| Liriodendron | |
|---|---|
 | |
| Liriodendron tulipifera foliage and flower. Morton Arboretum acc. 500-67*21 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Magnoliids |
| Order: | Magnoliales |
| Family: | Magnoliaceae |
| Genus: | Liriodendron L. |
| Extant species | |
| |
Liriodendron (/ˌlaɪriəˈdɛndrən,ˌlɪr-,-ioʊ-/[2][3]) is a genus of two species of characteristically large trees,deciduous over most of their populations, in the magnoliafamily (Magnoliaceae).
These trees are widely known by the common nametulip tree ortuliptree for their large flowers superficially resemblingtulips. It is sometimes referred to astulip poplar oryellow poplar, and the wood simply as "poplar", although not closely related to the truepoplars. Other common names include canoewood, saddle-leaf tree, and white wood.
The twoextant species areLiriodendron tulipifera,native to easternNorth America, andLiriodendron chinense, native toChina andVietnam. Both species often grow to great size; the North American species may reach as much as 58.5 m (192 ft) in height.[4] The North American species is commonly usedhorticulturally, the Chinese species is increasing in cultivation, andhybrids have been produced between these twoallopatrically distributed species.
Various extinct species ofLiriodendron have been described from the fossil record.
Liriodendron trees are easily recognized by theirleaves, 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. They are deciduous in the vast majority of cases for both species; however, each species has asemi-deciduous variety at the southern limit of its range inFlorida andYunnan respectively.[5] The tulip tree is often a large tree, 18–60 m high and 60–120 cm in diameter. The stoutest well-authenticated Tulip tree was the Liberty Tree inMaryland which was 21.5 feet (6.6 meters) in circumference.[6] It died in 1999. The tree is known to reach the height of 191.8 feet (58.5 meters),[7] in groves where they compete for sunlight, somewhat less if growing in an open field. Its trunk is usually columnar, with a long, branch-free bole forming a compact, rather than open, conical crown of slender branches. It has deep roots that spread widely.[8]
Leaves are slightly larger inL. chinense, compared toL. tulipifera, but with considerable overlap between the species; thepetiole is 4–18 cm long. Leaves on young trees tend to be more deeply lobed and larger in 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. Theyhybridize easily, producingL. x sinoamericanum cultivars.[citation needed]
Flowers are 3–10 cm in diameter and have ninetepals — three green outersepals and six innerpetals which are yellow-green, with an orange flare at the base inL. tulipifera andL. x sinoamericanum. They start forming after around 15 years and are superficially similar to atulip in shape, hence the tree's name. Flowers ofL. tulipifera have a faintcucumber odor. Thestamens andpistils are arranged spirally around a central spike orgynaecium; the stamens fall off, and the pistils become thesamaras. Thefruit 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.[citation needed]
Liriodendron trees 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 tulip trees of height and girth not seen in other species of eastern hardwoods.[citation needed]
In the Appalachian cove forests, trees 150 to 165 ft in height are common, and trees from 166 to nearly 180 ft are also found. MoreLiriodendron over 170 ft in height have been measured by the Eastern Native Tree Society than for any other eastern species. The current tallest tulip tree on record has reached 191.9 ft, the tallest nativeangiosperm tree known in North America.[9] The tulip tree is rivaled in eastern forests only bywhite pine,loblolly pine, andeastern hemlock. Reports of tulip trees over 200 ft have been made, but none of the measurements has 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 onlyclinometers/hypsometers when measuring height.[citation needed]
Maximum circumferences for the species are between 24 and 30 ft at breast height, although a few historical specimens may have been slightly larger. TheGreat Smoky Mountains National Park has the greatest population of tulip trees 20 ft 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 cu ft (110 m3).[citation needed]
Liriodendrons have been reported as fossils from theLate Cretaceous and earlyTertiary of North America and central Asia. They are known widely as Tertiary-agefossils in Europe and well outside their present range in Asia and North America, showing a once-circumpolar northern distribution. Like many"Arcto-Tertiary" genera,Liriodendron apparently became extinct in Europe due to the east-west orientation of its mountains that blocked southward migration during the large-scaleglaciation and aridity of climate during glacial phases.[10]
The genus name should not be confused with an extinct genus known only through fossils. That isLepidodendron, which entails an important group of long-extinctpteridophytes in the phylumLycopodiophyta that are well knownPaleozoiccoal-age fossils).[citation needed]
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Liriodendron trees prefer atemperate climate, sun or part shade, and deep,fertile, well-drained and slightlyacidicsoil. Propagation is by seed orgrafting. Plants grown from seed may take more than eight years to flower. Grafted plants flower depending on the age of thescion plant.[citation needed]
The wood of the North American species (called poplar ortulipwood) is fine grained and stable. It is easy to work and commonly used for cabinet and furniture framing, i.e. internal structural members and subsurfaces forveneering. 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 around 24 lb/cu ft (0.38 g/cm3).[citation needed]
The name canoewood probably refers to the tree's use for construction ofdugout canoes by eastern Native Americans, for which its fine grain and large trunk size is eminently suited.[citation needed]
Tulip tree leaves are eaten by thecaterpillars of someLepidoptera, for example theeastern tiger swallowtail (Papilio glaucus).[citation needed]
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