Explore a world of citrus at the Sonoma Botanical Garden in Glen Ellen

Summer has its berries and autumn boasts of apples. But citrus belongs to the wintertime. When the landscape is dreary, balls of orange, yellow and green emerge on tree branches, adding dollops of color to the garden and zest to our plates.

There is a bigger spectrum of citrus than a walk through the supermarket aisles with its navel oranges, Cuties and Meyer lemons would suggest. There are many different types of citrus and intriguing varieties and cultivars for the home gardener to experiment with.

The Sonoma Botanical Garden pays homage to the juicy world of citrus and its long voyage around the globe from its origins in Asia in a new exhibit, “From East to Zest.” A greenhouse just off a new gift shop has been converted into a warm and sunny exhibit hall filled with colorful oranges, lemons, limes, kumquats and more, many in full fruit. On display through March 5, it makes for a nice outing on cool or even rainy winter days. And when the sun is shining, visitors can step outside and onto a new, gently sloping trail that leads to the 25-acre Asian garden.

The name is a twist on the garden’s self-described theme as a “woodland experience where East meets West” and plays off the idea of the great migration of plant life that has come to the Glen Ellen garden (formerly called Quarryhill) from Asia since its founding in 1987 by the late Jane Davenport Jansen.

Citrus too, made its way west, said the garden’s Executive Director Scot Medbury, and found a toehold in Sonoma County agriculture as far back as 1855, when oranges and lemons were commonly grown along with prunes, olives and apples.

Historically, the big center of the citrus groves was the north county, with Cloverdale named the Orange District of Sonoma County in 1888. But lemons, oranges, citrons and pomelos also were growing in the Sonoma Valley in the early 1900s.

A series of severe frosts in the 1920s put an end to the citrus industry in the region, with dwindling acreage devoted to the crop. By the early 1980s, it had completely vanished as a commercial crop.

But the growing popularity of Meyer lemons has sparked a revival, boosted by the recent planting of 12,000 trees in an old apple orchard at Sebastopol’s DMS Ranch. Fun fact found in the exhibit: Recent DNA testing has shown that the original parentage of the Meyer lemon is really a cross between a citron and some kind of orange.

With the right care and conditions and microclimate, they can be nice and, in most cases, edible additions to a Sonoma County garden. “From East to Zest” features 50 varieties, all well-labeled, to explore. Please, no pilfering, however tempting. And while some, like the Buddha’s hand, a long-fingered member of the citron family, may appear exotic, all of the specimens featured in the exhibit were purchased locally, Medbury said. He did this even with the limitations imposed by current quarantines because of the Asian citrus psyllid, a pest that acts as a carrier or vector, spreading a devastating disease to citrus trees.

Most citrus are subtropical and prefer a milder climate. One reason the Meyer lemon does well here is that it is hardier and more frost-resistant than other citrus but still doesn’t easily tolerate temperatures below 30 degrees.

Visitors can see types of citrus they may not have seen or tasted, like the Rangpur lime (citrus x lonia), a hybrid between the mandarin orange and the citron. Among them also is the Tachinana mandarin (Citrus tachibana), which you wouldn’t want to bite into. The variety is believed to be more than a million years old. It’s bitter and barely edible, but monkeys in Japan love it.

There is also the Chinotto sour orange, a dwarf citrus perfect for small gardens that produces a sweet fruit, and Etrog citron, which produces a fruit used ritually during the Sukkot, the Jewish Feast of Tabernacles in the fall.

Visitors may see the Bearss lime, also known as the Persian lime or Tahitian lime, that most likely traveled to the Mediterranean through Persia and on to California via Tahiti.

And then there is the whole world of the “quats,” like the Marumi kumquat that produces delicious small round fruit and fragrant flowers and the Indio mandarinquat with its bell-shaped fruit with sweet, edible flesh.

Not all citrus is good for snacking, but many have skins that produce wonderful zests for cooking.

The five ancestral species for citrus are kumquat, micrantha, citron, pomelo and mandarin, which all beget the wonderful fruits we love from grapefruits and oranges to key limes, tangelos and more, all traced in an easy map in the exhibit.

It’s believed citrus traveled from Southeast Asia to Australasia, landing in the Americas in the 15th and 16th centuries with colonization and making its way indelibly into the cuisine.

The exhibit is part of a larger effort to revitalize the garden and bring in needed resources to keep the property viable, given the relatively modest endowment left by Jansen when she died more than 20 years ago.

“We haven’t really grown the other kinds of revenue sources that other cultural institutions do, so that’s the work,” said Medbury, who oversaw major capital campaigns during many years overseeing the storied Brooklyn Botanical Garden and before that, the San Francisco Botanical Garden and Conservatory of Flowers. “That’s the work and this is one idea, and kind of a fun idea.”

In 1997, Jansen did purchase an adjoining 22-acre ranch, which offers potential for the development of a California-native and pollinator garden that expands the mission of the garden and is more reflective of the current realities of climate change and Sonoma County’s natural summer dry climate .

“I started to get nervous we are not guaranteed the ground water we are presently pumping to that Asian garden and that we shouldn’t expand the footprint,” Medbury said. “We should really draw a line around it and keep it at that.”

You can reach Staff Writer Meg McConahey at 707-521-5204 or meg.mcconahey@pressdemocrat.com.