Strolling across the Marin woodlands where his forebears once lived, Philip Gerstle handed out shovels to his cousins.

They gathered for a tree planting during an Aug. 10 family reunion. This was no casual affair. More than 200 people, with last names like Lilienthal, Fleischhacker, Levison, Mack and Gerstle, had come together at San Rafael’s Gerstle Park, named for the family patriarch.

Aside from the tree planting, the cousins spent most of their time shmoozing at the site where the Gerstles, who had made a fortune in the Alaskan fur trade, built their 19th-century Shangri-La.

Though the old family mansions, stables and cottages are long gone, Gerstle Park is where the descendants gather and remember.

“In past [reunions] we had people stand up and tell childhood stories,” Gerstle said, referring to tales of family patriarchs and matriarchs, all of whom died many decades ago. “But there’s nobody left who knew them.”

The tree planting had added symbolic value. An updated family tree, unscrolled at the reunion, included more than 850 names, going back to Lewis Gerstle (1824-1902), the German Jewish immigrant whose rags-to-riches tale exemplifies the American dream.

Philip Gerstle, 70, has met hundreds of his cousins at reunions over the years, a tradition that started in 1957. He’s attended them all, including the previous one in 2001. Today he lives in Arcata in Humboldt County, but he grew up in San Francisco, the great-great-grandchild of Lewis and Hannah Gerstle.

Another great-great-grandson, David Fleishhacker, 77, is descended from Bella Gerstle, the last of Lewis and Hannah’s seven children.

Fleishhacker lives in Woodside near Green Gables, the 75-acre property his paternal grandfather bought early in the last century. But he gladly shlepped to San Rafael for the reunion.

“It’s unusual for a family to keep up these connections,” said the retired schoolteacher and former headmaster of the Burke School in San Francisco. “The Internet made it possible for a family to have a picnic like this.”

Fleishhacker is a walking genealogical encyclopedia. He knows countless facts about the clan, and has in his possession a leather-bound photo album filled with sepia-toned pictures, some of which go back more than 150 years.

One stands out: a young Lewis and Hannah Gerstle, glumly posing sometime in the 1850s, just as their American fairy tale began to take shape.

Lewis Gerstle came to America from Bavaria in 1845. Penniless at first, he worked his way to California in 1850, just in time for the Gold Rush. He opened a Pony Express in Sacramento and, later, a grocery store with a fellow German Jew, Louis Sloss.

In time the partners expanded their business, opening a San Francisco brokerage house. The two also married a pair of sisters, Hannah and Sarah Greenebaum.

Their fortunes really took off around 1870 after the United States acquired Alaska from Russia. That led to a multi-million-dollar contract for dry goods stores and rights to the seal fur trade. After gold was discovered in the Klondike in 1895, the partners’ Alaska Commercial Company was worth millions.

Though prosperous San Franciscans (the two patriarchs lived in adjoining Victorian mansions on Van Ness Avenue), the Gerstles and the Slosses still faced discrimination because of their Jewish roots. After being turned away from the then-restricted town of Santa Cruz, in 1881 the families bought a 4.6-acre parcel in San Rafael nicknamed Violet Terrace. Purchase price: $15,000.

There the Slosses and Gerstles built three homes (36 bedrooms, 16 baths) amid vineyards, orchards and a pavilion in the redwoods.

After Lewis Gerstle died in 1902, the Alaska Commercial Company was sold off. Following his wife’s death in 1930, the family donated the grounds of Violet Terrace to the city of San Rafael. No original structures remain.

The children and grandchildren married into other prosperous Jewish families. Most branched out into building up San Francisco as America’s West Coast financial powerhouse, with inroads in banking, insurance and business. Most belonged to Congregation Emanu-El, according to Fleishhacker, and Fleishhacker’s father served as president of the synagogue. Many other members of the clan moved to Los Angeles or out of state.

Some local family members became patrons of the arts, such as Will Gerstle, an early supporter of the San Francisco Museum of Modern Art. Bella Gerstle (Fleishhacker’s grandmother) was a painter and an early patient of Carl Jung (she traveled to Switzerland for her sessions with the famed pioneer of psychology).

Back at the family reunion, Philip Gerstle noted that 100 of the people represented on that unfurled family tree are under the age of 20. That fact, he felt, would keep the extended Gerstle family going far into the future.

“I think it’s important,” Gerstle says of the reunion, which he helped organize. “Otherwise I wouldn’t be taking this on right now.”