Planetrees are large, deciduous trees with buds covered by a single, closed scale. Axillary buds are hidden by the petiole base of a leaf. Terminal buds are absent. Leaves are alternate and lobed. Stipular scars leave a line around the stem when they are shed. Flowers are monoecious. Fruits are an aggregate structure comprised of hard-packed down and seeds. Down expands to assist in seed dispersal in the following spring.
Platanus 3acerifolia–London Planetree
Platanus occidentalis–American Planetree (Sycamore)
London Planetree–Platanus 3acerifolia
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| London Planetree |
A large tree maturing at 100 feet in height, the London planetree is reportedly smaller in dimensions than the American sycamore. This tree is an interspecific hybrid between the American sycamore and oriental planetrees. The London planetree is used extensively for ornamental, street, and park plantings. It has not been as useful in stressful urban sites as was originally suggested. London planetree is marginally cold-hardy in Ohio and is longer-lived when it is grown further south.
The trunk of the tree is straight, tall, and upright; the trunk carries a broad crown. Bark peels off in long strips or flakes, exposing light green or cream-colored new bark. Bark is blotched, or mottled, with sand, gray-brown, and green patches of older bark. The darker bark colors easily distinguish this tree from the American sycamore with its lighter-colored bark.
It usually has one, but there may be two to three, fruit heads in a cluster. The tree flowers in May. Fruit ripens in September to October, but the seeds are shed the following spring. The tree is attractive and conspicuous in winter with its mottled bark on the trunk and its button ball fruit hanging from the branches.
Leaves are 4—8 inches (10—20 cm) long with the middle lobe about as long as it is broad. Foliage has three to five lobes and is sparingly toothed. Leaves often have entire margins with the sinuses extending about one-third the length of the blade. The leaf base of the planetree is truncate, while the leaf base of the sycamore is normally cordate or auriculate.
The London planetree has a varied resistance to sycamore anthracnose and is generally more resistant to anthracnose than the American sycamore. The tree is often correctly labeled as disease resistant to this cosmetic disease. However, London planetree is more sensitive to cankerstain than the American sycamore. Cankerstain is normally fatal and is the disease which normally determines the life expectancy of the London planetree. London planetree is shorter-lived than American sycamore. Disease-tolerance does not mean that the tree is tolerant to all diseases.
American Planetree (Sycamore)–Platanus occidentalis
This tree, also called sycamore and buttonwood, is perhaps the largest hardwood tree in North America. It occurs throughout Ohio, reaching its larger sizes along streams and on rich bottom lands. Live streams are generally lined with sycamore in Ohio. It is a rapid- growing tree. At maturity it occasionally attains a height of 140—170 feet and a trunk diameter of 10—11 feet. The state champion is 129 feet tall, and 8 feet across with a 15-foot diameter trunk. This tree is the largest deciduous tree in the United States. The dimensions of this tree are given in Table 1 on page 5. Sycamores often fork into several large, secondary trunks, and the massive, spreading limbs form an open head sometimes 100 feet across.
The bark of this species is a characteristic feature. On younger trunks and large limbs it is very smooth and greenish-gray in color. The outer bark flakes off yearly in large patches and exposes the nearly white younger bark. The bark color of sycamore is much more showy than the London planetree. Near the base of old trees, the bark becomes thick, dark brown, and divided by furrows.
Twigs are glaucous and yellow-green to brown. Sycamore buds are covered by a single, closed scale. Axillary buds are hidden by the petiole base of a leaf. Terminal buds are absent. Stipular scars leave a line around the stem.
The leaves are simple, alternate, 4—7 inches (10—18 cm) long, and about as broad as they are long. Leaves are three-lobed, occasionally five-lobed, with shallow sinuses. The lobes are broader than long. Leaf margins are coarsely toothed or rarely entire. Foliage is light green and smooth above and paler below. The leaf base is cordate to auriculate and aids in separating this tree from the London planetree. The base of the leaf stalk is hollow, and in falling, exposes the winter bud.
Flowers are green and borne in May, and fruit ripens in September or October. The fruit is a ball about 1 inch (25 mm) in diameter and conspicuous throughout the winter as it hangs on its flexible stem which is 3—5 inches (71/2—13 cm) long. The fruit is a good identification feature as sycamore rarely has more than a single fruit per stem, while London planetree usually has several fruits per tree with two or three fruits per pedicel. During early spring, the fruit ball breaks up and the small seeds are widely scattered by wind and water.
The wood is hard and moderately strong, but decays rapidly in contact with the ground. It is used for butchers' blocks, tobacco boxes, furniture, and interior finish.
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| American Planetree (Sycamore) | ||