The Trees of San Francisco. Michael Sullivan
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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 in sugar and protein, the carob’s pods can be milled to a fine powder for use as a chocolate substitute. Within the pods, the carob seeds are of remarkably uniform weight, and ancient Mediterranean civilizations used them as a unit of measure to weigh gems and other precious substances (the Arabic word for the carob seed was quirat , from which our word carat originates). You will rarely see the pods or seeds of the carob in San Francisco, because only female trees produce them (11 months after pollination), and the females are seldom planted on city streets.
LOCATION: Northeast corner of 22nd and Dolores Sts. (on Dolores) in the Mission; also at 850 Florida St./20th St. in the Mission and at 957 Cole St./Parnassus Ave. in Cole Valley
Female seedpod
The carob is a native of the eastern Mediterranean. It grows to 30 feet, with a dense, rounded crown. This is a tree to plant for its foliage. The glossy, dark green leaves are beautiful and distinctive, with each compound leaf divided into 4–10 round leaflets. Small, inconspicuous red flowers form in spring. Not surprisingly, given its desert origin, the carob is very drought tolerant. A drawback: Carobs have extremely invasive roots, and mature trees will cause significant sidewalk damage.
Our Wild Parrots and Their Chosen Trees
AMONG San Francisco’s quirky charms is a flock of wild parrots—estimated at more than 200 birds. The parrots roost in Sue Bierman Park, formerly called Ferry Park, near the Embarcadero. The birds are red-masked conures, native to Ecuador and Peru, and are the offspring of pets that escaped in the late 1980s and early 1990s. With brilliant green bodies and red heads, they have become something of a tourist attraction in San Francisco.
The parrots make Sue Bierman Park their home because of its tall Lombardy poplars (Populus nigra ‘Italica’). These trees offer good perches, with great visibility—helping the parrots watch for hawks, their most common predator. During breeding season, the birds like to nest in Canary Island date palm trees (Phoenix canariensis). When this palm’s fronds break off the trunk, a small hole or indentation is often created. With a little industrious digging, the parrots can turn these spots into perfect nesting holes.
During most of the year, the flock rarely leaves the city’s northeast quadrant, an area ranging from the Ferry Building environs to Telegraph Hill, Russian Hill, North Beach, Fort Mason, and the eastern edge of the Presidio. But as tree fruits begin to ripen in less dense parts of the city during the summer and fall, the parrots make an annual trek to the Castro, Cole Valley, and other neighborhoods to the south and west. They seem to know exactly when and where to visit.
During summer months, plum trees on the streets and in the backyards of these neighborhoods beckon the parrots. Even though the city discourages planting fruit-bearing trees on the streets, in July and August many backyard specimens fill with ripe plums—irresistible to the parrots. They perch in the trees, methodically grabbing the fruit and eating it from the tight grasp of their claws. Another parrot favorite is the English hawthorn tree (Crataegus laevigata), whose fruit also ripens in July and August.
At our home in Parnassus Heights, we have a backyard pippin apple tree (Malus domestica), and we know that, come October, we have to harvest it before the parrots do. They have figured out exactly when the apples ripen, so we count on their annual fall visits, when they strip the tree of the apples we can’t reach.
The parrots typically travel