The Trees of Foothill Boulevard – The London Planetree

Foothill Boulevard is a wide, rather barren street and its dominant features are small businesses and shopping malls fronted by a hodge-podge of architectural styles. There is little greenery, but that is beginning to change.

Decades ago an effort was made to add some green to the street with the planting of crepe myrtle trees in the parkways, but for some reason they never reached their full height and have remained for the most part stunted. Some even died, leaving empty dirt places in the sidewalk. About 10 years ago the Crescenta Valley Town Council reached an agreement with the County of Los Angeles to plant new trees in the empty planter holes in the County portion of Foothill, from Briggs Avenue to Pennsylvania. The London planetree was selected and has done very well. Many of them have gotten quite large, for instance in front of the former OSH building. When the medians were put in last month, the London planetree was again selected as the dominant tree, along with others. But what is a London planetree?

The name is confusing. Was the tree originally native to the great American plains around London, Kansas (population 774)? Is it derived from a ’60s rock band name, like Jefferson Airplane?

The “plane” refers to the tree genus platanus, a worldwide family of trees that embraces the many varieties of sycamore, including our own Western sycamore, numerous in Verdugo Park. Platanus is derived from the Ancient Greek platus, a descriptive word meaning wide or broad, which does indeed describe the wide spreading branches of the planetree.

The London plane is actually a hybrid, a cross between an Oriental plane, which grows in Eastern Europe and the southern part of Asia, and the American sycamore, native to the eastern U.S. Its hybridization history is murky, probably even accidental. In the 17th century, the naturalist movement (the study of nature and biology) was strong in the great colonial powers of the world: England, France and Spain. As these great nations spread across the world, naturalists collected specimens to bring back to London and Paris, including plants and trees that were planted together in great botanical gardens. It’s generally thought that an Oriental plane from eastern Europe and an American sycamore from the New World were planted too close to one another and cross-pollinated, resulting in a hybrid between the two. By 1700, this vigorous hybrid was being planted in the great cities of Europe. As the Industrial Age took hold, many cities, particularly London, became choked with coal smoke, so much so that some native trees died. But the hybrid proved resilient to pollution, and became the dominant street tree in London, thus gaining the name London plane.

The trees’ resistance to pollution is quite simple. All trees have “pores” in their trunks that, in a sense, “breathe” (highly simplified). If those pores are clogged by soot or road dust, the tree suffers. The London plane sheds the bark that has become clogged as it grows exposing fresh pores beneath. This results in the pleasing dappled appearance of the trunk, looking somewhat like military camouflage. In fact the dominant German camo pattern in WWII was called “Plane Tree Camo” or platanentarn in German.

History aside, the London plane is the most popular street tree in cities across the world. They have a resistance to pollution and dust, and do well with the root compaction that happens on streets and sidewalks. London planes are wind resistant as well, a must for the foothills. They are fast growing, and will get quite tall, 60 to 100 feet, with branches that start high up the trunk so as to not block business signs. They much resemble our native sycamores except that they grow straight up rather than spreading laterally. And we must remember that, just like our native sycamores, they are deciduous. Those newly planted London planes in the medians that look like dead sticks will take off come spring, and will quickly grow beautiful and magnificent. Given time to grow, they will make Foothill Boulevard a green parkway.