Liriodendron tulipifera Seeds | Tulip Tree
LATIN NAME: Liriodendron tulipifera
COMMON NAME: Tulip Tree
Plant Profile
The genus Liriodendron once circled the northern hemisphere, but the Ice Ages left exactly two species alive: this one in eastern North America and its Chinese sibling, Liriodendron chinense, in the mountains of central China. The pair is the textbook case of the eastern-Asian and eastern-North-American disjunction, populations sundered for millions of years yet still so alike that botanists can hybridise them.
Botanically the flower is a primitive magnolia-family affair: a shallow green calyx, six pale greenish-yellow petals flushed orange at the base, and a spiral of stamens around a cone of carpels that will become the samara cluster. The structure is a window into early flowering-plant anatomy, one reason the genus appears so often in plant-evolution teaching material. After flowering, the spent cups set the slender seed cones that ripen through late summer.
The species makes a superlative avenue tree but demands the right street: its roots run shallow and greedy near the surface, so plant it well back from paths and drains, and expect leaf drop and honeydew over paving beneath the crown. Given that space, the reward is a tree that climbs skyward year after year and ends every season in sheet gold. In large gardens it pairs well with late-flowering perennials that take the sun before the canopy closes.
Science & Biotechnology
Chemists have pulled two headline molecules from the tulip tree. The oxoaporphine alkaloid liriodenine, first characterised from this species, has been a workhorse of alkaloid pharmacology research, and the sesquiterpene lactone lipiferolide drew attention in studies of plant compounds that deter insect feeding. On the industrial side the wood is prized precisely for what it lacks: low resin content and a pale, even colour that takes dye and pulping equally well.
Uses & Benefits
Growth is famously quick, and plantation managers value tulip poplar as one of the fastest upright hardwoods for the temperate zone. The lumber, sold as yellow poplar, is light, straight-grained and stable, which is why it dominates drawer sides, veneer cores, picture frames and painted furniture. The uniform grain even suited the pattern and core timber of early aircraft propellers.
As an ornamental it is a tree of scale: avenues, parks, campuses and estate lawns, where the autumn leaf-fall in clear gold is one of the spectacles of the temperate year. Beekeepers prize it as a major nectar source, and tulip poplar honey, dark and slightly minty, is a regional classic in the Appalachian and Ohio Valley forests. The high flowers are worked chiefly by bees and beetles feeding on the nectar pooled at the base of the petals.
Growing from Seed
The tulip tree is one of the tallest hardwoods of eastern North America, passing fifty metres in sheltered Appalachian coves, with a trunk that rises clean and columnar under a high crown. The leaves are instantly recognisable, four-lobed with a flat, notched tip that gives the species one of its folk names, saddletree. The flowers that give the tree its name are curious upright cups of green and orange, tulip-shaped and held high in the crown in early summer, where only the bees and the tallest ladders see them at eye level.
The fruits are slender cones of spirally packed winged nutlets, browning in autumn when the aggregate can be picked and crumbled to release the samaras. A period of cold, moist storage through winter evens out spring emergence. Sow about one centimetre deep in a loamy, freely draining mix, and keep the tray shaded and evenly damp until the seedlings stand.
Young tulip trees make an early push of taproot, so raise them in deep cells or beds and never let them stand root-bound. Transplant while small, when they are fifteen to thirty centimetres tall, because larger stock moves poorly. Site them in full sun with room to become enormous, water through the first two summers, and watch young foliage for aphid honeydew, which is messy above but harmless to the tree itself.
Our Take
Nothing else in the temperate garden combines such speed, height and clean timber with flowers worth the wait, and we plant it wherever there is sky to fill. Its Magnoliaceae kin are worth exploring too: the fragrant Yulan magnolia for early spring, and the wide-cross saucer magnolia for a smaller garden.
Related Reading
If Tulip Tree appeals to you, these related plants are worth a look: