tree was introduced into southern Florida in the early 1900s for swamp drying. Having no natural enemies, it spread aggressively, crowding out the native vegetation that is essential for supporting animal life. Now, the cajeput poses a serious environmental threat to the Everglades and other expanses of southern Florida, where it is growing explosively, turning the natural grassy wetlands into dense melaleuca thickets. Biological control is now offering hope, however. The U.S. Department of Agriculture is releasing several species of Australian snout beetles, which are specific to melaleuca and feed on its shoots, reducing the plant’s ability to reproduce.
Aesculus californica
CALIFORNIA BUCKEYE
LOCATION: 2694 McAllister St./Willard St. N. near the University of San Francisco campus; also at 124 Lower Terrace/Levant St. in the Upper Market neighborhood
This is one of the few trees in this book that is a true San Francisco native, existing within the current city limits before the arrival of Europeans. The California buckeye also is one of the state’s most beautiful native trees, growing to 20 feet in height on wind-protected sites in the dry slopes and canyons of the coastal range and Sierra foothills. The tree produces showy, long-lasting clusters of white flowers in May and June. One or two pear-shaped fruits form on each flower cluster, and inside each fruit’s leathery jacket is a seed with a shiny brown coat. The tree’s light green leaves are divided into five to seven leaflets, which drop in July (an adaptation to long, dry summers) unless summer water is provided.
American Indians crushed this tree’s poisonous seeds and added them to dammed-up streams to stupefy fish, making them easy to catch. (Today you may find California buckeyes near old Indian campgrounds.)
Perhaps because of its spreading form, the California buckeye is rarely planted as a street tree in San Francisco, due to narrow urban setbacks. You can view a large and spectacular specimen in a yard at 2694 McAllister Street, near the University of San Francisco campus. The tree was scheduled for removal in 1999 in connection with new construction on the lot, but after a neighborhood outcry, plans for the house were changed to build around, and preserve, the tree. As part of the settlement, the property owner signed a tree easement with Friends of the Urban Forest, protecting the tree from future removal—and making this the only tree in the city protected by a contract.
Schinus molle
CALIFORNIA PEPPER TREE
A mature California pepper arching over a backyard patio is a cliché of Sunset magazine’s California lifestyle. Cliché or not, the California pepper is one of the most beautiful trees available to San Francisco tree lovers. Mature peppers have wonderfully gnarled trunks, supporting rounded crowns of graceful, arching branches. The fernlike foliage is finely textured, with bright green leaves composed of many leaflets. California peppers have either male or female flowers; female flowers develop into drooping clusters of showy rose-colored peppercorn berries in the fall and winter. The seeds are sometimes sold as pink peppercorns, although in large quantities they can be toxic. (To avoid messy fruit drop, many city dwellers plant trees with male flowers only.) Like its relative the Brazilian pepper, this tree is related botanically to mangos, pistachios, and cashews, as well as to poison ivy and poison oak; contact with its leaves can cause dermatitis or allergic reactions in some individuals. Despite its common name, this tree is native not to California but to the Andes Mountains in Peru (in fact, many sources now use Peruvian pepper tree as the common name). It has, however, become naturalized in chaparral areas of Southern California.
LOCATION: 4019 26th St./Sanchez St. in Noe Valley
Pyrus calleryana
CALLERY PEAR
Two cultivars of callery pear are common on San Francisco streets. ‘Aristocrat’ is most common and has a rounded form. ‘Chanticleer’ has a more upright form. Each variety has dark green, glossy leaves that, in hotter climates, turn showy reds and scarlets in the fall. But with few exceptions we get only greens and yellows in cool, foggy San Francisco (I’ll admit that I chose one of the exceptions for the photo at right). The tree is bare November–March, although individual trees can differ significantly in this aspect. Flowers appear in March, but in San Francisco this tree is not planted for its flowers, because it does not bloom well in the city’s mild climate. (Hmm … no flowers, disappointing fall color … I will reveal some personal prejudice and say I am not a fan of this tree in San Francisco.) Flowers are often followed by a few inconspicuous clusters of round, pea-sized, green or brown pears hidden amid the foliage. This fast-growing tree (particularly the ‘Aristocrat’ cultivar) reaches heights of 25–35 feet. Callery pear is native to China and Vietnam.
LOCATION: 239 Connecticut St./18th St. on Potrero Hill; also 436 Cole St./Fell St. in the Haight-Ashbury
Phoenix canariensis
CANARY ISLAND DATE PALM
Years ago, I didn’t associate palm trees and San Francisco. Los Angeles, sure, but San Francisco? Since the early 1990s, however, Canary Island date palms have been used extensively in high-profile street-landscaping projects in San Francisco. In 1993, the tree was used to line the entire length of upper Market Street, to spectacular effect. In the late 1990s, Canary Island date palms were planted at the city’s waterfront along the Embarcadero, from AT&T Park all the way to Fisherman’s Wharf, replacing the elevated freeway that formerly cut off the city from its bay views. Plenty of San Franciscans complained at the time, concerned that the palms were “Los Angelizing” the city. Fortunately, they lost that aesthetic battle, and the stately Canary Island date palm is now very much part of the San Francisco fabric.
The Canary Island date palm supposedly was introduced to California by Spanish mission priests during the 18th century. The tree has a massive trunk, 4–5 feet in diameter, which in its natural state is roughened by the woody remnants of old palm fronds. In cultivation, the trunk is usually trimmed to a smooth cylinder. The gracefully arching leaves are 15–20 feet long, with 2-inch-wide leaflets measuring 12–16 inches long. Cream-colored flowers appear in clusters, with male and female flowers on different trees; the female trees produce (inedible) clusters of datelike ¾ -inch seeds in the fall. The tree is native to Spain’s Canary Islands, in the Atlantic off the southwest coast of Morocco.
LOCATION: Corner of Dolores St. and 20th St. in the Mission; many other specimens in the Dolores St. median intermixed with other palm species
Ceratonia siliqua
CAROB
This tree has biblical roots. It is said that the foot-long, brown, leathery fruit pods of the carob tree were the “locusts” that St. John the Baptist survived on in the wilderness in the Gospel of Mark. The pods are also thought to be the “husks” that tempted the prodigal son in the New Testament parable.
Rich
