Tuesday, February 28, 2017
London Planetree- plantanus x acerfolia
The London Planetree- plantanus x acerfolia - is a hybrid of the Sycamore and the Oriental Plane. London Planetree are large deciduous trees that reach heights of 65-100 feet when mature. It is one of the most commonly planted street trees in the United States because of it's high tolerance to both polluted air and limited rooting areas. It possesses a very strong hybrid vigor and grows well in almost all locations, but is not very tolerant to extremely low temperatures. It has a fairly long life expectancy and in many cases "outgrows" it's location by lifting sidewalks and other surrounding obstacles. Thought to have been originally grown in Spain during the very early 17th century. It is recorded in both France and Spain around 1650, and in England from 1680.
The leaves are very similar in shape to the Maple with a tri-lobed appearance. They are a bright green color when young and are coated with very tiny hairs which disappear by the Summer season. In the fall the leaves slowly turn to a bright yellow color before falling off. The bark is almost identical to the Sycamore in appearance, smooth Silver Grey that sheds to show a warm brown shade underneath. The bark makes for a nice point of interest even in the winter when the leaves are all gone. The lumber is known as Lacewood and has a very unique and decorative pattern when cut, it is light in color with dark red-brown flecks throughout. The flowers are borne in one to three dense spherical florescence on a pendulous stem, with male and female flowers occurring on separate stems. The fruit matures in about 6 months, to just under a half inch in diameter, and is made up of a dense spherical cluster of achenes with numerous stiff hairs. The fruit cluster breaks up slowly over the winter to release the numerous 2–3 mm seeds, this allows for great seed disbursement.
Image Citation (Photos 1-3): Tom DeGomez, University of Arizona, Bugwood.org
One of the diseases that has known to significantly effect London Planetrees is Cankerstain. Thousands of London Planetree have died from Cankerstain in the Eastern United States since the early 1930's. Cankerstain is caused by the fungus Ceratocystis fimbriata. The fungus enters the trunk or branches through weakened areas such as injuries, or saw cuts and moves inward from there. Once infected death of the entire tree usually occurs within a year or two. Diseased trees should be removed and destroyed as soon as diagnosed to prevent spread. The London Planetree is also succeptable to Lacebug, Plum Borer and Anthracnose to name a few.
London Planetrees are often pruned using a technique called pollarding. A pollarded tree has a very noticeably different appearance than an unpruned tree, it will appear much shorter with stunted, clubbed branches. Pollarding requires frequent maintenance (the process must usually be repeated annually), it creates a distinctive shape that is often sought after in plazas, parks, main streets, and other urban areas where overall size and appearance is of great concern.
London Planetree can be found at most local nurseries and is recommended 3A to 10B. It is very important to plan ahead before planting a London Planetree, take into consideration how big it will be at maturity- 65-100 feet tall in very large!