Taxonomy and Botany of Tulip Trees
Plant taxonomy classifies tulip trees as Liriodendron tulipifera. For their common name, you will also find "tulip poplar" and "yellow poplar," perhaps because their leaves shake in the breeze a la poplar leaves (you have probably heard of "quaking" aspens, known botanically as Populus tremuloides). Nonetheless, they are not in the Populus genus at all, being more closely related to magnolias.
Liriodendron tulipifera plants are deciduous trees.
Characteristics of These Trees
Indigenous to eastern North America, tulip trees reach 90 feet or more in height. They are tall and straight-trunked, with a canopy width somewhat less than 1/2 their height at maturity. The branches begin rather far up the trunk and are often arranged symmetrically. Tulip trees can be identified by the shape of their leaves: the concavity at the tips of the leaves (or where one would expect a typical tip) suggests that someone came along and took a bite out of them. Their leaves provide yellow to golden fall foliage.
The flowers that give tulip trees their name are yellowish-green, with a touch of orange on the outside. Bloom time is late spring. The cone-like fruit that they leave behind also offers some ornamental value.
Sun and Soil Requirements, USDA Plant Hardiness Zones
is best grown in planting zones 5-9.
Landscaping Uses, Cultivars and Varieties
These giants function in the landscape as fast-growing shade trees with fall-foliage interest. As is often the case, the trade-off for their fast growth is relatively weak limbs, which can create a hazard in storms.Their showy flowers make them something of an anomaly among really tall shade trees in Northern regions.
But the Ohio State University (OSU) Extension notes that "often the tree does not flower until it reaches at least 15 years of age, and even then only sparsely in the uppermost reaches of the tree, making the upright-held flowers more difficult to notice and appreciate," adding that "older trees flower heavily and their lowermost branches become pendulous, allowing for visualization of the beautiful flowers up-close."
Michael Dirr lists available cultivars and varieties (Dirr's Encyclopedia of Trees & Shrubs, Page 454). Here are some that he mentions; noteworthy features appear in parentheses:
- 'Ardis' (only 30 feet tall)
- 'Aureomarginatum' (variegated leaves)
- 'Fastigiatum' (a columnar form that Dirr compares to Lombardy poplar)
- 'Tennessee Gold' (a yellow-leaved cultivar)
Due to the following facts, some people may judge tulip trees best suited to large properties, where homeowners are fostering woodland gardens, perhaps:
- They can be messy trees for homeowners, as their flower petals will "litter" the area below just after blooming.
- The aphids that the tree attracts also make a mess, with their honeydew secretion.
- Some leaves will turn yellow and drop prematurely during dry summers, because tulip trees do not tolerate drought very well.
- They should not be planted near homes in regions prone to hurricanes.
- Their shallow root system makes these trees difficult to plant under.
Plant Care, Wildlife Attracted by Tulip Trees
According to the OSU Extension, the tulip tree "is extremely sensitive to being transplanted in the Autumn." The same source recommends that, should it be necessary, nonetheless, to transplant in fall, you should take extra pains "to amend the soil, fertilize, water thoroughly, mulch adequately, and avoid Winter salt spray."
Hummingbirds are drawn to the nectar in the flowers, while bobwhites, rabbits, squirrels and other animals feed on the seed.
Origin of the Names and Avoiding Confusion
There is something of a discrepancy in the scientific name, Liriodendron tulipifera. Composed of the Greek words for "lily" and "tree," the genus name, Liriodendron suggests that the flowers resemble lilies.
One is tempted to ask, then, "Which is it: do tulip trees' blooms look like lilies or tulips?" Considering that we commonly call these giants "tulip trees," the specific epithet, tulipifera may carry more weight: tulipifera is Latin for tulip-bearing, referring to the flowers' appearance. Even the leaves could also pass for two-dimensional representations of opened tulips.
Do not confuse American tulip trees with the unrelated African tulip trees, Spathodea campanulata. Whereas the latter is a tropical plant known for its flowers, the former is a plant of the temperate zones valued as a fall foliage tree.