Tuliptree, Tulip Tree, Tulip Poplar, or Yellow Poplar

(Magnoliaceae - Magnolia Family)

Form

• large shade tree, and also a large ornamental tree
• maturing at up to 80' tall by 40' wide under urban conditons, but well over 100' tall in the wild
• upright pyramidal growth habit with a strong central leader in youth and middle age, becoming columnar then irregular, spreading, or open with old age
• rapid growth rate

Culture

• full sun to partial sun
• prefers full sun in a deep, rich, moist soil that at times can be wet, but a mature tree with a fully established root system adapts to drier soils with resulting Summer interior leaf drop
• propagated by seeds or rooted cuttings
• Magnolia Family, with several relatively minor disease and insect problems, but aphids can cause the cosmetic secondary problem of their honeydew secretion causing sooty mold buildup on the leaves
• moderately available, primarily in ball and burlap form
• young trees that have been root-pruned (i.e., transplanted in a balled and burlaped state) should be regulary watered for at least three years following transplanting
• Tuliptree is extremely sensitive to being transplanted in the Autumn (a general characteristic of fleshy-rooted and coarsely-rooted woody plants), and extra care should be taken to amend the soil, fertilize, water thoroughly, mulch adequately, and avoid Winter salt spray, to enhance survival chances during the first Winter, if transplanting cannot be delayed until Spring

Foliage

• medium green, alternate, and broadly ovate, overall with a square shape, with both a truncate base and a truncate, shallowly wedge-shaped apex, having several shallow lateral lobes and a long petiole
• the bilateral halves of the leaf blade are folded into flag-like outline at leaf emergence, then separate like a butterfly's wings at the midrib as the leaf expands
• distinctive rounded stipules occur at the base of each petiole on the young leaves, abscising during the Summer
• due to the wide, flat leaf base and long petiole, the leaf blade flutters in the slightest breeze
• often has limited defoliation of yellowing leaves in the interior of the tree by late July to early August as a response to Summer drought (and is therefore an indicator plant for drought conditions)
• one of the best trees for yellow to golden-yellow fall color

Flowers

• large, solitary, showy flowers have six yellow-green petals surrounded by three green sepals and resemble a huge tulip (hence the common name)
• interior of the flower contains a bright orange and yellow corolla, surrounding the central spire of immature aggregate fruits
• flowering in late May and throughout June
• 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
• older trees flower heavily and their lowermost branches become pendulous, allowing for visualization of the beautiful flowers up-close

Fruits

• each fruit is a green to chartreuse aggregate of samaras in the shape of an upright cone, turning light brown in the Winter and sometimes persisting into the following growing season
• upon abscission from the aggregate fruits, the winged samaras twirl downward in a spiraling fashion to the ground

Twigs

• green to red-brown, depending upon season, and noticeably lenticeled
• each terminal bud is valvate (duck-billed), with the lateral buds being much smaller
• leaf scars and the circling stipule scars are prominent on the first- and second-year stems

Trunk

• often the tallest and straightest tree in the open field or forest, ascending to great heights before finally losing its central leader and upper branches due to storms that twist the lightweight wood
• bark is distinctive in its light gray shades of youth blending into the light brown tones of maturity, with interlacing ridges that are contrasted with deep furrows on the straight trunks
• the olive to off-white-colored wood can be used as pulp for paper production, but is often used as a veneer base for furniture due to its being lightweight, relatively strong, not easily splittable, and porous for glue penetration

ID Summary

• leaves flutter in the slightest breeze
• leaves have a truncate base and a truncate to broadly wedge-shaped apex
• prominent stipules occur at each petiole base when leaves are newly emergent, and encircling stipule scars remain on first and second-season twigs
• large yellow tulip-like late Spring flowers on mature trees
• valvate Winter terminal buds
• in youth, the growth habit is strongly pyramidal, with a straight trunk and highly symmetrical lateral branching
• on mature trees growning in the open, the lower branches cascade with age and have upturned ends

USAGE

Function

• shade, specimen, ornamental, or focal point tree (should be used more often in large lawn, park, or naturalized areas, and not used in restricted urban areas as a shade tree)

Texture

• bold texture in foliage and medium texture when bare
• thick density in foliage but average density when bare

Assets

• very quick establishment and growth, especially in areas with moist, deep soils
• foliage flutters in the slightest breeze
• symmetrical and pyramidal growth habit from youth through mid-age, for a stately appearance
• abundant and showy late Spring tulip-like flowers on mature trees
• tolerant of constantly moist to occasionally wet sites

Liabilities

• central leader and upper branches become somewhat storm-prone (wind, lightning, or ice) in later years as the tree ascends to great heights and is subject to the destructive physical forces of nature
• some interior leaf abscission almost always occurs in mid- to late-Summer as a response to drought, long before normal Autumn leaf drop
• gets far too tall and large for restricted urban areas

Habitat

• zones 4 to 9
• native to the Eastern United States

SELECTIONS

Alternates

• shade trees with rapid establishment (Alnus glutinosa, Betula nigra, Fraxinus pennsylvanica, Gleditsia triacanthos, Liquidambar styraciflua, Sophora japonica, Zelkova serrata, etc.)
• shade trees with excellent fall color (Acer rubrum, Acer saccharum, Betula lenta, Fraxinus americana, Quercus rubra, Ulmus parvifolia, Zelkova serrata, etc.)
• large shade trees with large, showy flowers (Magnolia grandiflora, Sophora japonica, etc.)
• trees whose foliage flutters in the slightest breeze (Alnus glutinosa, Populus deltoides, Populus tremuloides, etc.)
• very tall, pyramidal, or symmetrically branched trees (Abies concolor, Alnus glutinosa, Liquidambar styraciflua, Picea abies, Picea pungens, Quercus palustris, Taxodium distichum, Tilia cordata, etc.)

Variants

• the species form is the primary form available, but several cultivars are rarely available that differ in either growth habit or foliage variegation

NOTES

Translation

• Liriodendron translates from the Greek as "lily tree", perhaps because the flowers also generally resemble lilies.
• tulipifera translates as "tulip-bearing", referring to the specific resemblance of the flowers to tulips.
• paleontologically speaking, Tuliptree is actually a very old tree that is recorded in fossils, being a "deciduous Magnolia".

Purpose

• Tuliptree is one of the few shade trees to have showy flowers.

Summary

• Liriodendron tulipifera is a flowering shade tree commonly found in the open forests and fields of the Eastern United States, characterized by its tall, pyramidal, straight, symmetrical, and fast-growing growth habit, by its showy tulip-like flowers on mature trees, and also being an important timber tree for the veneer and paper pulp industries.