Although yellow poplars, Lombardy poplars and hybrid poplars sound like they should be similar, they are not. They are not even the same species. Hybrid poplars is actually a term that applies to quite a number of hybrid Populus clones. In fact, the Lombardy poplar is actually a hybrid, although it is not usually grouped with them. Yellow poplars, Liriodendron tulipifera, are not even in the same Populus genus as other poplars. It is actually part of the same family as magnolias. They are also known as tulip trees, tulip magnolias, tulip poplars and whitewoods.
The Lombardy poplar is a hybrid of the black poplar (Populus nigra) from northern Italy. Yellow poplars are native to the eastern United States. Hybrid poplars range from all over, some being natural crosses that occurred within the United States, while others are man-made crosses.
These three trees do not have much in common besides their name. All three varieties like to be planted in full sun. They also are fast-growing and have bark that is grayish. In the fall, all three have foliage that turns yellow.
The yellow poplar is the tallest; it can grow 70 to 90 feet high. Lombardy and hybrid poplars tend to stay smaller but can still reach a height of 60 feet. Yellow poplars also have the widest spread, 40 feet, with hybrids a close second with a spread of 20 to 35 feet. Lombardy poplars are very narrow and have only a 10-foot spread.
Flowers and Fruit
The yellow poplar produces orange, yellow or green tulip-shaped flowers in the spring that turn in a cone-shaped fruit. The Lombardy poplar and poplar hybrid produce red or reddish-brown catkins. The Lombardy poplar does not produce fruit, but poplar hybrids do. They have light brown seeds surrounded by "cotton."
Lombardy and yellow poplars prefer a moist, well-draining, fertile soil. Poplar hybrids prefer a loamy soil. Lombardy poplars and some poplar hybrids are drought tolerant, but yellow poplars are not. Lombardy poplars are pH adaptable, while hybrid and yellow poplars prefer a soil with a slightly acidic pH.
Disease and Pest Resistance
Disease and pest resistance of hybrid poplars vary depending on the hybrid. For example, Assiniboine poplar (Populus x Assiniboine) and Imperial Poplar (P. x euramericana Imperial) are known for being more disease resistant than other hybrids. It goes without saying that hybrid poplars tend to have less problems with disease and pests than yellow and Lombardy poplars. Lombardy poplars are well-known for being extremely canker-prone. Meanwhile, yellow poplars can have problems with aphids, sooty mold, leaf spot, leaf scorch, cankers, verticillium wilt and scales