Liriodendron tulipifera flower,
Sumter, South Carolina
|Scientific classification |
Liriodendron chinense (Hemsl.) Sarg.
Liriodendron tulipifera L.
Liriodendron is a genus in the magnolia family (Magnoliaceae) consisting of two species of large deciduous trees, one native to eastern North America, the other to China. The standard English name is variously given in three different formats, as two words Tulip tree (the commonest form in popular usage), hyphenated as Tulip-tree, or compound as Tuliptree (these formats more often used in botanical texts).
Leaf on mature tree, Sumter, South Carolina
These trees are easily recognized by their leaves, which are very unusual, having four lobes in most cases and a cross-cut notched or straight apex; size varies from 8-17 cm long and 6-12 cm broad in both species; the petiole is 4-10 cm long. Leaves on young trees tend to be more deeply-lobed than those on mature trees (see photos, left).
The flowers are 4-8 cm in diameter and have nine tepals, three short outer sepal-like, and six inner petal-like, all yellow-green in colour. They are superficially similar to a tulip in shape, hence the tree's name. The stamens and pistils are arranged spirally around the spike; the stamens fall off, and the pistils become the samaras. The fruit is a cone-like aggregate of samaras, 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.
The best known is the American Tulip Tree, L. tulipifera, also called the Tuliptree Magnolia, or sometimes confusingly, "tulip poplar" or "yellow poplar" (though it is not a poplar, family Salicaceae). The blossoms of this species yield large quantities of nectar and the species is a major honey plant in eastern USA, yielding a dark reddish, fairly strong flavoured honey. The flowers have an orange band on the tepals. This species can grow to more than 50 m in virgin cove forests of the Appalachian Mountains, often with no limbs until it reaches 25-30 m in height, making it a very valuable timber tree. It is fast-growing, without the common problems of weak wood strength and short lifespan often seen in fast-growing species. It has been introduced to many temperate parts of the world, at least as far north as Oslo, Norway. In Canada, it is native to that part of Ontario south of a line from Hamilton to Sarnia, with many specimens in Rondeau Provincial Park, but most cultivation is seen in British Columbia. There, it has been planted on the Queen Charlotte Islands and is common in southwestern cities such as Burnaby, New Westminster, Port Alberni, Vancouver and Victoria. In the Southern Hemisphere, it is cultivated in parts of Argentina, Australia, Chile, New Zealand and South Africa.
Less well-known is the Chinese Tulip Tree, L. chinense. This native of central and southern China is very similar to the American species, differing in the often slightly more deeply-lobed leaves, and in the shorter inner tepals in the flower, which lacks the orange pigment of L. tulipifera. The maximum size of the Chinese tulip tree is not known due to a long history of overcutting in its native forests; in cultivation it grows as fast as the American tulip tree, but has not been cultivated long enough to determine its potential mature size, with the largest being about 30 m tall so far. It is not as hardy as the American species, but has been successfully introduced to England, Ireland, Belgium and the Netherlands. In North America, it grows as far north as Boston, Massachusetts in the east and Vancouver, Canada in the west.
Mature Liriodendron tulipifera
Tulip trees make magnificently-shaped specimen trees, but are very large, growing to about 35 meters in good soil. Like other members of the Magnolia family, they have fleshy roots that are easily broken if handled roughly. Transplanting should be done in early spring, before leaf-out. Most tulip trees are intolerant of prolonged inundation; however, a coastal plain swamp ecotype in the United States is relatively flood-tolerant. This ecotype is recognized by its blunt-lobed leaves, which may be a reddish blush color. Parts of east-central Florida near Orlando are home to a semi-evergreen ecotype that flowers much earlier (sometimes in February) than other varieties, which usually bloom in mid or late spring.
The soft, fine-grained wood is highly prized for cabinet making and many other uses. It is clearly the wood of choice for use in organ-building, due to its ability to take a fine, smooth, precisely-cut finish and so to effectively seal against pipes and valves. It is also commonly used for siding clapboards. Its wood is comparable in texture, strength, and softness to white pine, and the two can be used interchangeably.
- Hunt, D. (ed). 1998. Magnolias and their allies. International Dendrology Society & Magnolia Society. (ISBN 0-9517234-8-0)
- Moriaty, William. The Tulip Tree in Central Florida (http://www.floridata.com/tracks/trees/TulipPoplarCentFla.htm)
- Chinese Tulip Tree photos (http://www.asahi-net.or.jp/~db3t-kjmt/kigi/sinayuri.htm)