the disjunct twinleaf

May 1, 2006

in Natural history

JeffersoniaA favorite native plant in my wildflower garden is twinleaf, Jeffersonia diphylla.  The flowers are similar to that of bloodroot, Sanguinaria canadensis,  which I also have spreading all over nearby.  But you can see where twinleaf gets both its common and specific names, from the deeply cleft leaf.

The only other species of Jeffersonia, J. dubia, is found in Manchuria.  Jeffersonia is one of about 65 genera of plants with disjunct populations in eastern North America and eastern Asia, which lie at about the same latitude and have similar climates.  These taxa have representatives in these two regions, but no place else in the world.  The plants have few close relatives near where they do occur, but similar taxa are present in the fossil record in Europe and other areas along the same latitudes.

The historical genesis of these disjunct populations is a complicated mix of climate change, including glaciations, and biogeography, including continental drift, over many thousands of years, breaking up what were once continuous bands of forests across the northern hemisphere. Other examples of North American plants with sister taxa in eastern Asia include Campsis (trumpet creepers), Podophyllum (mayapples), Nyssa (tupelo and black gum trees), and Cornus (dogwoods).

I’ve had this plant for years, and it gets a little bigger, but has not spread as might be expected. I’d love to have more.  The seeds are gathered by ants, which evidently take them home, as I’ve read new plants sprout from ant mounds.  I’ve tried collecting seed myself from the large pods (another name for twinleaf is “helmet pod,” great illustration of the dried pods here), but so far I’ve not had any luck germinating them. If anybody has had luck in propagating twinleaf via seed, let me know.

Aydin May 2, 2006 at 2:23 pm

There are many plant & animal taxa with similar disjunct ranges in the eastern U.S. & eastern Asia. The slug family Philomycidae, endemic to the eastern U.S. and Korea, is one of them.

biosparite May 2, 2006 at 6:11 pm

The Thomas Jefferson Center for Historic Plants (or whatever it calls itself these days) published a newsletter called TWINLEAF at one time. You may be able to get some there; try going to the Monticello website.

biosparite May 2, 2006 at 6:20 pm

I just sent you the page from Monticello under separate cover via e-mail. You can order bare-rooted Twinleaf plants at $10.00 per plant with an order cutoff date of June 4.

John May 3, 2006 at 1:13 pm

The Aix genus has a similer split as well (wood duck / mandarin duck).

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