Platanus x acerifolia

American sycamore (P. occidentalis) is in the plane tree or Plantanaceae family. It has been quite susceptible to a fungal disease, so has been cross-bred with the more resistant Oriental plane (P. orientalis), resulting in the hybrid London plane (P. x acerifolia) which is now most commonly used as a species of choice horticulturally. However, American planes have survived well in the Mediterranean climate along the West Coast, occasionally reaching up to 2 meters or more in diameter.

• Leaf is simple, alternate, palmately veined, 10–23 cm long, three to five-lobed by broad shallow sinuses rounded in the bottom. In summer, buds are completely hidden by the bases of the petioles.
• Species is monoecious. Flowers appear in May along with the leaves in dense heads. Female (staminate) and male (pistillate) heads are on separate stems (peduncles). The staminate heads are dark red, on auxiliary peduncles; pistillate heads are light green tinged with red, smaller and more plentiful, on longer terminal peduncles.
• Fruit forms seed balls (achenes) 2.5 cm in diameter, normally 2 per stock, which hang on stems 7 to 14 cm long which remain on the tree over the winter.
• Twigs are zigzag; leaf scars completely surround the twig; buds are conical.
• Bark is exfoliating, separating into thin plates which peel off and leave the surface pale yellow, or white, or greenish.