that once the public and other scientific establishments become more aware of the urgency behind some of this work, the Arboretum seed bank and others will receive more support and be applauded for having begun while there was still time to make a difference.” 

But it's important to keep in mind a rare seed outside the context of its rare ecosystem has questionable value. Thus the question becomes if an ecosystem is destroyed, can a seed survive in a void?  According to Hall, a Manzanita in the wild needs a population-based plant community, one with birds, bees, soil microbes, and wood rats. So, though he acknowledges seed banking is only one part of the equation, he also believes not saving them is tantamount to giving up.