Conestoga House & Gardens, 1608 Marietta Avenue, Lancaster PA
The very top of this tree has a Witch’s Broom. In this type of deformity, the natural structure of the tree is changed by having a dense mass of shoots growing from a single point. The re- sulting structure resembles a broom or a bird’s nest.
Caused by fungus, mites, nematodes, viruses or bacteria, brooms are a rich source of new cultivars when parts are collected and later grafted. This is because the attacking organism can sometimes actually change the inheri- ted growth pattern of the twigs. Brooms thus provide the genetic source for many landscape plants sold at nurseries.
The amazing species (T. canadensis) is incredibly long-lived and can reach 1,000 years.