The modern-day tulip tree (Liriodendron tulipifera) traces its lineage back to the Lower Cretaceous period – a time when dinosaurs roamed the Earth, say Prof David Dilcher of Indiana University and his co-author from Russia.
The tulip tree, sometimes called tulip poplar or yellow poplar, is one of the largest trees of Eastern North America, sometimes reaching more than 150 feet in height. It is native from southern New England westward to Michigan and south to Louisiana and Florida.
Prof Dilcher discovered fossil flowers and fruits resembling those of magnolias and tulip trees in 1975 in Kansas. He, along with colleagues, published information about the fossils and named the plant Archaeanthus.
But the relationship between the fossils and any living plant species remained a mystery – until now.
In a new study, Prof Dilcher with Dr Mikhail Romanov from the N. V. Tcitcin Main Botanical Garden, Russia, used advanced technologies of light, scanning electron and polarizing microscopy to develop a more detailed picture of the Archaeanthus flowers, fruits and seeds and compare them with the flowers, fruits and seeds of contemporary plants.
Their results, published in the American Journal of Botany, suggest the tulip tree line diverged from magnolias more than 100 million years ago and constitutes an independent family, Liriodendraceae, with two living species: one in the Eastern United States and the other in Eastern China.
“We discovered features of the fruits and seeds, not previously detailed, that were more similar to those of the tulip tree line of evolution than to the magnolias. Thus the beautiful tulip tree has a lineage that extends back to the age of the dinosaurs. It has a long, independent history separate from the magnolias and should be recognized as its own flowering plant family,” Prof Dilcher explained.
“While the study provides new insight into the evolution of the tulip tree line, questions remain,” Prof Dilcher said.
Scientists don’t know how widespread and various the early members of the tulip tree line may have been, for example. Fossils similar to Archaeanthus have been found in the Southeastern United States. Were there other similar plants, and where did they develop?
Further, the fact that the tulip tree family has survived and evolved for more than 100 million years is relevant to understanding how species have developed in the past and how they might fare in the future given changing climate and other factors.
Bibliographic information: Mikhail S. Romanov and David L. Dilcher. 2013. Fruit structure in Magnoliaceae s.l. and Archaeanthus and their relationships. Am. J. Bot., vol. 100, no. 8, pp. 1494-1508; doi: 10.3732/ajb.1300035