|Liriodendron tulipifera foliage and flower. Liriodendron chinense has more deeply lobed foliage and no orange pigment in its flower.
Morton Arboretum acc. 500-67*21
Liriodendron (pronounced /ˌlɪriɵˈdɛndrən/) is a genus of two species of tree in the Magnoliaceae family, known under the common name tulip tree (although it is unrelated to the tulip). Liriodendron tulipifera is native to eastern North America, while Liriodendron chinense is native to China and Vietnam. Both species are large deciduous trees. Various extinct species have been described from the fossil record.
The tulip tree is sometimes called "tulip poplar" or "yellow poplar", and the wood simply "poplar", although unrelated to the genus Populus. The tree is also called canoewood, saddle leaf tree and white wood. The Onondaga tribe calls it Ko-yen-ta-ka-ah-tas (the white tree).
Liriodendron are easily recognized by their leaves, which are distinctive, having four lobes in most cases and a cross-cut notched or straight apex. Leaf size varies from 8-22 cm long and 6-25 cm wide.
The Tulip Tree is a large tree, 18-32 m high and 60-120 cm in diameter. It is trunk columnar, with a long, branch-free bole forming a compact, rather than open, conical crown of slender branches. It has deep roots that are wide spread. 
Leaves are slightly larger in L. chinense but with considerable overlap between the species; the petiole is 4-18 cm long. Leaves on young trees tend to be more deeply lobed and larger size than those on mature trees. In autumn, the leaves turn yellow or brown and yellow. Both species grow rapidly in rich, moist soils of temperate climates. They hybridize easily, and the progeny often grow faster than either parent.
Flowers are 3-10 cm in diameter and have nine tepals — three green outer sepals and six inner petals which are yellow-green with an orange flare at the base. They start forming after around 15 years and are superficially similar to a tulip in shape, hence the tree's name. Flowers of L. tulipifera have a faint cucumber odor. The stamens and pistils are arranged spirally around a central spike or gynaecium; the stamens fall off, and the pistils become the samaras. The fruit is a cone-like aggregate of samaras 4-9 cm long, each of which has a roughly tetrahedral seed with one edge attached to the central conical spike and the other edge attached to the wing.
Liriodendron are also easily recognized by their general shape, with the higher branches sweeping together in one direction, and they are also recognizable by their height, as the taller ones usually protrude above the canopy of oaks, maples, and other trees—more markedly with the American species. Appalachian cove forests often contain several tuliptrees of height and girth not seen in other species of eastern hardwood.
In the Appalachian cove forests, trees 150 to 165 feet in height are common, and trees from 166 to nearly 180 feet are also found. More Liriodendron over 170 feet in height have been measured by the Eastern Native Tree Society than for any other eastern species. The current height champion is approximately 178.5 feet in height and grows along Baxter Creek in the Great Smoky Mountains National Park. The tallest tulip trees on record probably reached 190 feet in height, taller than any other eastern hardwood. Today the tulip tree is rivaled in eastern forests only by white pine, loblolly pine, and eastern hemlock. There are reports of tulip trees over 200 feet in height, but none of the measurements have been confirmed by the Eastern Native Tree Society. Most reflect measurement errors attributable to not accurately locating the highest crown point relative to the base of the tree—a common error made by the users employing only clinometers/hypsometers when measuring height.
Maximum circumferences for the species are between 24 and 30 feet at breast height, although a few historical specimens may have been slightly larger. Today the Great Smoky Mountains National Park has the greatest population of tulip trees 20-feet and over in circumference. The largest-volume tulip tree known anywhere is the Sag Branch Giant, which has a trunk and limb volume approaching 4,000 cubic feet (110 m3).
Liriodendron has been reported as fossils from the late Cretaceous and early Tertiary of North America and central Asia. It is known widely as Tertiary age fossils in Europe and well outside its natural range in Asia and North America, showing a once circumpolar distribution. Like many "Arcto-Tertiary" genera, Liriodendron apparently became extinct in Europe due to large-scale glaciation and aridity of climate during glacial phases.
Liriodendron sp. prefer a temperate climate, sun or part shade and deep, fertile, well drained and slightly acidic soil. Propagation is via seed or grafting. Plants grown from seed may take more than eight years to flower. Grafted plants will flower earlier depending on the age of the scion plant.
North American Tulipwood is fine grained and stable. It is easy to work and commonly used for cabinet and furniture framing, i.e. internal structural members and sub-surfaces for veneering. Additionally, much inexpensive furniture, described for sales purposes simply as 'hardwood,' is in fact primarily stained poplar. In the literature of American furniture manufacturers from the first half of the 20th century, it is often referred to as 'gum wood.' The wood is only moderately rot resistant and is not commonly used in shipbuilding but has found some recent use in light craft construction. The wood is readily available and when air dried has a density of approximately 24 pounds per cubic foot (0.38 g/cm3).
The name canoewood probably refers to the tree's use for construction of dugout canoes by Eastern Native Americans, for which its fine grain and large trunk size is eminently suited.
Liriodendron 'Chapel Hill' and 'Doc Deforce's Delight' are hybrids of the above two species
L. tulipifera 'Ardis' is a small-leaf, compact cultivar that is rarely seen
L. tulipifera 'Aureomarginatum' is variegated with yellow-margined leaves
L. tulipifera 'Fastigiatum' grows with an erect or columnar habit (fastigiate)
L. tulipifera 'Glen Gold' bears yellow-gold colored leaves
L. tulipifera 'Mediopictum' is a variegated cultivar with gold-centered leaves
~ Tulip Tree
Classification System: APG II (down to family level)
Species: L. chinense - L. tulipifera
Liriodendron L., Sp. Pl. 1: 535. 1753.
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