[PHOTOSET] An Unlikely Wilderness: Meet San Francisco’s Urban Forest

SAN FRANCISCO — On Tuesday, Wilderness Press released the second edition of Trees of San Francisco by Mike Sullivan. The first edition, published over 10 years ago, was widely acknowledged for its appeal to the general public, cutting out most scientific and botanical jargon. More a travel guide than a field guide, Trees of San Francisco is designed to introduce the reader to what’s interesting about one of America’s most unique urban forests.

From the introduction to Trees of San Francisco:


Trees can have a hard time in San Francisco. Before the arrival of the Spanish to the Bay Area in the late 18th century, San Francisco was largely treeless. Only a few live oaks and willows huddled in wind-sheltered valleys interrupted the expanse between the San Francisco Bay and the Pacific Ocean. In fact, according to historian Hubert Bancroft, the Spanish explorers described the area as “the very worst place [for settlement] in all California… since the peninsula afforded neither lands, timber, wood, nor water, nothing but sand and brambles and raging winds.”

Small Leaf Tristania

Small Leaf Tristiana, the 2nd most planted tree in San Francisco, acc. to Friends of the Urban Forest

San Francisco’s urban forest is a relatively recent phenomenon. Early tree-planting efforts focused almost exclusively on public parks. Beginning in 1870, the creation of Golden Gate Park out of acres of sand dunes was the most ambitious of these efforts… Despite early successes creating tree-filled parks, San Franciscans left their streets bare for many more years. Look at any photograph of the city’s neighborhoods as recently as the 1960s, and the lack of trees will be striking. Things began to change in the late 1960s and 1970s when San Francisco (a center of the growing environmental movement) began city-sponsored street tree plantings in the neighborhoods.

City arborists involved with the new program had to learn, through trial and (frequently) error, which trees would thrive in San Francisco’s unique climate and topography. Early tree-planting efforts focused on a very few trees (ficus, blackwood acacia, Myoporum, and others) selected for their rapid growth rates and tolerance of coastal conditions. Unfortunately, many of these fast-growing trees quickly developed into “green monsters” that buckled sidewalks, crowded narrow street setbacks, and (unforgivable in San Francisco) blocked views.

In 1981, things took a turn for the worse, as a municipal budget cut eliminated tree-planting programs in most of the neighborhoods. Tree-hugging residents responded by forming Friends of the Urban Forest (FUF), a volunteer-based nonprofit organization, to step into the breach and continue the greening of San Francisco. In addition to the energy and enthusiasm of its volunteers, Friends of the Urban Forest offers growing expertise in recommending tree species appropriate for the city. That expertise is important because of the unique geographic and climatic conditions that make San Francisco a challenging environment for trees.

As a result, San Francisco trees have to be able to handle:

  • sandy soils set in cement
  • driving wind
  • foggy summers
  • seven months a year without rain
  • attacks from view-conscious residents

It’s hardly a place for maples and beeches. But through decades of trial and error, San Franciscans have discovered and welcomed a unique mix of trees from around the world that thrive in our unusual conditions.


Here are the top 5 most planted trees in San Francisco, according to FUF data:

Strawberry Tree1: Strawberry Tree

The Strawberry Tree, also known as Arbutus ‘Marina’, is one of the few trees to flower in the fall, covered in clusters of small cream-colored lanterns resembling lilies-of-the-valley. The fruit is edible, resembling actual strawberries, but is more pleasant for birds than humans to eat. Arbutus ‘Marina’ is a hybrid of uncertain origins, but one of its parents is likely Arbutus unedo, a European native that is also planted occasionally on SF streets. The Portuguese call this tree medronho, which is also the name of the liqueur they distill from its fruits.

Arbutus ‘Marina’ has a renowned history with San Francisco, first introduced to the area in 1984 by the Saratoga Horticultural Foundation. Famous San Francisco horticulturist and plant breeder Victor Reiter boasted the world’s oldest Strawberry Tree until 2006. His tree was planted in 1933.



 Small Leaf Tristania2: Small Leaf Tristania

The Small-Leaf Tristania, Tristaniopsis laurina, may be San Francisco’s most successful small street tree. Growing 20-25 ft. in height, the tree is a tough, hardy tree, resistant to disease, pests and tolerant of poor soils, wind and poor climate conditions. The Small-Leaf is a great tree for those without a green thumb.








Japanese Flowering Cherry3: Japanese Flowering Cherry

Known scientifically as Prunus serrulata, or ‘The Kwanzan,’ the Japanese Flowering Cherry is one of the most popular trees in San Francisco. In April, this cultivar blooms with showy pink double flowers, which resemble pom-poms, in large clumps along the stem. The Kwanzan cultivar is also sterile, however, bearing no fruit. The tree is bare from December-March, and the bark is also distinctive: thin, smooth, and reddish brown, with prominent horizontal lenticels.






Southern Magnolia4: Southern Magnolia

Native to the Southeastern United States, the tree can reach 25-45 ft. in height. Its leaves are a waxy, glossy green, with large, white flowers that bloom in March. The Magnolia tree predates the evolution of butterflies and traditional pollinators. The magnolia’s primitive mystique is enhanced by its unchanged method of pollination by beetles.

Fossil records suggest that magnolias were found throughout the Northern Hemisphere before the glacial period of the most recent ice age. As the Earth’s climate cooled and glaciers advanced, the species was forced southward.





 Purple Leaf Plum5: Purple-Leaf Plum

Purple-Leaf Plum, or Prunus Cerasifera, is one of the first of the flowering trees to bloom. The Purple-Leaf Plum produces showy light pink flowers in late January or February. The purple leaves emerge shortly after the flowers fade.









Live in a metropolis? What sort of urban forestry has your community undertaken? Let us know in the comments.

If you’re in the Bay Area, be sure to check out this new edition of Mike Sullivan’s Trees of San Francisco, available now online and in stores. Don’t forget that purchases direct from WildernessPress.com will save you 25% instantly!

(All photos — including feature photo — courtesy of Mike Sullivan, FUF, and Wilderness Press.)

Trees of SanFran 2ed lo-res

About Mike Sullivan

Mike Sullivan has a long-standing interest in San Francisco’s trees. A 30-year resident of the city, he is a member and past president of the board of directors of the nonprofit Friends of the Urban Forest, and leads frequent neighborhood tours for that organization. Sullivan is a past member of the San Francisco Recreation and Park Commission, as well as the city’s Urban Forestry Council. He lives in the well-forested Parnassus Heights neighborhood of San Francisco.

About Trees of San Francisco, 2nd edition

The Trees of San Francisco beckons residents and tourists alike to enjoy the city from a new perspective, beyond the bridges and cable cars. Author Mike Sullivan acquaints readers with the trees in a reader-friendly manner. The book features 64 of San Francisco’s most common and interesting trees, as well as color photographs and the best places to view the trees. It also includes 13 sidelights (discover the favorite trees of the city’s wild parrots) that provide touches of local color. To boot, Sullivan guides you through 12 enjoyable walking tours, including easy-to-use, full-page color maps. Finally, Sullivan groups San Francisco’s best trees and their locations within 23 selected neighborhoods.

Tanya Twerdowsky

I am a Jersey girl living in Alabama who loves to run far and eat lots.

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